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Harrison's Part

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Discussions and Knowledge Gaps

5

Is tropical endomyocardial fibrosis actually caused by eosinophil-mediated endocardial injury, or has that mechanism been imported wholesale from hypereosinophilic syndrome on the strength of a shared end-stage lesion?

KNOWLEDGE GAP OPEN eosinophil_hypothesis_untestable_in_endemic_setting

Attached to

pathophysiology#Sustained eosinophilia and Th2-skewed immune activation pathophysiology#Eosinophil degranulation and endocardial injury

The eosinophil model is coherent and is directly evidenced in hypereosinophilic syndrome, where the acute infiltrative stage, the thrombotic stage, and the fibrotic stage are all observed prospectively in the same patients. In tropical endomyocardial fibrosis, none of that is observed. Patients present at the fibrotic stage, eosinophilia is usually absent by then, and biopsy at that point is uninformative in a specific and vicious way, because degranulation and replacement by fibrosis erase the evidence of the very process being looked for. The inference therefore runs backwards from a shared end-stage appearance, which is exactly the reasoning pattern that would also be satisfied if two different upstream processes converged on one scar. The alternative worth taking seriously is that the endemic disease is driven by something else entirely, with the eosinophilic endocarditis of hypereosinophilic syndrome being a separate route to the same architecture. Population screening now makes the decisive study possible for the first time, because it identifies affected people before the fibrotic stage.

Proposed experiments

Longitudinal follow-up of screen-detected early endomyocardial fibrosis with serial eosinophil and cardiac biomarker measurement

exp_emf_prospective_early_stage_cohort

Enrol screen-detected asymptomatic and mild cases from an endemic population, and follow them with serial eosinophil counts, troponin, cardiac magnetic resonance tissue characterisation, and echocardiographic severity scoring, comparing those who progress against those who do not.

Decision criterion

Eosinophilia or a troponin and magnetic resonance signature of active eosinophilic inflammation preceding progression would establish the eosinophil route in the endemic disease; progression without any such signal would show that the mechanism inferred from hypereosinophilic syndrome does not transfer.

Show evidence (2 references)

PMID:34172539 SUPPORT Human Clinical

"may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"

Documents precisely why the mechanism cannot be confirmed at the stage at which the endemic disease is diagnosed.

PMID:32420110 SUPPORT Human Clinical

"efforts to understand its mechanisms and natural history have been hampered by the incapacity to detect the early stages of the disease in endemic areas"

States the structural reason the mechanism is unresolved, and by implication what would resolve it.

Why is endomyocardial fibrosis confined to specific equatorial regions, when the exposures proposed to cause it are not?

KNOWLEDGE GAP OPEN geographic_distribution_unexplained

Attached to

pathophysiology#Chronic antigenic or toxic stimulus in a susceptible host

This is the constraint every etiologic hypothesis has failed. Filariasis and schistosomiasis are widespread far beyond the endemic zone; cassava is eaten across the tropics; malaria's distribution does not match the disease's. A systematic review across six decades concluded that no proposed account explains the geography. Three structurally different explanations remain open. The cause may be a genuinely localised exposure not yet identified, such as a soil geochemical factor, in which case the geography is the signal rather than the puzzle. It may require a specific conjunction of exposures that happens to co-occur only in those regions, in which case single-factor studies were always going to fail. Or the apparent geography may be substantially an artefact of where anyone has looked, which population screening in non-endemic tropical regions could test directly and cheaply.

Proposed experiments

Standardised echocardiographic prevalence survey across matched endemic and non-endemic tropical regions

exp_emf_geographic_screening_survey

Apply the same standardised echocardiographic criteria and severity score used in the Mozambique population study to random population samples in tropical regions with comparable helminth burden, diet, and poverty but no reported endomyocardial fibrosis, alongside a contemporaneous endemic-region sample as a positive control.

Decision criterion

Comparable prevalence in supposedly non-endemic regions would show the geography is largely an ascertainment artefact and would redirect etiologic search away from localised exposures; a genuinely sharp geographic boundary under identical ascertainment would make a localised environmental factor the leading hypothesis and would define where to look for it.

Show evidence (1 reference)

PMID:18301727 SUPPORT Human Clinical

"Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution."

The systematic review's conclusion, which is the premise of this gap.

Do the mild, asymptomatic cases found by population echocardiographic screening progress to clinical endomyocardial fibrosis, or are they a largely stable finding?

OPEN QUESTION OPEN screen_detected_disease_natural_history

Attached to

pathophysiology#Dense endocardial fibrous scar pathophysiology#Restrictive diastolic physiology

Screening a rural Mozambican population found echocardiographic disease in nearly a fifth of people, but only 22.7 percent of those were symptomatic and most had only mild-to-moderate abnormalities. Two readings have opposite consequences. If most screen-detected cases progress, then the clinical disease is the visible fraction of a very large iceberg, screening would identify a huge population for early intervention, and the prevalence figure is a public-health emergency. If most are stable, then the screening criteria are detecting a common structural variant or a self-limited healed lesion, and treating the prevalence as a burden estimate overstates it substantially. No longitudinal follow-up of a screen-detected cohort has been published, so the question is open on the evidence rather than merely contested.

Proposed experiments

Ten-year longitudinal follow-up of an echocardiographically screen-detected endomyocardial fibrosis cohort

exp_emf_screen_detected_longitudinal_followup

Re-examine the screen-detected cohort at fixed intervals with the same standardised criteria and severity score, recording progression in severity grade, onset of symptoms, incident complications, and mortality, against screen-negative controls from the same sampling frame.

Decision criterion

Substantial progression in severity grade or symptom onset in a majority of screen-detected mild cases would establish them as early disease and justify screening programmes; stability across a decade would require the screening criteria to be recalibrated and the prevalence figure reinterpreted.

Show evidence (2 references)

PMID:18596273 SUPPORT Human Clinical

"Most affected subjects had mild-to-moderate structural and functional echocardiographic abnormalities. Only 48 persons with endomyocardial fibrosis (22.7%) were symptomatic."

The observation that creates the question, with the numbers that make its resolution consequential.

PMID:18596273 SUPPORT Human Clinical

"By using echocardiography, we were able to detect early, asymptomatic stages of the disease."

The authors' own interpretation, that these are early stages, which is the reading the proposed follow-up would test.

Do circulating anti-myocardial antibodies sustain injury in endomyocardial fibrosis, or merely mark injury that has already occurred?

OPEN QUESTION OPEN autoimmunity_cause_or_consequence

Attached to

pathophysiology#Anti-myocardial autoantibody response

Anti-myocardial IgG is present in about half of patients and a tenth of controls, and its intensity correlates with disease activity. Correlation with activity is compatible with both readings, since an antibody that drives injury and an antibody that reports injury would both track it. The authors of the only study explicitly declined to resolve it. The stakes are concrete rather than academic: only the causal reading would justify trialling immunosuppression in a disease that currently has no medical therapy at all, and giving immunosuppression on the strength of a marker would expose a malnourished, often parasitised population to real harm. That trial has in fact been attempted once. A pilot randomised trial of prednisolone in 35 Ugandan patients found the drug safe but failed to show a reduction in ascites reaccumulation, with a relative risk of 0.70 and a confidence interval crossing one. It targeted the ascites rather than the autoantibody arm, and with 16 patients on active drug and six lost to follow-up it cannot exclude a modest effect, so it does not settle this question. It does mean the question is no longer purely hypothetical, and that any future immunosuppression proposal has to say what it would do differently.

Proposed experiments

Serial autoantibody measurement in a screen-detected cohort followed to progression

exp_emf_autoantibody_temporal_sequence

Measure anti-myocardial IgG serially in screen-detected early cases, and determine whether antibody appearance and titre rise precede or follow echocardiographic progression in individual patients.

Decision criterion

Antibody appearance preceding progression within individuals would support a causal or perpetuating role and would justify a pilot immunosuppression trial; antibody rise following progression would establish it as a marker and rule out that trial.

Show evidence (3 references)

PMID:20422043 SUPPORT Human Clinical

"These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF, therefore improving its management by identifying patients who may benefit from immunosuppressive therapy."

States the activity correlation and the therapeutic hope that rests on the causal reading.

PMID:20422043 SUPPORT Human Clinical

"it is unclear whether the primary target of injury is the endocardial endothelium, the subendocardial fibroblast, the coronary microcirculation or the myocyte"

The authors' framing of the unresolved question about what is being injured, which this discussion extends to what is doing the injuring.

PMID:26666319 REFUTE Human Clinical

"There was no statistically significant difference in the overall risk of developing grade 3 ascites over 8 weeks."

The one attempt at immunosuppression in this disease, and it was negative on its primary endpoint, which constrains the therapeutic argument this discussion turns on.

How much of what is unknown about endomyocardial fibrosis reflects genuine biological difficulty rather than the absence of research capacity where the disease occurs?

CURATION TODO OPEN research_neglect_as_a_disease_feature

Attached to

pathophysiology#Chronic antigenic or toxic stimulus in a susceptible host

This entry has no transcriptomic, proteomic, metabolomic, or single-cell data to cite. It has exactly one molecular-profiling study of any kind, a plasma cytokine panel in 27 patients, and one randomised trial, a 35-patient pilot of prednisolone that was negative. Its only genetic association has never been replicated, its only animal model dates from 1996, and the only cell system in use is explicitly described by its own authors as not a disease model. That is the entire modern molecular literature for a disease affecting nearly a fifth of a screened population. Publication volume has fallen since the 1980s. These are not properties of the biology; they are properties of where the biology happens. The curation consequence is that absence of evidence in this entry should not be read as evidence of absence anywhere it appears, and that flagging a gap here is frequently a statement about research funding rather than about a hard scientific problem. This is recorded as a standing caveat over the whole entry rather than as a question with an experiment attached.

Show evidence (2 references)

PMID:18301727 SUPPORT Human Clinical

"The volume of publications on endomyocardial fibrosis has declined since the 1980s."

Quantifies the decline in research attention to a disease of this prevalence.

PMID:32420110 SUPPORT Human Clinical

"can be used to expose global disparities in cardiovascular research"

The authors' own framing of the disease as an index of research inequity.

⚙

Pathophysiology

14

Chronic antigenic or toxic stimulus in a susceptible host

The initiating exposure is not established. Chronic helminth infection, malaria, cassava-based diets with protein deprivation, and geochemical exposures such as cerium in monazite-rich soils have all been proposed, and none accounts for the disease's distribution. The strongest structural observation is negative: hypotheses that explain why the disease occurs where it does fail to explain why it does not occur in other regions with the same parasite burden or the same diet. What is well supported is that exposure alone is insufficient, since only a minority of people living in identical conditions develop the disease.

Experimental models

Cassava-fed Cercopithecus aethiops with protein deprivation OTHER The model instantiates the proposed dietary toxic exposure directly.

Plantain and serotonin dietary models OTHER The models tested a dietary serotonin exposure as the proposed toxic stimulus, and failed to reproduce the disease.

Downstream

Sustained eosinophilia and Th2-skewed immune activation A chronic antigenic stimulus in a susceptible host is proposed to drive persistent eosinophilia, which is the first step of the mechanistic model.

Show evidence (2 references)

PMID:18301727 SUPPORT Human Clinical

"Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution."

The systematic review's central negative conclusion, which is why this node is deliberately unspecific.

PMID:41399600 SUPPORT Human Clinical

"its etiology remains poorly understood, with proposed contributors including malnutrition, parasitic infections, hypereosinophilia, and genetic predisposition"

Enumerates the candidate exposures without privileging any, matching the state of the evidence.

Sustained eosinophilia and Th2-skewed immune activation

Persistent eosinophilia is the pivot of the accepted model. In hypereosinophilic syndrome, where the eosinophil count is by definition high and the cardiac disease is followed prospectively, eosinophil-mediated endomyocardial damage is directly established. In tropical endomyocardial fibrosis, eosinophilia is variably present and typically absent by the time the fibrotic stage is diagnosed, so the inference runs backwards from a shared end-stage lesion. That asymmetry is real and is curated as such rather than smoothed over.

Eosinophil CL:0000771

inflammatory response GO:0006954 ↑ INCREASED

Downstream

Eosinophil degranulation and endocardial injury Eosinophils infiltrate the subendocardium and release granule proteins that damage endothelium and subendocardial myocytes.

Show evidence (5 references)

PMID:34172539 SUPPORT Human Clinical

"Eosinophil-mediated endomyocardial damage is a well-known complication in patients with hypereosinophilic syndromes (HES)."

The direct evidence for eosinophil-mediated endomyocardial damage comes from hypereosinophilic syndrome, which is the model the tropical disease is read through.

PMID:31414216 SUPPORT INDIRECT Human Clinical

"Although its pathogenesis and etiology are not fully understood, its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome."

States the pathologic resemblance that licenses the inference from hypereosinophilic syndrome to tropical endomyocardial fibrosis. Graded INDIRECT because resemblance is not identity.

PMID:25303100 SUPPORT Human Clinical

"We found that TNF-α, IL-6, IL-4, and IL-10 were each detected in at least 74% of tested sera, and plasma levels of IL-10, IL-4, and TNF-α were significantly higher than those of controls."

Direct measurement of the Th2 cytokines IL-4 and IL-10 in 27 tropical endomyocardial fibrosis patients against healthy controls, which is what supports the Th2 half of this node's claim.

+ 2 more references

Eosinophil degranulation and endocardial injury

Degranulating eosinophils release cationic granule proteins into the subendocardium, injuring endocardial endothelium and the subendocardial layer of myocytes. This is Davies stage one, the acute necrotic phase, lasting some months. It is the stage almost never observed in tropical endomyocardial fibrosis, because patients in endemic areas do not present until they are in heart failure, and it is the single largest gap in the evidence for this disease.

Eosinophil CL:0000771 Endocardial endothelial cell CL:0002350

eosinophil degranulation GO:0043308 ↑ INCREASED

Endocardium UBERON:0002165

Downstream

Mural thrombus formation on the damaged endocardium The denuded, injured endocardial surface becomes thrombogenic, and mural thrombus forms over it during the second stage.

Show evidence (3 references)

PMID:41399600 SUPPORT Human Clinical

"Hypereosinophilia likely contributes to early myocardial necrosis through eosinophil granule proteins (major basic protein, eosinophil peroxidase), initiating an inflammatory-fibrotic cascade"

Names the specific granule proteins and the injury they cause, in a source about endomyocardial fibrosis itself rather than about hypereosinophilic syndrome.

PMID:38540269 SUPPORT Human Clinical

"ranging from mild asymptomatic disease to multifocal widespread infiltrates associated with myocardial necrosis, thrombotic complications, and endomyocardial fibrosis"

Links eosinophilic infiltration to myocardial necrosis, thrombosis, and endomyocardial fibrosis as a single severity spectrum.

PMID:34172539 SUPPORT INDIRECT Human Clinical

"may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"

Documents that eosinophil degranulation itself erases the diagnostic evidence of eosinophilic infiltration, which is exactly why the acute stage is under-observed. Graded INDIRECT because the statement is about biopsy yield rather than the mechanism directly.

Mural thrombus formation on the damaged endocardium

Davies stage two, beginning around ten months and running over years. Thrombus deposits on the injured endocardial surface, preferentially at the ventricular apex and beneath the posterior mitral leaflet, and is then organised rather than lysed. This is the step that converts an inflammatory injury into a structural one, and it is also the source of the systemic and pulmonary thromboembolism that complicates the disease independently.

blood coagulation GO:0007596 ↑ INCREASED

Endocardium UBERON:0002165

Downstream

Fibroblast activation and excessive collagen deposition Organisation of the mural thrombus recruits and activates fibroblasts, which lay down collagen in the subendocardial layer.

Systemic and pulmonary thromboembolism Fragments of intracardiac thrombus embolise.

Show evidence (1 reference)

PMID:34172539 SUPPORT Human Clinical

"As disease progresses, patients typically develop intracardiac mural thrombi"

Places mural thrombus formation as the intermediate stage of the eosinophilic endocardial disease sequence.

Anti-myocardial autoantibody response

Circulating IgG against myocardial proteins is present in about half of patients and in a tenth of controls, and its intensity tracks disease activity. It is curated as a parallel amplifying arm rather than as a step in the main chain, because the direction of causation is not established: antibodies could sustain injury after the eosinophilic stimulus has gone, or could simply mark exposure of intracellular myocardial antigens by injury that has already occurred. The distinction matters clinically, since only the first reading would justify immunosuppression.

Downstream

Fibroblast activation and excessive collagen deposition Continuing autoimmune myocardial injury is proposed to perpetuate the fibrogenic stimulus after the initiating eosinophilia has resolved.

Show evidence (2 references)

PMID:20422043 SUPPORT Human Clinical

"IgG reactivity against myocardial proteins was stronger and more frequent in patients with EMF when compared to controls (30/56; 53.6% vs. 1/10; 10%, respectively)."

Quantifies the autoantibody finding against healthy controls in 56 patients.

PMID:20422043 SUPPORT Human Clinical

"Further research is needed to clarify the role of autoimmunity in the pathogenesis of EMF."

The authors' own statement that the causal role is unresolved, which is why this node is curated as a parallel arm.

Fibroblast activation and excessive collagen deposition

Subendocardial fibroblasts are activated and deposit collagen and other matrix, the generic fibrogenic step this disease shares with organ fibrosis elsewhere. What is unusual is the trigger, an intraluminal eosinophil-driven injury with an organising thrombus rather than a parenchymal insult, and the site, a thin subendothelial layer rather than the interstitium of the organ.

Cardiac fibroblast CL:0000057

fibroblast activation GO:0072537 ↑ INCREASED collagen fibril organization GO:0030199 ↑ INCREASED

Experimental models

Fibroblast and cardiomyocyte coculture CO CULTURE The coculture models the fibroblast-cardiomyocyte interaction of the fibrogenic step only, downstream of the injury it cannot represent.

Downstream

Dense endocardial fibrous scar Sustained matrix deposition produces the dense acellular fibrocollagenous endocardial thickening that defines the disease.

Show evidence (3 references)

PMID:41399600 SUPPORT Human Clinical

"A key feature is fibroblast overactivation leading to excessive extracellular matrix deposition, primarily fibrillar collagen, which replaces normal myocardium and results in myocardial stiffness and electromechanical uncoupling."

The direct statement of this node, naming the cell, the matrix product, and the mechanical consequence.

PMID:41399600 SUPPORT Human Clinical

"Persistent activation of these pathways amplifies pro-fibrotic signaling (e.g., SMAD2/3 and YAP/TAZ), leading to chronic endocardial scarring"

Names the intracellular pro-fibrotic signalling that sustains the activated state.

PMID:32420110 SUPPORT Human Clinical

"an inflammatory process that leads to endomyocardial damage and scar formation"

States the inflammation-to-scar transition that this node represents.

Dense endocardial fibrous scar

Davies stage three and the irreversible end-state. The endocardium thickens to millimetres of dense, largely acellular fibrocollagenous tissue, measured at a mean of three millimetres in an operative series, with a lymphocyte-predominant infiltrate and subendocardial neovascularisation. The myocardium beneath is comparatively spared, which is why systolic function is preserved and why surgical decortication is anatomically feasible at all.

extracellular matrix organization GO:0030198 ↑ INCREASED

Endocardium UBERON:0002165

Experimental models

Cassava-fed Cercopithecus aethiops with protein deprivation OTHER The model reproduces the defining endocardial lesion, including its apical and papillary distribution.

Downstream

Apical and inflow-tract cavity obliteration Scar fills the trabecular recesses of the apex and inflow tract, reducing cavity volume.

Papillary muscle and chordal tethering Scar extends onto and around the subvalvular apparatus, fixing the papillary muscles and chordae to the ventricular wall.

Show evidence (2 references)

PMID:32420101 SUPPORT Human Clinical

"The mean endocardial thickness was 3,000 (±1519) µm."

Direct operative measurement of the scar thickness in 55 patients.

PMID:32420101 SUPPORT Human Clinical

"The echocardiographic changes corresponded well to the findings on surgery and histopathology."

Confirms that the echocardiographically defined lesion is the same lesion seen at surgery and on histology.

Apical and inflow-tract cavity obliteration

Fibrous obliteration of the apex and inflow tract removes the part of the ventricle that would otherwise accommodate diastolic filling. The apex takes on the characteristic rounded, retracted appearance on echocardiography that gives the diagnosis.

Left ventricle UBERON:0002084 Right ventricle UBERON:0002080

Downstream

Restrictive diastolic physiology Loss of compliant cavity volume raises filling pressures for any given volume.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Characterized by fibrotic thickening of the ventricular endocardium, EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure."

The full downstream sequence from the fibrous lesion to heart failure.

Papillary muscle and chordal tethering

The subvalvular apparatus is drawn into and immobilised by the scar, so the leaflets cannot coapt. The mitral regurgitation of this disease is therefore mechanical and subvalvular in origin, not a leaflet disease, which is why valve repair addresses the tethering rather than the leaflets and why decortication is done at the same operation.

Papillary muscle of heart UBERON:0002494

Downstream

Atrioventricular valve regurgitation Tethered chordae prevent leaflet coaptation, producing mitral or tricuspid regurgitation.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"

Names atrioventricular valve dysfunction as a defining consequence alongside the restrictive physiology.

Atrioventricular valve regurgitation

Mitral, tricuspid, or both, depending on which ventricle is involved, and typically severe by the time of presentation. It compounds the restrictive physiology by loading atria that are already facing high ventricular filling pressures.

Mitral valve UBERON:0002135 Tricuspid valve UBERON:0002134

Downstream

Atrial dilatation and atrial fibrillation Regurgitant volume dilates the atria, creating the substrate for atrial fibrillation.

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"had severe atrioventricular valve regurgitation with valves considered suitable for both replacements"

Operative series documenting the severity of the regurgitation.

Restrictive diastolic physiology

Ventricles that cannot fill, with preserved contraction of what myocardium remains. This is the haemodynamic signature of the disease and the reason it sits in the restrictive rather than the dilated or hypertrophic category, and it explains why ejection fraction is a useless measure of severity here.

Downstream

Congestive heart failure High filling pressures transmit backwards, producing systemic venous congestion in right-sided disease and pulmonary congestion in left-sided disease.

Show evidence (1 reference)

PMID:18596273 SUPPORT Human Clinical

"Endomyocardial fibrosis is the most common restrictive cardiomyopathy worldwide."

Places the disease in the restrictive category, and quantifies its global significance within it.

Atrial dilatation and atrial fibrillation

Massive biatrial dilatation is characteristic, driven by both the restrictive ventricles and the valve regurgitation, and brings atrial fibrillation with its own thromboembolic risk on top of the intracardiac mural thrombus already present.

Downstream

Systemic and pulmonary thromboembolism Atrial fibrillation in dilated atria adds a second source of intracardiac thrombus.

Show evidence (1 reference)

PMID:32420110 SUPPORT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

Documents arrhythmia as an established complication at the time of typical late diagnosis.

Systemic and pulmonary thromboembolism

Embolisation from ventricular mural thrombus or from fibrillating dilated atria, and one of the reasons anticoagulation features in palliative management of a disease with no disease-modifying drug.

Show evidence (1 reference)

PMID:32420110 SUPPORT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

Names thromboembolism among the complications typically present at diagnosis.

Congestive heart failure

The presenting syndrome in nearly all diagnosed cases, and typically advanced. In an operative series all but one of 55 children were in New York Heart Association class III or IV at the time of surgery, which is a statement about access to care as much as about the disease.

Show evidence (2 references)

PMID:32420101 SUPPORT Human Clinical

"All but one patient was in NYHA functional class III or IV at the time of surgery."

Quantifies how advanced the heart failure is at the point of intervention.

PMID:18596273 SUPPORT Human Clinical

"It has no specific treatment and carries a poor prognosis, since most patients present with advanced heart failure."

States the presentation stage and its prognostic consequence.

✶

Histopathology

4

Dense endocardial fibrous thickening with apical and valvular extension

The defining pathological appearance: fibrous thickening running from the ventricular apices onto the posterior mitral or tricuspid leaflets, characteristically sparing the outflow tracts. That sparing is diagnostically useful, because it distinguishes the distribution from diseases that involve the whole ventricle.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Pathologically, EMF is characterized by fibrotic thickening of the endocardium extending from the apices to the posterior mitral or tricuspid leaflets, typically sparing the outflow tracts."

The defining pathological distribution, including the outflow-tract sparing that discriminates it.

Mural thrombus, dystrophic calcification, and subendocardial neovascularisation

The accompanying features of the established lesion. Subendocardial neovascularisation is the least expected of these in what is otherwise an acellular scar, and mural thrombus is the histological trace of the intermediate stage of the disease.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Common features include mural thrombi, dystrophic calcification, papillary muscle and chordal fibrosis, and subendocardial neovascularization."

Enumerates the associated findings, including the chordal fibrosis that produces the valve regurgitation.

Stage-dependent microscopic appearance

Microscopy differs by stage rather than by side. Acute lesions show eosinophilic infiltration and necrosis; chronic lesions show dense collagen, elastic fibre fragmentation, and endocardial thickening. This is the histological form of the entry's central evidential problem, since the eosinophilic appearance is only visible in a stage that is almost never biopsied in endemic settings.

Show evidence (2 references)

PMID:41399600 SUPPORT Human Clinical

"acute lesions show eosinophilic infiltration and necrosis, while chronic lesions exhibit dense collagen, elastic fiber fragmentation, and endocardial thickening"

The stage-dependent microscopic findings that underpin the Davies staging used in this entry's progression section.

PMID:41399600 SUPPORT Human Clinical

"Left- and right-sided lesions demonstrate similar histology but differ in distribution."

Establishes that laterality changes the distribution and not the tissue lesion, which is why this entry curates one histological process across both ventricles.

Endocardial thickness at surgery

Measured at a mean of three millimetres in an operative series of 55 children, with a maximum above five and a half millimetres. The scale is what makes surgical decortication feasible: this is a peel that can be found and lifted, not a diffuse infiltration.

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"The mean endocardial thickness was 3,000 (±1519) µm."

Direct operative measurement quantifying the lesion.

⬡

Pathograph

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●

Phenotypes

15

Blood 2

Thromboembolism OCCASIONAL HP:0001907

Show evidence (2 references)

PMID:41399600 SUPPORT Human Clinical

"Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."

Gives the 15 to 20 percent rate supporting the OCCASIONAL band, which FrequencyEnum defines as 5 to 29 percent, with the source's own caveat that the estimate rests on limited regional data.

PMID:32420110 SUPPORT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

Directly names thromboembolism as an established complication.

Increased total eosinophil count FREQUENT HP:0001880

Temporal: TRANSIENT

Show evidence (2 references)

PMID:41399600 SUPPORT Human Clinical

"Limited contemporary data report variable eosinophil elevations (30%-50%) without consistent correlation to disease activity"

Gives the 30 to 50 percent rate supporting the FREQUENT band, and states the absence of correlation with activity that keeps eosinophilia from being usable as a disease marker.

PMID:31414216 SUPPORT INDIRECT Human Clinical

"its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome"

Establishes the eosinophilic relationship that motivates measuring the count. Graded INDIRECT because the abstract does not state the frequency of eosinophilia in tropical endomyocardial fibrosis itself.

Cardiovascular 4

Congestive heart failure VERY_FREQUENT HP:0001635

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"All but one patient was in NYHA functional class III or IV at the time of surgery."

Quantifies both the presence and the severity of heart failure at presentation.

Atrial fibrillation FREQUENT HP:0005110

Show evidence (2 references)

PMID:41399600 SUPPORT Human Clinical

"Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."

Gives the 30 to 40 percent rate supporting the FREQUENT band, with the source's caveat that the estimate rests on limited regional data.

PMID:32420110 SUPPORT INDIRECT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

Names arrhythmia among established complications. Graded INDIRECT because the specific rhythm is not stated.

Sudden cardiac death OCCASIONAL HP:0001645

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."

Gives the rate supporting the OCCASIONAL band, with the source's own caveat about the strength of the estimate.

Hepatosplenomegaly HP:0001433

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"RV EMF often presents with a loud tricuspid regurgitant murmur, prominent systolic jugular pulsation, and hepatosplenomegaly."

Names hepatosplenomegaly among the right-sided findings.

Digestive 2

Ascites FREQUENT HP:0001541

Show evidence (1 reference)

PMID:41399600 SUPPORT INDIRECT Human Clinical

"EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"

Establishes the congestive syndrome that produces ascites in right-sided disease. Graded INDIRECT because ascites is not named in the abstract.

Hepatomegaly HP:0002240

Show evidence (1 reference)

PMID:41399600 SUPPORT INDIRECT Human Clinical

"EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"

Establishes the congestive physiology behind hepatomegaly. Graded INDIRECT because the finding is not named in the abstract.

Respiratory 2

Dyspnea FREQUENT HP:0002094

Show evidence (1 reference)

PMID:41399600 SUPPORT INDIRECT Human Clinical

"EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"

Establishes the heart failure syndrome of which dyspnoea is the cardinal symptom. Graded INDIRECT because dyspnoea is not itemised separately.

Orthopnea HP:0012764

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"LV EMF typically manifests as exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and an apical pansystolic murmur of mitral regurgitation"

Names orthopnoea explicitly among the left-sided manifestations.

Other 5

Endocardial fibrosis OBLIGATE HP:0006685

Course: PROGRESSIVE

Show evidence (1 reference)

PMID:31414216 SUPPORT Human Clinical

"It is characterized by fibrotic thickening of the endocardium and myocardium of one or both ventricles."

The obligate defining feature.

Restrictive cardiomyopathy OBLIGATE HP:0001723

Show evidence (1 reference)

PMID:18596273 SUPPORT Human Clinical

"Endomyocardial fibrosis is the most common restrictive cardiomyopathy worldwide."

Establishes the phenotype and the disease's standing within that category.

Mitral regurgitation FREQUENT HP:0001653

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"All but one female patient with mild ventricular lesions and no valvular involvement had severe atrioventricular valve regurgitation"

Operative series showing near-universal severe atrioventricular regurgitation in patients with more than mild ventricular disease.

Tricuspid regurgitation FREQUENT HP:0005180

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"had severe atrioventricular valve regurgitation with valves considered suitable for both replacements"

Operative documentation of severe atrioventricular regurgitation requiring intervention.

Abnormal cardiac atrium morphology HP:0005120

Show evidence (1 reference)

PMID:32420101 SUPPORT INDIRECT Human Clinical

"We designed the study aimed at assessing the cardio-structural abnormalities and coronary vascular changes faced with EMF patients using echocardiography"

Establishes echocardiographic structural assessment as the method by which the atrial abnormality is characterised. Graded INDIRECT because atrial dilatation is not itemised in the abstract.

🧬

Genetic Associations

2

HLA-B

Gene: HLA-B hgnc:4932 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:25780800 SUPPORT Human Clinical

"with EMF patients being more likely than controls to have the HLA-B*58 allele in Mozambique (p-0.03)"

The reported association with its p value, in the study that is the sole formal genetic investigation of this disease.

HLA-A

Gene: HLA-A hgnc:4931 relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE

Show evidence (1 reference)

PMID:25780800 SUPPORT Human Clinical

"the HLA-A*02:02 in Uganda (p = 0.005)"

The second reported association, in the Ugandan arm of the same two-centre study.

💊

Medical Actions

6

Endocardial decortication with atrioventricular valve repair or replacement

Action: cardiac surgery Ontology label: Cardiac Surgery NCIT:C157806

The only intervention that changes the course of established disease. The fibrous endocardial peel is stripped from the ventricle to restore cavity volume and compliance, and the tethered atrioventricular valve is repaired or replaced at the same operation. Operative risk is high and the procedure is available to almost none of the people who need it, which is the defining inequity of this disease rather than a technical limitation.

Mechanism Target:

BYPASSES Dense endocardial fibrous scar — Surgical removal of the fibrous peel physically relieves the restriction the scar imposes, without addressing the process that produced it.

Show evidence (1 reference)

PMID:32420110 SUPPORT Human Clinical

"Open-heart surgery to detach the endocardial fibrous tissue and repair the atrioventricular valve, remains the last resource to prolong patients' survival."

Describes both components of the operation and its status as the only survival-prolonging option.

Show evidence (2 references)

PMID:31414216 SUPPORT Human Clinical

"Surgery in the correct setting can increase survival and especially in patients with advanced heart failure."

States the survival benefit and its conditionality on setting.

PMID:41399600 SUPPORT Human Clinical

"Surgical intervention-particularly endocardial decortication and valve repair-remains the definitive treatment for advanced cases, though it carries high operative risk"

Names the specific operation and states its risk honestly.

Atrioventricular valve replacement

Action: valve replacement Ontology label: Valve Replacement NCIT:C168093

Where the subvalvular tethering is too extensive for repair, the valve is replaced. In an operative series of 55 children, 45 were replaced and nine repaired, and the replaced patients were older, which suggests the window for repair closes as the scar advances.

Mechanism Target:

BYPASSES Atrioventricular valve regurgitation — Prosthetic replacement restores valve competence where the tethered native apparatus cannot be made to coapt.

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"45 patients mean age 6.0 (±3.1) and repair nine patients mean age 3.8 (±2.9)"

Gives the split between replacement and repair and the age difference between the two groups.

Show evidence (1 reference)

PMID:32420101 SUPPORT Human Clinical

"with valves considered suitable for both replacements"

Operative assessment that the tethered valves required prosthetic replacement.

Diuretic therapy

Action: Pharmacotherapy NCIT:C15986

Agent: diuretic NCIT:C448

Palliative decongestion for the ascites and oedema of right-sided disease and the pulmonary congestion of left-sided disease. It relieves symptoms and does nothing to the scar.

Mechanism Target:

MODULATES Congestive heart failure — Volume reduction lowers filling pressures and relieves congestion without altering the restrictive physiology that causes it.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."

States the palliative role of diuretics explicitly, with no claim of disease modification.

Show evidence (1 reference)

PMID:18596273 SUPPORT Human Clinical

"It has no specific treatment and carries a poor prognosis"

The absence of disease-specific therapy is why management is symptomatic.

Anticoagulation

Action: Pharmacotherapy NCIT:C15986

Agent: anticoagulant NCIT:C263

Directed at the intracardiac thrombus and the atrial fibrillation, both of which are intrinsic to the disease rather than incidental. Like diuresis, it is palliative.

Mechanism Target:

INHIBITS Systemic and pulmonary thromboembolism — Anticoagulation reduces propagation and embolisation of intracardiac thrombus.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."

Names anticoagulation among the palliative measures.

Show evidence (1 reference)

PMID:32420110 SUPPORT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

The thromboembolic complication anticoagulation is directed at.

Antiarrhythmic therapy

Action: Pharmacotherapy NCIT:C15986

Agent: antiarrhythmic agent NCIT:C47793

Rate or rhythm control for the atrial fibrillation that arises on the dilated-atrium substrate. Palliative, and in practice often combined with anticoagulation for the same rhythm.

Mechanism Target:

MODULATES Atrial dilatation and atrial fibrillation — Antiarrhythmic drugs address the rhythm disturbance without affecting the atrial dilatation that generates it.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."

Names antiarrhythmic therapy among the palliative measures.

Show evidence (1 reference)

PMID:32420110 SUPPORT INDIRECT Human Clinical

"complications such as chronic heart failure, thromboembolism and arrhythmia are already present"

The arrhythmia this treatment addresses. Graded INDIRECT because the source names the complication rather than its management.

Prednisolone for recurrent ascites

Action: Pharmacotherapy NCIT:C15986

Agent: prednisolone NCIT:C769

The only randomised trial of a disease-directed medical therapy in this disease, and it was negative. Thirty-five Ugandan patients with grade 2 ascites were randomised to prednisolone 1 mg/kg/day or placebo for up to eight weeks; the drug was safe but did not significantly reduce progression to grade 3 ascites, with a relative risk of 0.70 and a confidence interval crossing one. It is curated here precisely because it is negative: the rationale was the peritoneal inflammation thought to drive the ascites, and the result is the single most relevant piece of evidence against reaching for immunosuppression on the strength of the autoimmune findings elsewhere in this entry. A pilot of 35 with six lost to follow-up cannot exclude a modest benefit, so this is a failure to demonstrate efficacy rather than a demonstration of futility.

Mechanism Target:

INHIBITS Sustained eosinophilia and Th2-skewed immune activation — Corticosteroid suppression of the inflammatory arm was the trial rationale, on the view that peritoneal and endomyocardial inflammation drive the ascites.

Show evidence (1 reference)

PMID:26666319 REFUTE Human Clinical

"There was no statistically significant difference in the overall risk of developing grade 3 ascites over 8 weeks."

The primary endpoint failed, which refutes the proposition that suppressing inflammation with a corticosteroid controls the ascites over this horizon.

Show evidence (3 references)

PMID:26666319 SUPPORT Human Clinical

"Prednisolone was safely administered in this setting."

The safety finding, which is the trial's positive result and the reason a larger study remains feasible.

PMID:26666319 SUPPORT INDIRECT Human Clinical

"Inflammation in other parts of the body such as the peritoneum has been described and may explain the accumulation of ascites, a painful and disabling feature of this disease."

States the mechanistic rationale for the trial, and incidentally supports the entry's characterisation of the ascites as exudative rather than purely congestive. Graded INDIRECT because it is a rationale rather than a result.

PMID:26666319 SUPPORT Human Clinical

"Sixteen study participants were randomised to prednisolone, while nineteen were randomised to placebo. Six were lost to follow up"

The sample size and attrition that bound how much the negative result can be read to exclude. It bounds how much the negative result can be read to exclude rather than measuring efficacy itself.

🌍

Environmental Factors

4

Cassava-based diet with severe protein deprivation

The best-evidenced environmental hypothesis, and the only one with a controlled experimental test behind it. Populations in endemic areas subsist on cassava with little animal protein, and feeding uncooked cassava to African green monkeys under protein restriction reproduces the endomyocardial lesion while a banana diet lacking the same protein does not. That control is what makes this more than a poverty correlation: it separates the cassava from the protein deficiency that accompanies it.

Show evidence (2 references)

PMID:18301727 SUPPORT Human Clinical

"Investigations into nutritional factors in EMF have focused on a possible connection with cassava toxicity."

Identifies cassava toxicity as the focus of nutritional investigation in this disease.

PMID:18301727 SUPPORT Human Clinical

"that cerium-mediated cassava toxicity in the setting of protein deficiency may play a role in the pathogenesis of EMF"

States the combined cerium-plus-cassava-plus-protein-deficiency proposal. It is offered as a possibility rather than an established mechanism.

Mechanism Target:

PREDISPOSES Chronic antigenic or toxic stimulus in a susceptible host — Prolonged cassava ingestion under protein deprivation is the exposure proposed to supply the chronic toxic stimulus that initiates endomyocardial injury.

Show evidence (1 reference)

PMID:8756020 SUPPORT Model Organism

"Changes in the endomyocardium included cell vacuolation, interstitial fibrosis and endocardial thickening by the 130th day in the animals on cassava but the animals on bananas were free from such changes."

The controlled feeding experiment that converts the cassava hypothesis from an epidemiological correlation into an exposure with a demonstrated cardiac effect.

Geochemical exposure to cerium and thorium in monazite soils

No ECTO term is bound. A search of the ECTO exposure hierarchy returned no term for cerium, thorium, monazite, or rare-earth exposure, and binding a broader term such as exposure to soil would assert less than the claim requires while looking more precise than the evidence is.

A regional hypothesis raised to explain the coastal Kerala focus, where endomyocardial fibrosis is prevalent in a zone free of filariasis. It is curated because it is a real and recurring proposal in this literature and because its status is unusually clear: the systematic review states plainly that no empirical study supports it. Recording an unsupported hypothesis with its refuting note is more useful than omitting it, since otherwise the same idea reappears as a lead.

Show evidence (1 reference)

PMID:18301727 NO_EVIDENCE Human Clinical

"No empirical studies have yet come forward to support this theory."

The systematic review's own verdict on the geochemical hypothesis, recorded here so the hypothesis is not mistaken for an established exposure.

Mechanism Target:

PREDISPOSES Chronic antigenic or toxic stimulus in a susceptible host — Soil-derived rare-earth exposure is proposed as the localised toxic stimulus behind regional variation in prevalence.

Show evidence (1 reference)

PMID:18301727 SUPPORT Human Clinical

"Valiathan and Kartha have speculated that cerium or thorium present in monazite deposits may explain regional variation in EMF prevalence in this region"

States the proposed exposure and the geographic observation it was raised to explain. It is explicitly labelled speculation.

Poverty, subsistence farming, and going barefoot

A case-control study from Uganda associated the disease with markers of poverty rather than with any single agent. This is curated as an exposure in its own right because it is the most robust epidemiological signal in the disease and because the mechanism is genuinely unresolved: poverty could act through diet, through helminth exposure from going unshod, through reduced access to care, or through all three, and the studies to date cannot separate them.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Current evidence supports a multifactorial model in which nutritional deficiencies, infections with associated eosinophilia, immune dysregulation, and genetic predisposition interact within adverse socioeconomic settings to promote progressive endocardial fibrosis"

Places socioeconomic setting as the context within which the other exposures act, which is why it is modelled as an exposure rather than as a confounder.

Mechanism Target:

PREDISPOSES Chronic antigenic or toxic stimulus in a susceptible host — Socioeconomic deprivation is the setting in which the nutritional and infectious exposures co-occur, and is itself the most consistently reported association.

Show evidence (1 reference)

PMID:32420110 SUPPORT Human Clinical

"Dietary, environmental and infectious factors seem to combine in susceptible individuals to give rise to an inflammatory process that leads to endomyocardial damage and scar formation."

States the combined-exposure model that this entry represents, with the co-occurrence that makes the individual factors hard to separate.

Chronic helminth and malarial infection

Schistosomiasis and filariasis are common in endemic zones and are the classical proposed source of the eosinophilia. The evidence undercuts a simple version of the hypothesis in a specific way worth preserving: parasite load does not consistently differ between cases and controls, which is what turns eosinophilia from a universal initiator into an amplifier acting on some other primary insult.

Show evidence (2 references)

PMID:41399600 REFUTE Human Clinical

"parasitic load does not consistently differ between EMF and control subjects"

Refutes a straightforward parasite-burden model of causation, and is the observation behind treating eosinophilia as an amplifier rather than an initiator.

PMID:18301727 SUPPORT Human Clinical

"While the prevalence of plasmodial species does not match the geographic distribution of EMF, these findings point to changes in immunity as a possible pathway from malaria to endocardial disease."

States both the geographic mismatch that argues against malaria as a cause and the immune-alteration pathway that keeps it in contention.

Mechanism Target:

PREDISPOSES Sustained eosinophilia and Th2-skewed immune activation — Chronic helminth infection is the proposed driver of the sustained eosinophilia on which the accepted mechanism depends.

Show evidence (1 reference)

PMID:41399600 SUPPORT Human Clinical

"Parasitic infections-particularly schistosomiasis and filariasis-are common cofactors in endemic zones"

Names the specific parasites proposed as cofactors. Cofactor status is weaker than the causal role the eosinophil model would need.

🔬

Biochemical Markers

4

Circulating anti-myocardial IgG (INCREASED)

Show evidence (1 reference)

PMID:20422043 SUPPORT Human Clinical

"EMF patients showed greater frequency and reactivity of IgG antibodies against myocardial proteins of molecular weights 35 kD, 42 kD and 70 kD"

Identifies the specific antigenic targets and the direction of the difference from controls.

Plasma interleukin-4 (INCREASED)

Show evidence (1 reference)

PMID:25303100 SUPPORT Human Clinical

"plasma levels of IL-10, IL-4, and TNF-α were significantly higher than those of controls"

The case-control comparison establishing the elevation.

Plasma interleukin-10 (INCREASED)

Show evidence (1 reference)

PMID:25303100 SUPPORT Human Clinical

"IL-4 and IL-10 may have been upregulated as a homeostatic mechanism to buffer both production and deleterious cardiovascular effects of pro-inflammatory cytokines"

The authors' alternative reading of their own finding, recorded so the cytokine profile is not over-interpreted as causal.

Plasma tumour necrosis factor alpha (INCREASED)

Show evidence (1 reference)

PMID:25303100 SUPPORT Human Clinical

"the detection of increased levels of TNF-α may be secondary to the cardiovascular involvement observed in these patients"

Records the elevation together with the authors' own hedge about its direction, which is why no directional claim is made here.

🔬

Diagnosis

3

Transthoracic echocardiography

The primary diagnostic tool, and the only practical one in the settings where the disease occurs. It shows apical obliteration, endocardial thickening, subvalvular tethering with atrioventricular regurgitation, and biatrial dilatation, and it detects asymptomatic disease that would otherwise be invisible. Standardised criteria and a severity score make it usable for population screening.

echocardiography NCIT:C16525

Show evidence (2 references)

PMID:32420110 SUPPORT Human Clinical

"Our research has shown that echocardiographic screening using standard criteria adds sensitivity and precision to the diagnosis, particularly in asymptomatic disease, providing an opportunity for longitudinal community-based research."

Establishes standardised echocardiographic screening as the method that made asymptomatic disease detectable.

PMID:18596273 SUPPORT Human Clinical

"We used transthoracic echocardiography to determine the prevalence of endomyocardial fibrosis in a rural area of Mozambique."

The method used in the population study that defined the disease's true frequency.

Cardiac magnetic resonance imaging

Superior tissue characterisation, able to separate the inflammatory from the fibrotic stage and to demonstrate the subendocardial scar and adherent thrombus. Its practical relevance in endemic settings is limited by availability, which is itself part of why the disease is under-studied.

magnetic resonance imaging NCIT:C16809

Show evidence (2 references)

PMID:41399600 SUPPORT Human Clinical

"Echocardiography remains the primary diagnostic tool, especially in resource-limited settings, while cardiac MRI offers superior tissue characterization."

States the division of labour between the two imaging modalities and the reason for it.

PMID:34172539 SUPPORT Human Clinical

"New imaging modalities such as strain imaging and specific sequences in MRI offer the perspective of detecting subtle perturbations and distinguishing inflammatory versus fibrotic stages."

Documents the specific capability that matters mechanistically, separating the reversible from the irreversible stage.

Endomyocardial biopsy

Occasionally used, chiefly where an eosinophilic cause is suspected but the blood count is not informative. Its yield is limited in a characteristic way: by the time fibrosis is established the eosinophils have degranulated or been replaced, so a negative biopsy does not exclude an eosinophilic origin. That is a mechanistically informative limitation, not just a technical one.

endomyocardial biopsy NCIT:C51674

Show evidence (1 reference)

PMID:34172539 SUPPORT Human Clinical

"Endomyocardial biopsy may help in difficult settings, namely, when blood eosinophilia is not prominent, but may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"

States both the indication and the specific reason the test under-detects the mechanism it is looking for.

📈

Progression

4

Acute necrotic stage

Davies stage one, lasting up to about five months: eosinophilic infiltration of the subendocardium with myocyte necrosis and troponin release. In hypereosinophilic syndrome this stage is generally asymptomatic and detectable by troponin and cardiac magnetic resonance. In tropical endomyocardial fibrosis it is almost never observed, because patients in endemic areas do not reach care until heart failure has developed.

Show evidence (1 reference)

PMID:34172539 SUPPORT Human Clinical

"At the early generally asymptomatic stage, related to subendocardial eosinophilic infiltrates, elevation of the biomarker of cardiac damage (serum troponin) and cardiac MRI are the best tools for diagnosis."

Characterises the early stage and the tools that detect it.

Thrombotic stage

Davies stage two, beginning around ten months and running over years: mural thrombus forms over the damaged endocardium at the apex and beneath the posterior mitral leaflet, and is organised rather than lysed.

Show evidence (1 reference)

PMID:34172539 SUPPORT Human Clinical

"As disease progresses, patients typically develop intracardiac mural thrombi"

Places mural thrombus as the intermediate stage of the sequence.

Fibrotic stage

Davies stage three: dense acellular endocardial scar, restrictive physiology, and atrioventricular regurgitation. This stage is irreversible, and it is where nearly all diagnosis happens. One-third to one-half of patients with advanced disease die within two years.

Show evidence (1 reference)

PMID:31414216 SUPPORT Human Clinical

"Medical care currently remains very challenging as one-third to half of patients with an advanced disease die within 2 years."

Quantifies the prognosis of the fibrotic stage.

Subclinical detected disease

Population echocardiographic screening reveals a large reservoir of the disease that never reaches clinical attention. In rural Mozambique, only 22.7 percent of screen-detected cases were symptomatic, and most had mild-to-moderate structural abnormalities. Whether these represent early disease destined to progress, or a stable non-progressive form, is unknown and is arguably the most consequential open question about the natural history.

Show evidence (1 reference)

PMID:18596273 SUPPORT Human Clinical

"Most affected subjects had mild-to-moderate structural and functional echocardiographic abnormalities. Only 48 persons with endomyocardial fibrosis (22.7%) were symptomatic."

Documents the large asymptomatic reservoir revealed by population screening.

📊

Prevalence

2

Rural Mozambique, all ages, echocardiographic population screen

Point Prevalence 19800.0 per 100,000 >1 in 1,000

An estimated 19.8 percent of a random cluster sample of 1063 subjects had echocardiographic endomyocardial fibrosis, with a peak of 28.1 percent in the 10 to 19 year age group. This is the figure that reframed the disease from a rare referral diagnosis to a major endemic public-health problem, and it is a screen-detected prevalence rather than a clinical one.

Show evidence (1 reference)

PMID:18596273 SUPPORT Human Clinical

"The estimated overall prevalence of endomyocardial fibrosis was 19.8%, or 211 of 1063 subjects"

The primary prevalence estimate from the only population-based study.

Kampala, Uganda, patients referred for echocardiography

Point Prevalence >1 in 1,000

The disease accounts for 20 percent of heart disease patients referred for echocardiography in Kampala. This is a referral-population figure, not a population prevalence, and is recorded to document the clinical burden in endemic centres.

Show evidence (1 reference)

PMID:18301727 SUPPORT Human Clinical

"In Kampala, the disease accounts for 20% of heart disease patients referred for echocardiography."

Quantifies the referral burden in a historically endemic centre.

⚖️

Clinical Burden

High

A progressive, incurable cardiomyopathy of children and young adults, presenting in New York Heart Association class III or IV in nearly all diagnosed cases, with one-third to one-half of advanced patients dead within two years. There is no disease-specific drug. The only intervention that prolongs survival is open-heart surgery, which carries high operative risk and is unavailable to the overwhelming majority of affected people, who live in rural low-income settings.

The burden is inseparable from the setting. Population screening in rural Mozambique found nearly one in five people affected, with a peak in adolescence, which makes this a major endemic cause of heart failure in the affected regions rather than a rare disease in the usual sense. Late diagnosis is driven by lack of clinical awareness and poor access to care, so the complications of heart failure, thromboembolism, and arrhythmia are typically already present when the disease is first recognised.

Show evidence (3 references)

PMID:31414216 SUPPORT Human Clinical

"Medical care currently remains very challenging as one-third to half of patients with an advanced disease die within 2 years."

Quantifies mortality in advanced disease.

PMID:32420110 SUPPORT Human Clinical

"Lack of awareness by health professionals and low access to health care determine late diagnosis, when complications such as chronic heart failure, thromboembolism and arrhythmia are already present."

Identifies the access and awareness failures that determine when the disease is caught.

PMID:18596273 SUPPORT Human Clinical

"It has no specific treatment and carries a poor prognosis, since most patients present with advanced heart failure."

States the absence of specific therapy and the presentation stage together.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Endomyocardial Fibrosis:

Constrictive pericarditis

Overlapping Features The classic mimic, since both produce restrictive filling with preserved systolic function and prominent right-sided congestion. Imaging separates them by locating the lesion: a thickened, adherent pericardium in constriction versus a thickened endocardium with an obliterated apex and tethered subvalvular apparatus in endomyocardial fibrosis. The distinction matters because pericardiectomy and endocardial decortication are different operations.

Show evidence (1 reference)

PMID:41399600 SUPPORT INDIRECT Human Clinical

"Diagnosis is often delayed due to overlap with other causes of heart failure and limited access to advanced imaging."

States the diagnostic-overlap problem this differential belongs to. Graded INDIRECT because constrictive pericarditis is not named specifically.

Hypereosinophilic syndrome with cardiac involvement

Overlapping Features Löffler endocarditis produces an endocardial lesion that is histologically and echocardiographically indistinguishable from tropical endomyocardial fibrosis at the fibrotic stage. The separation is by context, not by cardiac appearance: a documented marked eosinophilia, often with an identifiable clonal or reactive cause, versus an endemic tropical setting with no eosinophilia at presentation. This is more than a differential, since it is the disease from which the mechanism of endomyocardial fibrosis is inferred.

Show evidence (1 reference)

PMID:31414216 SUPPORT Human Clinical

"its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome"

States the pathologic indistinguishability that makes this simultaneously a differential and a mechanistic model.

Rheumatic mitral valve disease

Overlapping Features Also common in the same populations and also presents with severe mitral regurgitation in a young patient. The discriminating feature is the ventricle rather than the valve: rheumatic disease damages the leaflets and commissures with a normal ventricular apex, whereas endomyocardial fibrosis leaves the leaflets structurally intact and tethers them from an obliterated, scarred apex.

Show evidence (1 reference)

PMID:32420101 SUPPORT INDIRECT Human Clinical

"The echocardiographic changes corresponded well to the findings on surgery and histopathology."

Supports echocardiography's ability to characterise the ventricular lesion that distinguishes the two. Graded INDIRECT because rheumatic disease is not the comparator in this study.

🧫

Experimental Models

3

Cassava-fed Cercopithecus aethiops with protein deprivation OTHER

The only animal model that reproduces the human lesion from a proposed natural exposure rather than from a laboratory insult. Three African green monkeys were fed uncooked cassava and three uncooked banana, and hearts were taken for histology as health deteriorated. Cassava-fed animals developed endocardial thickening, interstitial fibrosis, papillary muscle fibrosis, and apical left ventricular fibrosis; banana-fed animals did not. The banana arm is the crucial control, because it was also protein-free, which separates a cassava-specific effect from generic protein deprivation. Limitations are real: n is three per arm, the endpoint is histology in a deteriorating animal rather than a defined disease state, and no eosinophilic phase was described, so the model supports the nutritional arm without addressing the eosinophil arm at all.

Organism

Chlorocebus aethiops NCBITaxon:9534

Publication

PMID:8756020

Pathograph links

Chronic antigenic or toxic stimulus in a susceptible host The model instantiates the proposed dietary toxic exposure directly.

Dense endocardial fibrous scar The model reproduces the defining endocardial lesion, including its apical and papillary distribution.

Show evidence (2 references)

PMID:8756020 SUPPORT Model Organism

"By the 160th day, the former exhibited marked thickening of the endocardium, interstitial fibrosis, fibrous septa formation, pappillary muscle fibrosis as well as apical fibrosis of the left ventricle, which findings occur in the human disease."

Documents recapitulation of the specific human lesion, including its apical and papillary distribution.

PMID:8756020 SUPPORT Model Organism

"the animals on bananas, which also lacked protein did not develop similar changes"

The control that distinguishes a cassava-specific effect from protein deprivation alone, and the single most informative result in the model.

Plantain and serotonin dietary models OTHER

A refuted hypothesis, retained because the refutation is the useful part. High urinary 5-hydroxyindole-acetic acid in West and East Africans suggested that serotonin from a plantain-based diet caused the disease. Plantains were fed to guinea pigs, rats, and Patas monkeys, and typical lesions did not appear; serum 5-hydroxytryptamine failed to rise in patients fed plantains in Nigeria; and the line of inquiry stopped. Curating this prevents the hypothesis being rediscovered as a lead, and it shows that this disease's model literature contains genuine negative results rather than only untested proposals.

Publication

PMID:18301727

Pathograph links

Chronic antigenic or toxic stimulus in a susceptible host The models tested a dietary serotonin exposure as the proposed toxic stimulus, and failed to reproduce the disease.

Show evidence (2 references)

PMID:18301727 REFUTE Model Organism

"They could not reproduce typical EMF lesions."

The negative result in guinea pigs, rats, and Patas monkeys that ended the serotonin hypothesis.

PMID:18301727 REFUTE Human Clinical

"Early enthusiasm for the role of serotonin in a plantain-based diet waned by the early 1970s"

Records the abandonment of the hypothesis, which together with the animal negative is why this model is curated as a refutation.

Fibroblast and cardiomyocyte coculture CO_CULTURE

The only cell-based system used for this disease, and explicitly not a disease model. Cocultures of RT3 fibroblasts with SV40-transformed RL-14 cardiomyocytes show fibroblast migration, vimentin upregulation, inhibition of cardiomyocyte proliferation, and distortion of cardiomyocyte morphology. The published limitations are unusually candid and are reproduced here because they matter for how the results should be read: the cell lines are artificial, there are no eosinophils and no endothelial cells in the system, and the extracellular matrix is not physiologic. Since eosinophils and endocardial endothelium are precisely the cells the accepted mechanism turns on, this system cannot speak to the initiating injury at all.

Publication

PMID:41399600

Pathograph links

Fibroblast activation and excessive collagen deposition The coculture models the fibroblast-cardiomyocyte interaction of the fibrogenic step only, downstream of the injury it cannot represent.

Show evidence (2 references)

PMID:41399600 SUPPORT INDIRECT In Vitro

"demonstrating fibroblast migration, vimentin upregulation, inhibition of cardiomyocyte proliferation, and morphologic distortion of cardiomyocytes"

The findings the system produces. Graded INDIRECT because they are mechanistic proxies rather than disease recapitulation.

PMID:41399600 REFUTE In Vitro

"However, these models serve only as mechanistic proxies rather than true EMF disease models."

The authors' explicit statement that this is not a disease model, recorded so the coculture results are not read as evidence about the disease itself.

{ }

Source YAML

click to show

name: Endomyocardial Fibrosis
creation_date: '2026-08-09T00:00:00Z'
category: Complex
description: >
  Endomyocardial fibrosis is the most common restrictive cardiomyopathy worldwide and a
  disease of poverty, endemic to equatorial Africa, South Asia, and parts of South America.
  Dense fibrous scar deposits on the endocardium of the apex and inflow tract of one or both
  ventricles, obliterating cavity volume and tethering the papillary muscles and chordae so
  that the atrioventricular valves leak. The result is severe restrictive physiology with
  atrioventricular regurgitation and relatively preserved ejection fraction, presenting as
  progressive heart failure in children and young adults. The prevailing mechanistic model
  runs from a chronic antigenic or toxic stimulus, through sustained eosinophilia in a
  genetically susceptible host, to eosinophil-granule-mediated endocardial injury, mural
  thrombosis, and finally organisation into acellular fibrous scar, following the three
  stages Davies described. That model is inferred largely from hypereosinophilic syndrome,
  in which the same endocardial lesion is directly documented, rather than from tropical
  endomyocardial fibrosis itself, where the acute eosinophilic phase is almost never caught.
  Its unique geography remains unexplained after eight decades, and it is the clearest
  example in this knowledge base of a disease whose mechanism is limited by where it occurs
  rather than by its biology.
disease_term:
  preferred_term: endomyocardial fibrosis
  term:
    id: MONDO:0006746
    label: endomyocardial fibrosis
parents:
- Restrictive cardiomyopathy
synonyms:
- Davies disease
- Tropical endomyocardial fibrosis
- African endomyocardial fibrosis
- Endomyocardial sclerosis
- Obscure African cardiomyopathy
pathophysiology:
- name: Chronic antigenic or toxic stimulus in a susceptible host
  description: >
    The initiating exposure is not established. Chronic helminth infection, malaria,
    cassava-based diets with protein deprivation, and geochemical exposures such as cerium in
    monazite-rich soils have all been proposed, and none accounts for the disease's
    distribution. The strongest structural observation is negative: hypotheses that explain
    why the disease occurs where it does fail to explain why it does not occur in other
    regions with the same parasite burden or the same diet. What is well supported is that
    exposure alone is insufficient, since only a minority of people living in identical
    conditions develop the disease.
  biological_scale: ORGANISM
  role: trigger
  conforms_to: "fibrotic_response#Tissue Injury"
  downstream:
  - target: Sustained eosinophilia and Th2-skewed immune activation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      A chronic antigenic stimulus in a susceptible host is proposed to drive persistent
      eosinophilia, which is the first step of the mechanistic model.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Dietary, environmental and infectious factors seem to combine in susceptible individuals to give rise to an inflammatory process that leads to endomyocardial damage and scar formation."
      explanation: States the whole proposed chain compactly, with the honest hedging the evidence supports.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution."
    explanation: The systematic review's central negative conclusion, which is why this node is deliberately unspecific.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "its etiology remains poorly understood, with proposed contributors including malnutrition, parasitic infections, hypereosinophilia, and genetic predisposition"
    explanation: Enumerates the candidate exposures without privileging any, matching the state of the evidence.
- name: Sustained eosinophilia and Th2-skewed immune activation
  description: >
    Persistent eosinophilia is the pivot of the accepted model. In hypereosinophilic
    syndrome, where the eosinophil count is by definition high and the cardiac disease is
    followed prospectively, eosinophil-mediated endomyocardial damage is directly
    established. In tropical endomyocardial fibrosis, eosinophilia is variably present and
    typically absent by the time the fibrotic stage is diagnosed, so the inference runs
    backwards from a shared end-stage lesion. That asymmetry is real and is curated as such
    rather than smoothed over.
  biological_scale: ORGANISM
  role: mechanism
  conforms_to: "fibrotic_response#Inflammatory Recruitment and Amplification"
  cell_types:
  - preferred_term: Eosinophil
    term:
      id: CL:0000771
      label: eosinophil
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
    modifier: INCREASED
  downstream:
  - target: Eosinophil degranulation and endocardial injury
    causal_link_type: DIRECT
    description: >
      Eosinophils infiltrate the subendocardium and release granule proteins that damage
      endothelium and subendocardial myocytes.
    evidence:
    - reference: PMID:34172539
      reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "At the early generally asymptomatic stage, related to subendocardial eosinophilic infiltrates, elevation of the biomarker of cardiac damage (serum troponin) and cardiac MRI are the best tools for diagnosis."
      explanation: Establishes the subendocardial eosinophilic infiltrate as the earliest cardiac stage, with troponin release as evidence of concurrent myocardial damage.
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eosinophil-mediated endomyocardial damage is a well-known complication in patients with hypereosinophilic syndromes (HES)."
    explanation: The direct evidence for eosinophil-mediated endomyocardial damage comes from hypereosinophilic syndrome, which is the model the tropical disease is read through.
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although its pathogenesis and etiology are not fully understood, its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome."
    explanation: >-
      States the pathologic resemblance that licenses the inference from
      hypereosinophilic syndrome to tropical endomyocardial fibrosis. Graded INDIRECT
      because resemblance is not identity.
  - reference: PMID:25303100
    reference_title: "Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We found that TNF-α, IL-6, IL-4, and IL-10 were each detected in at least 74% of tested sera, and plasma levels of IL-10, IL-4, and TNF-α were significantly higher than those of controls."
    explanation: Direct measurement of the Th2 cytokines IL-4 and IL-10 in 27 tropical endomyocardial fibrosis patients against healthy controls, which is what supports the Th2 half of this node's claim.
  - reference: PMID:25303100
    reference_title: "Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mixed pro- and anti-inflammatory/Th2circulating cytokine profile in EMF is consistent with the presence of a persistent inflammatory stimulus."
    explanation: The authors' own reading of the profile as Th2-skewed and as evidence of a persistent stimulus, which is the state this node asserts. Note the source's own typographical run-together of Th2 and circulating, reproduced verbatim.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This suggests eosinophilia acts as a disease amplifier rather than a universal initiator."
    explanation: >-
      Qualifies the causal weight of eosinophilia in this node. It constrains how much
      causal weight eosinophilia can carry, which is why the eosinophil arm is curated
      as necessary-but-not-sufficient.
- name: Eosinophil degranulation and endocardial injury
  description: >
    Degranulating eosinophils release cationic granule proteins into the subendocardium,
    injuring endocardial endothelium and the subendocardial layer of myocytes. This is
    Davies stage one, the acute necrotic phase, lasting some months. It is the stage almost
    never observed in tropical endomyocardial fibrosis, because patients in endemic areas do
    not present until they are in heart failure, and it is the single largest gap in the
    evidence for this disease.
  biological_scale: CELLULAR
  role: mechanism
  cell_types:
  - preferred_term: Eosinophil
    term:
      id: CL:0000771
      label: eosinophil
  - preferred_term: Endocardial endothelial cell
    term:
      id: CL:0002350
      label: endocardial cell
  biological_processes:
  - preferred_term: eosinophil degranulation
    term:
      id: GO:0043308
      label: eosinophil degranulation
    modifier: INCREASED
  locations:
  - preferred_term: Endocardium
    term:
      id: UBERON:0002165
      label: endocardium
  downstream:
  - target: Mural thrombus formation on the damaged endocardium
    causal_link_type: DIRECT
    description: >
      The denuded, injured endocardial surface becomes thrombogenic, and mural thrombus
      forms over it during the second stage.
    evidence:
    - reference: PMID:34172539
      reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "As disease progresses, patients typically develop intracardiac mural thrombi and may experience variable degrees of heart failure due to valve damage and/or subendocardial fibrosis"
      explanation: Sets out the ordered progression from eosinophilic infiltrate to mural thrombus to subendocardial fibrosis and valve damage.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypereosinophilia likely contributes to early myocardial necrosis through eosinophil granule proteins (major basic protein, eosinophil peroxidase), initiating an inflammatory-fibrotic cascade"
    explanation: Names the specific granule proteins and the injury they cause, in a source about endomyocardial fibrosis itself rather than about hypereosinophilic syndrome.
  - reference: PMID:38540269
    reference_title: "Eosinophilic Myocarditis: From Bench to Bedside."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ranging from mild asymptomatic disease to multifocal widespread infiltrates associated with myocardial necrosis, thrombotic complications, and endomyocardial fibrosis"
    explanation: Links eosinophilic infiltration to myocardial necrosis, thrombosis, and endomyocardial fibrosis as a single severity spectrum.
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"
    explanation: >-
      Documents that eosinophil degranulation itself erases the diagnostic evidence of
      eosinophilic infiltration, which is exactly why the acute stage is under-observed.
      Graded INDIRECT because the statement is about biopsy yield rather than the
      mechanism directly.
- name: Mural thrombus formation on the damaged endocardium
  description: >
    Davies stage two, beginning around ten months and running over years. Thrombus deposits
    on the injured endocardial surface, preferentially at the ventricular apex and beneath the
    posterior mitral leaflet, and is then organised rather than lysed. This is the step that
    converts an inflammatory injury into a structural one, and it is also the source of the
    systemic and pulmonary thromboembolism that complicates the disease independently.
  biological_scale: TISSUE
  role: mechanism
  biological_processes:
  - preferred_term: blood coagulation
    term:
      id: GO:0007596
      label: blood coagulation
    modifier: INCREASED
  locations:
  - preferred_term: Endocardium
    term:
      id: UBERON:0002165
      label: endocardium
  downstream:
  - target: Fibroblast activation and excessive collagen deposition
    causal_link_type: DIRECT
    description: >
      Organisation of the mural thrombus recruits and activates fibroblasts, which lay down
      collagen in the subendocardial layer.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: "give rise to an inflammatory process that leads to endomyocardial damage and scar formation"
      explanation: >-
        States the inflammation-to-scar transition. Graded INDIRECT because the
        thrombus-organisation step specifically is not itemised.
  - target: Systemic and pulmonary thromboembolism
    causal_link_type: DIRECT
    description: >
      Fragments of intracardiac thrombus embolise.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
      explanation: Names thromboembolism among the complications present at the typical late point of diagnosis.
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "As disease progresses, patients typically develop intracardiac mural thrombi"
    explanation: Places mural thrombus formation as the intermediate stage of the eosinophilic endocardial disease sequence.
- name: Anti-myocardial autoantibody response
  description: >
    Circulating IgG against myocardial proteins is present in about half of patients and in
    a tenth of controls, and its intensity tracks disease activity. It is curated as a
    parallel amplifying arm rather than as a step in the main chain, because the direction of
    causation is not established: antibodies could sustain injury after the eosinophilic
    stimulus has gone, or could simply mark exposure of intracellular myocardial antigens by
    injury that has already occurred. The distinction matters clinically, since only the
    first reading would justify immunosuppression.
  biological_scale: ORGANISM
  role: mechanism
  downstream:
  - target: Fibroblast activation and excessive collagen deposition
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Continuing autoimmune myocardial injury is proposed to perpetuate the fibrogenic
      stimulus after the initiating eosinophilia has resolved.
    evidence:
    - reference: PMID:20422043
      reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF"
      explanation: >-
        Establishes the correlation with disease activity that motivates the proposed
        edge. The authors explicitly stop short of asserting causation.
  evidence:
  - reference: PMID:20422043
    reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IgG reactivity against myocardial proteins was stronger and more frequent in patients with EMF when compared to controls (30/56; 53.6% vs. 1/10; 10%, respectively)."
    explanation: Quantifies the autoantibody finding against healthy controls in 56 patients.
  - reference: PMID:20422043
    reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Further research is needed to clarify the role of autoimmunity in the pathogenesis of EMF."
    explanation: The authors' own statement that the causal role is unresolved, which is why this node is curated as a parallel arm.
- name: Fibroblast activation and excessive collagen deposition
  description: >
    Subendocardial fibroblasts are activated and deposit collagen and other matrix, the
    generic fibrogenic step this disease shares with organ fibrosis elsewhere. What is
    unusual is the trigger, an intraluminal eosinophil-driven injury with an organising
    thrombus rather than a parenchymal insult, and the site, a thin subendothelial layer
    rather than the interstitium of the organ.
  biological_scale: CELLULAR
  role: mechanism
  conforms_to: "fibrotic_response#Mesenchymal Cell Activation"
  cell_types:
  - preferred_term: Cardiac fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  biological_processes:
  - preferred_term: fibroblast activation
    term:
      id: GO:0072537
      label: fibroblast activation
    modifier: INCREASED
  - preferred_term: collagen fibril organization
    term:
      id: GO:0030199
      label: collagen fibril organization
    modifier: INCREASED
  downstream:
  - target: Dense endocardial fibrous scar
    causal_link_type: DIRECT
    description: >
      Sustained matrix deposition produces the dense acellular fibrocollagenous endocardial
      thickening that defines the disease.
    evidence:
    - reference: PMID:31414216
      reference_title: "Endomyocardial fibrosis: past, present, and future."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "It is characterized by fibrotic thickening of the endocardium and myocardium of one or both ventricles."
      explanation: The defining structural lesion this step produces.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A key feature is fibroblast overactivation leading to excessive extracellular matrix deposition, primarily fibrillar collagen, which replaces normal myocardium and results in myocardial stiffness and electromechanical uncoupling."
    explanation: The direct statement of this node, naming the cell, the matrix product, and the mechanical consequence.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Persistent activation of these pathways amplifies pro-fibrotic signaling (e.g., SMAD2/3 and YAP/TAZ), leading to chronic endocardial scarring"
    explanation: Names the intracellular pro-fibrotic signalling that sustains the activated state.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "an inflammatory process that leads to endomyocardial damage and scar formation"
    explanation: States the inflammation-to-scar transition that this node represents.
- name: Dense endocardial fibrous scar
  description: >
    Davies stage three and the irreversible end-state. The endocardium thickens to
    millimetres of dense, largely acellular fibrocollagenous tissue, measured at a mean of
    three millimetres in an operative series, with a lymphocyte-predominant infiltrate and
    subendocardial neovascularisation. The myocardium beneath is comparatively spared, which
    is why systolic function is preserved and why surgical decortication is anatomically
    feasible at all.
  biological_scale: TISSUE
  role: consequence
  conforms_to: "fibrotic_response#Excessive ECM Deposition"
  locations:
  - preferred_term: Endocardium
    term:
      id: UBERON:0002165
      label: endocardium
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: INCREASED
  downstream:
  - target: Apical and inflow-tract cavity obliteration
    causal_link_type: DIRECT
    description: >
      Scar fills the trabecular recesses of the apex and inflow tract, reducing cavity volume.
    evidence:
    - reference: PMID:31414216
      reference_title: "Endomyocardial fibrosis: past, present, and future."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Extensive fibrosis of the ventricular endocardium causing architectural distortion, impaired filling, and valvular insufficiency defines the disease."
      explanation: Names architectural distortion, impaired filling, and valve insufficiency as the three structural consequences of the scar.
  - target: Papillary muscle and chordal tethering
    causal_link_type: DIRECT
    description: >
      Scar extends onto and around the subvalvular apparatus, fixing the papillary muscles
      and chordae to the ventricular wall.
    evidence:
    - reference: PMID:32420101
      reference_title: "Endomyocardial fibrosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All but one female patient with mild ventricular lesions and no valvular involvement had severe atrioventricular valve regurgitation"
      explanation: Operative series showing that atrioventricular valve regurgitation accompanies ventricular involvement in all but the mildest cases.
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mean endocardial thickness was 3,000 (±1519) µm."
    explanation: Direct operative measurement of the scar thickness in 55 patients.
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The echocardiographic changes corresponded well to the findings on surgery and histopathology."
    explanation: Confirms that the echocardiographically defined lesion is the same lesion seen at surgery and on histology.
- name: Apical and inflow-tract cavity obliteration
  description: >
    Fibrous obliteration of the apex and inflow tract removes the part of the ventricle that
    would otherwise accommodate diastolic filling. The apex takes on the characteristic
    rounded, retracted appearance on echocardiography that gives the diagnosis.
  biological_scale: TISSUE
  role: consequence
  conforms_to: "fibrotic_response#Architectural Distortion and Organ Dysfunction"
  locations:
  - preferred_term: Left ventricle
    term:
      id: UBERON:0002084
      label: heart left ventricle
  - preferred_term: Right ventricle
    term:
      id: UBERON:0002080
      label: heart right ventricle
  downstream:
  - target: Restrictive diastolic physiology
    causal_link_type: DIRECT
    description: >
      Loss of compliant cavity volume raises filling pressures for any given volume.
    evidence:
    - reference: PMID:31414216
      reference_title: "Endomyocardial fibrosis: past, present, and future."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Extensive fibrosis of the ventricular endocardium causing architectural distortion, impaired filling, and valvular insufficiency defines the disease."
      explanation: Links the architectural distortion directly to impaired filling.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Characterized by fibrotic thickening of the ventricular endocardium, EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure."
    explanation: The full downstream sequence from the fibrous lesion to heart failure.
- name: Papillary muscle and chordal tethering
  description: >
    The subvalvular apparatus is drawn into and immobilised by the scar, so the leaflets
    cannot coapt. The mitral regurgitation of this disease is therefore mechanical and
    subvalvular in origin, not a leaflet disease, which is why valve repair addresses the
    tethering rather than the leaflets and why decortication is done at the same operation.
  biological_scale: TISSUE
  role: consequence
  locations:
  - preferred_term: Papillary muscle of heart
    term:
      id: UBERON:0002494
      label: papillary muscle of heart
  downstream:
  - target: Atrioventricular valve regurgitation
    causal_link_type: DIRECT
    description: >
      Tethered chordae prevent leaflet coaptation, producing mitral or tricuspid
      regurgitation.
    evidence:
    - reference: PMID:32420101
      reference_title: "Endomyocardial fibrosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All but one female patient with mild ventricular lesions and no valvular involvement had severe atrioventricular valve regurgitation"
      explanation: Operative confirmation that ventricular scar and valve regurgitation travel together.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"
    explanation: Names atrioventricular valve dysfunction as a defining consequence alongside the restrictive physiology.
- name: Atrioventricular valve regurgitation
  description: >
    Mitral, tricuspid, or both, depending on which ventricle is involved, and typically
    severe by the time of presentation. It compounds the restrictive physiology by loading
    atria that are already facing high ventricular filling pressures.
  biological_scale: ORGANISM
  role: consequence
  locations:
  - preferred_term: Mitral valve
    term:
      id: UBERON:0002135
      label: mitral valve
  - preferred_term: Tricuspid valve
    term:
      id: UBERON:0002134
      label: tricuspid valve
  downstream:
  - target: Atrial dilatation and atrial fibrillation
    causal_link_type: DIRECT
    description: >
      Regurgitant volume dilates the atria, creating the substrate for atrial fibrillation.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
      explanation: >-
        Names arrhythmia among the established complications. Graded INDIRECT because
        the atrial-dilatation mechanism is not itemised.
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "had severe atrioventricular valve regurgitation with valves considered suitable for both replacements"
    explanation: Operative series documenting the severity of the regurgitation.
- name: Restrictive diastolic physiology
  description: >
    Ventricles that cannot fill, with preserved contraction of what myocardium remains. This
    is the haemodynamic signature of the disease and the reason it sits in the restrictive
    rather than the dilated or hypertrophic category, and it explains why ejection fraction
    is a useless measure of severity here.
  biological_scale: ORGANISM
  role: consequence
  downstream:
  - target: Congestive heart failure
    causal_link_type: DIRECT
    description: >
      High filling pressures transmit backwards, producing systemic venous congestion in
      right-sided disease and pulmonary congestion in left-sided disease.
    evidence:
    - reference: PMID:41399600
      reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"
      explanation: The restrictive-physiology-to-heart-failure edge stated directly.
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Endomyocardial fibrosis is the most common restrictive cardiomyopathy worldwide."
    explanation: Places the disease in the restrictive category, and quantifies its global significance within it.
- name: Atrial dilatation and atrial fibrillation
  description: >
    Massive biatrial dilatation is characteristic, driven by both the restrictive ventricles
    and the valve regurgitation, and brings atrial fibrillation with its own thromboembolic
    risk on top of the intracardiac mural thrombus already present.
  biological_scale: ORGANISM
  role: consequence
  downstream:
  - target: Systemic and pulmonary thromboembolism
    causal_link_type: DIRECT
    description: >
      Atrial fibrillation in dilated atria adds a second source of intracardiac thrombus.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
      explanation: >-
        Lists arrhythmia and thromboembolism together as coexisting complications.
        Graded INDIRECT because the causal link between them is not asserted in the
        source.
  evidence:
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: Documents arrhythmia as an established complication at the time of typical late diagnosis.
- name: Systemic and pulmonary thromboembolism
  description: >
    Embolisation from ventricular mural thrombus or from fibrillating dilated atria, and one
    of the reasons anticoagulation features in palliative management of a disease with no
    disease-modifying drug.
  biological_scale: ORGANISM
  role: consequence
  evidence:
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: Names thromboembolism among the complications typically present at diagnosis.
- name: Congestive heart failure
  description: >
    The presenting syndrome in nearly all diagnosed cases, and typically advanced. In an
    operative series all but one of 55 children were in New York Heart Association class III
    or IV at the time of surgery, which is a statement about access to care as much as about
    the disease.
  biological_scale: ORGANISM
  role: consequence
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All but one patient was in NYHA functional class III or IV at the time of surgery."
    explanation: Quantifies how advanced the heart failure is at the point of intervention.
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It has no specific treatment and carries a poor prognosis, since most patients present with advanced heart failure."
    explanation: States the presentation stage and its prognostic consequence.
phenotypes:
- category: Clinical
  name: Endocardial fibrosis
  description: >
    The defining lesion: dense fibrous thickening of the ventricular endocardium at the apex
    and inflow tract, measurable at millimetre scale.
  phenotype_term:
    preferred_term: Endocardial fibrosis
    term:
      id: HP:0006685
      label: Endocardial fibrosis
    clinical_course: PROGRESSIVE
  frequency: OBLIGATE
  evidence:
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is characterized by fibrotic thickening of the endocardium and myocardium of one or both ventricles."
    explanation: The obligate defining feature.
- category: Clinical
  name: Restrictive cardiomyopathy
  description: >
    Impaired ventricular filling with preserved systolic function, the haemodynamic category
    the disease defines worldwide.
  phenotype_term:
    preferred_term: Restrictive cardiomyopathy
    term:
      id: HP:0001723
      label: Restrictive cardiomyopathy
  frequency: OBLIGATE
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Endomyocardial fibrosis is the most common restrictive cardiomyopathy worldwide."
    explanation: Establishes the phenotype and the disease's standing within that category.
- category: Clinical
  name: Mitral regurgitation
  description: >
    Mechanical regurgitation from tethering of the subvalvular apparatus in left-sided
    disease, characteristically involving the posterior leaflet, and typically severe.
  phenotype_term:
    preferred_term: Mitral regurgitation
    term:
      id: HP:0001653
      label: Mitral regurgitation
  frequency: FREQUENT
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All but one female patient with mild ventricular lesions and no valvular involvement had severe atrioventricular valve regurgitation"
    explanation: Operative series showing near-universal severe atrioventricular regurgitation in patients with more than mild ventricular disease.
- category: Clinical
  name: Tricuspid regurgitation
  description: >
    The right-sided counterpart, from tethering of the tricuspid subvalvular apparatus, and
    the source of the giant venous v waves and the ascites that dominate right-sided
    presentations.
  phenotype_term:
    preferred_term: Tricuspid regurgitation
    term:
      id: HP:0005180
      label: Tricuspid regurgitation
  frequency: FREQUENT
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "had severe atrioventricular valve regurgitation with valves considered suitable for both replacements"
    explanation: Operative documentation of severe atrioventricular regurgitation requiring intervention.
- category: Clinical
  name: Congestive heart failure
  description: >
    The presenting syndrome, usually New York Heart Association class III or IV by the time
    of diagnosis.
  phenotype_term:
    preferred_term: Congestive heart failure
    term:
      id: HP:0001635
      label: Congestive heart failure
    clinical_course: PROGRESSIVE
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All but one patient was in NYHA functional class III or IV at the time of surgery."
    explanation: Quantifies both the presence and the severity of heart failure at presentation.
- category: Symptom
  name: Dyspnea
  description: >
    Exertional breathlessness, dominant in left-sided and biventricular disease.
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  frequency: FREQUENT
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"
    explanation: >-
      Establishes the heart failure syndrome of which dyspnoea is the cardinal symptom.
      Graded INDIRECT because dyspnoea is not itemised separately.
- category: Clinical
  name: Ascites
  description: >
    A hallmark of right-sided disease, and characteristically out of proportion to peripheral
    oedema, which is the physical finding that most reliably suggests the diagnosis in an
    endemic setting.
  phenotype_term:
    preferred_term: Ascites
    term:
      id: HP:0001541
      label: Ascites
  frequency: FREQUENT
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"
    explanation: >-
      Establishes the congestive syndrome that produces ascites in right-sided disease.
      Graded INDIRECT because ascites is not named in the abstract.
- category: Clinical
  name: Hepatomegaly
  description: >
    Congestive hepatomegaly from chronically elevated systemic venous pressure in right-sided
    disease.
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "EMF leads to restrictive physiology, atrioventricular valve dysfunction, and progressive heart failure"
    explanation: >-
      Establishes the congestive physiology behind hepatomegaly. Graded INDIRECT because
      the finding is not named in the abstract.
- category: Clinical
  name: Atrial fibrillation
  description: >
    Arises on a substrate of massive biatrial dilatation and adds its own thromboembolic risk.
  phenotype_term:
    preferred_term: Atrial fibrillation
    term:
      id: HP:0005110
      label: Atrial fibrillation
  frequency: FREQUENT
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."
    explanation: Gives the 30 to 40 percent rate supporting the FREQUENT band, with the source's caveat that the estimate rests on limited regional data.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: >-
      Names arrhythmia among established complications. Graded INDIRECT because the
      specific rhythm is not stated.
- category: Clinical
  name: Thromboembolism
  description: >
    From ventricular mural thrombus or fibrillating atria, and a recognised cause of both
    stroke and pulmonary embolism in this population.
  phenotype_term:
    preferred_term: Thromboembolism
    term:
      id: HP:0001907
      label: Thromboembolism
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."
    explanation: Gives the 15 to 20 percent rate supporting the OCCASIONAL band, which FrequencyEnum defines as 5 to 29 percent, with the source's own caveat that the estimate rests on limited regional data.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: Directly names thromboembolism as an established complication.
- category: Clinical
  name: Abnormal cardiac atrium morphology
  description: >
    Massive biatrial dilatation, disproportionate to the ventricular size, is the
    echocardiographic signature that first raises the diagnosis.
  phenotype_term:
    preferred_term: Abnormal cardiac atrium morphology
    term:
      id: HP:0005120
      label: Abnormal cardiac atrium morphology
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "We designed the study aimed at assessing the cardio-structural abnormalities and coronary vascular changes faced with EMF patients using echocardiography"
    explanation: >-
      Establishes echocardiographic structural assessment as the method by which the
      atrial abnormality is characterised. Graded INDIRECT because atrial dilatation is
      not itemised in the abstract.
- category: Laboratory
  name: Increased total eosinophil count
  description: >
    Variably present, and characteristically absent by the fibrotic stage at which most
    patients in endemic areas are diagnosed. Its absence at diagnosis is one reason the
    eosinophil hypothesis has been so hard to test in tropical endomyocardial fibrosis.
  phenotype_term:
    preferred_term: Increased total eosinophil count
    term:
      id: HP:0001880
      label: Increased total eosinophil count
    temporality: TRANSIENT
  frequency: FREQUENT
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Limited contemporary data report variable eosinophil elevations (30%-50%) without consistent correlation to disease activity"
    explanation: Gives the 30 to 50 percent rate supporting the FREQUENT band, and states the absence of correlation with activity that keeps eosinophilia from being usable as a disease marker.
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome"
    explanation: >-
      Establishes the eosinophilic relationship that motivates measuring the count.
      Graded INDIRECT because the abstract does not state the frequency of eosinophilia
      in tropical endomyocardial fibrosis itself.
- category: Symptom
  name: Orthopnea
  description: >
    Breathlessness on lying flat, part of the left-sided presentation together with
    exertional dyspnoea and paroxysmal nocturnal dyspnoea.
  phenotype_term:
    preferred_term: Orthopnea
    term:
      id: HP:0012764
      label: Orthopnea
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LV EMF typically manifests as exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and an apical pansystolic murmur of mitral regurgitation"
    explanation: Names orthopnoea explicitly among the left-sided manifestations.
- category: Clinical
  name: Sudden cardiac death
  description: >
    Reported in 5 to 10 percent of advanced cases. The source states plainly that this
    estimate comes from limited regional data, which is preserved here rather than dropped,
    because the precision of these numbers is itself part of what is unknown about the
    disease.
  phenotype_term:
    preferred_term: Sudden cardiac death
    term:
      id: HP:0001645
      label: Sudden cardiac death
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Reported event rates suggest thromboembolism in up to 15%-20%, atrial fibrillation in 30%-40%, and sudden cardiac death in 5%-10% of advanced cases, although these estimates are derived from limited regional data."
    explanation: Gives the rate supporting the OCCASIONAL band, with the source's own caveat about the strength of the estimate.
- category: Clinical
  name: Hepatosplenomegaly
  description: >
    Congestive organomegaly in right-sided disease, accompanying the prominent systolic
    jugular pulsation of severe tricuspid regurgitation.
  phenotype_term:
    preferred_term: Hepatosplenomegaly
    term:
      id: HP:0001433
      label: Hepatosplenomegaly
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RV EMF often presents with a loud tricuspid regurgitant murmur, prominent systolic jugular pulsation, and hepatosplenomegaly."
    explanation: Names hepatosplenomegaly among the right-sided findings.
progression:
- phase: Acute necrotic stage
  notes: >
    Davies stage one, lasting up to about five months: eosinophilic infiltration of the
    subendocardium with myocyte necrosis and troponin release. In hypereosinophilic syndrome
    this stage is generally asymptomatic and detectable by troponin and cardiac magnetic
    resonance. In tropical endomyocardial fibrosis it is almost never observed, because
    patients in endemic areas do not reach care until heart failure has developed.
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At the early generally asymptomatic stage, related to subendocardial eosinophilic infiltrates, elevation of the biomarker of cardiac damage (serum troponin) and cardiac MRI are the best tools for diagnosis."
    explanation: Characterises the early stage and the tools that detect it.
- phase: Thrombotic stage
  notes: >
    Davies stage two, beginning around ten months and running over years: mural thrombus
    forms over the damaged endocardium at the apex and beneath the posterior mitral leaflet,
    and is organised rather than lysed.
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "As disease progresses, patients typically develop intracardiac mural thrombi"
    explanation: Places mural thrombus as the intermediate stage of the sequence.
- phase: Fibrotic stage
  notes: >
    Davies stage three: dense acellular endocardial scar, restrictive physiology, and
    atrioventricular regurgitation. This stage is irreversible, and it is where nearly all
    diagnosis happens. One-third to one-half of patients with advanced disease die within two
    years.
  evidence:
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Medical care currently remains very challenging as one-third to half of patients with an advanced disease die within 2 years."
    explanation: Quantifies the prognosis of the fibrotic stage.
- phase: Subclinical detected disease
  notes: >
    Population echocardiographic screening reveals a large reservoir of the disease that
    never reaches clinical attention. In rural Mozambique, only 22.7 percent of screen-detected
    cases were symptomatic, and most had mild-to-moderate structural abnormalities. Whether
    these represent early disease destined to progress, or a stable non-progressive form, is
    unknown and is arguably the most consequential open question about the natural history.
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most affected subjects had mild-to-moderate structural and functional echocardiographic abnormalities. Only 48 persons with endomyocardial fibrosis (22.7%) were symptomatic."
    explanation: Documents the large asymptomatic reservoir revealed by population screening.
diagnosis:
- name: Transthoracic echocardiography
  description: >
    The primary diagnostic tool, and the only practical one in the settings where the disease
    occurs. It shows apical obliteration, endocardial thickening, subvalvular tethering with
    atrioventricular regurgitation, and biatrial dilatation, and it detects asymptomatic
    disease that would otherwise be invisible. Standardised criteria and a severity score
    make it usable for population screening.
  diagnosis_term:
    preferred_term: echocardiography
    term:
      id: NCIT:C16525
      label: Echocardiography Test
  evidence:
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our research has shown that echocardiographic screening using standard criteria adds sensitivity and precision to the diagnosis, particularly in asymptomatic disease, providing an opportunity for longitudinal community-based research."
    explanation: Establishes standardised echocardiographic screening as the method that made asymptomatic disease detectable.
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We used transthoracic echocardiography to determine the prevalence of endomyocardial fibrosis in a rural area of Mozambique."
    explanation: The method used in the population study that defined the disease's true frequency.
- name: Cardiac magnetic resonance imaging
  description: >
    Superior tissue characterisation, able to separate the inflammatory from the fibrotic
    stage and to demonstrate the subendocardial scar and adherent thrombus. Its practical
    relevance in endemic settings is limited by availability, which is itself part of why the
    disease is under-studied.
  diagnosis_term:
    preferred_term: magnetic resonance imaging
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Echocardiography remains the primary diagnostic tool, especially in resource-limited settings, while cardiac MRI offers superior tissue characterization."
    explanation: States the division of labour between the two imaging modalities and the reason for it.
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "New imaging modalities such as strain imaging and specific sequences in MRI offer the perspective of detecting subtle perturbations and distinguishing inflammatory versus fibrotic stages."
    explanation: Documents the specific capability that matters mechanistically, separating the reversible from the irreversible stage.
- name: Endomyocardial biopsy
  description: >
    Occasionally used, chiefly where an eosinophilic cause is suspected but the blood count is
    not informative. Its yield is limited in a characteristic way: by the time fibrosis is
    established the eosinophils have degranulated or been replaced, so a negative biopsy does
    not exclude an eosinophilic origin. That is a mechanistically informative limitation, not
    just a technical one.
  diagnosis_term:
    preferred_term: endomyocardial biopsy
    term:
      id: NCIT:C51674
      label: Endomyocardial Biopsy
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Endomyocardial biopsy may help in difficult settings, namely, when blood eosinophilia is not prominent, but may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"
    explanation: States both the indication and the specific reason the test under-detects the mechanism it is looking for.
treatments:
- name: Endocardial decortication with atrioventricular valve repair or replacement
  description: >
    The only intervention that changes the course of established disease. The fibrous
    endocardial peel is stripped from the ventricle to restore cavity volume and compliance,
    and the tethered atrioventricular valve is repaired or replaced at the same operation.
    Operative risk is high and the procedure is available to almost none of the people who
    need it, which is the defining inequity of this disease rather than a technical
    limitation.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: cardiac surgery
    term:
      id: NCIT:C157806
      label: Cardiac Surgery
  target_mechanisms:
  - target: Dense endocardial fibrous scar
    treatment_effect: BYPASSES
    description: >
      Surgical removal of the fibrous peel physically relieves the restriction the scar
      imposes, without addressing the process that produced it.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Open-heart surgery to detach the endocardial fibrous tissue and repair the atrioventricular valve, remains the last resource to prolong patients' survival."
      explanation: Describes both components of the operation and its status as the only survival-prolonging option.
  evidence:
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Surgery in the correct setting can increase survival and especially in patients with advanced heart failure."
    explanation: States the survival benefit and its conditionality on setting.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Surgical intervention-particularly endocardial decortication and valve repair-remains the definitive treatment for advanced cases, though it carries high operative risk"
    explanation: Names the specific operation and states its risk honestly.
- name: Atrioventricular valve replacement
  description: >
    Where the subvalvular tethering is too extensive for repair, the valve is replaced. In an
    operative series of 55 children, 45 were replaced and nine repaired, and the replaced
    patients were older, which suggests the window for repair closes as the scar advances.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: valve replacement
    term:
      id: NCIT:C168093
      label: Valve Replacement
  target_mechanisms:
  - target: Atrioventricular valve regurgitation
    treatment_effect: BYPASSES
    description: >
      Prosthetic replacement restores valve competence where the tethered native apparatus
      cannot be made to coapt.
    evidence:
    - reference: PMID:32420101
      reference_title: "Endomyocardial fibrosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "45 patients mean age 6.0 (±3.1) and repair nine patients mean age 3.8 (±2.9)"
      explanation: Gives the split between replacement and repair and the age difference between the two groups.
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with valves considered suitable for both replacements"
    explanation: Operative assessment that the tethered valves required prosthetic replacement.
- name: Diuretic therapy
  description: >
    Palliative decongestion for the ascites and oedema of right-sided disease and the
    pulmonary congestion of left-sided disease. It relieves symptoms and does nothing to the
    scar.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: diuretic
      term:
        id: NCIT:C448
        label: Diuretic
  target_mechanisms:
  - target: Congestive heart failure
    treatment_effect: MODULATES
    description: >
      Volume reduction lowers filling pressures and relieves congestion without altering the
      restrictive physiology that causes it.
    evidence:
    - reference: PMID:41399600
      reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."
      explanation: States the palliative role of diuretics explicitly, with no claim of disease modification.
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It has no specific treatment and carries a poor prognosis"
    explanation: The absence of disease-specific therapy is why management is symptomatic.
- name: Anticoagulation
  description: >
    Directed at the intracardiac thrombus and the atrial fibrillation, both of which are
    intrinsic to the disease rather than incidental. Like diuresis, it is palliative.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: anticoagulant
      term:
        id: NCIT:C263
        label: Anticoagulant Agent
  target_mechanisms:
  - target: Systemic and pulmonary thromboembolism
    treatment_effect: INHIBITS
    description: >
      Anticoagulation reduces propagation and embolisation of intracardiac thrombus.
    evidence:
    - reference: PMID:41399600
      reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."
      explanation: Names anticoagulation among the palliative measures.
  evidence:
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: The thromboembolic complication anticoagulation is directed at.
- name: Antiarrhythmic therapy
  description: >
    Rate or rhythm control for the atrial fibrillation that arises on the dilated-atrium
    substrate. Palliative, and in practice often combined with anticoagulation for the same
    rhythm.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: antiarrhythmic agent
      term:
        id: NCIT:C47793
        label: Antiarrhythmic Agent
  target_mechanisms:
  - target: Atrial dilatation and atrial fibrillation
    treatment_effect: MODULATES
    description: >
      Antiarrhythmic drugs address the rhythm disturbance without affecting the atrial
      dilatation that generates it.
    evidence:
    - reference: PMID:41399600
      reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Treatment is largely symptomatic, with diuretics, anticoagulants, and antiarrhythmics offering palliative benefit."
      explanation: Names antiarrhythmic therapy among the palliative measures.
  evidence:
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "complications such as chronic heart failure, thromboembolism and arrhythmia are already present"
    explanation: >-
      The arrhythmia this treatment addresses. Graded INDIRECT because the source names
      the complication rather than its management.
- name: Prednisolone for recurrent ascites
  description: >
    The only randomised trial of a disease-directed medical therapy in this disease, and it
    was negative. Thirty-five Ugandan patients with grade 2 ascites were randomised to
    prednisolone 1 mg/kg/day or placebo for up to eight weeks; the drug was safe but did not
    significantly reduce progression to grade 3 ascites, with a relative risk of 0.70 and a
    confidence interval crossing one. It is curated here precisely because it is negative:
    the rationale was the peritoneal inflammation thought to drive the ascites, and the
    result is the single most relevant piece of evidence against reaching for
    immunosuppression on the strength of the autoimmune findings elsewhere in this entry.
    A pilot of 35 with six lost to follow-up cannot exclude a modest benefit, so this is a
    failure to demonstrate efficacy rather than a demonstration of futility.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: prednisolone
      term:
        id: NCIT:C769
        label: Prednisolone
  target_mechanisms:
  - target: Sustained eosinophilia and Th2-skewed immune activation
    treatment_effect: INHIBITS
    description: >
      Corticosteroid suppression of the inflammatory arm was the trial rationale, on the
      view that peritoneal and endomyocardial inflammation drive the ascites.
    evidence:
    - reference: PMID:26666319
      reference_title: "The safety and efficacy of prednisolone in preventing reaccumulation of ascites among endomyocardial fibrosis patients in Uganda: a randomized clinical trial."
      supports: REFUTE
      evidence_source: HUMAN_CLINICAL
      snippet: "There was no statistically significant difference in the overall risk of developing grade 3 ascites over 8 weeks."
      explanation: The primary endpoint failed, which refutes the proposition that suppressing inflammation with a corticosteroid controls the ascites over this horizon.
  evidence:
  - reference: PMID:26666319
    reference_title: "The safety and efficacy of prednisolone in preventing reaccumulation of ascites among endomyocardial fibrosis patients in Uganda: a randomized clinical trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prednisolone was safely administered in this setting."
    explanation: The safety finding, which is the trial's positive result and the reason a larger study remains feasible.
  - reference: PMID:26666319
    reference_title: "The safety and efficacy of prednisolone in preventing reaccumulation of ascites among endomyocardial fibrosis patients in Uganda: a randomized clinical trial."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "Inflammation in other parts of the body such as the peritoneum has been described and may explain the accumulation of ascites, a painful and disabling feature of this disease."
    explanation: >-
      States the mechanistic rationale for the trial, and incidentally supports the
      entry's characterisation of the ascites as exudative rather than purely
      congestive. Graded INDIRECT because it is a rationale rather than a result.
  - reference: PMID:26666319
    reference_title: "The safety and efficacy of prednisolone in preventing reaccumulation of ascites among endomyocardial fibrosis patients in Uganda: a randomized clinical trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sixteen study participants were randomised to prednisolone, while nineteen were randomised to placebo. Six were lost to follow up"
    explanation: >-
      The sample size and attrition that bound how much the negative result can be read
      to exclude. It bounds how much the negative result can be read to exclude rather
      than measuring efficacy itself.
genetic:
- name: HLA-B
  gene_term:
    preferred_term: HLA-B
    term:
      id: hgnc:4932
      label: HLA-B
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >
    HLA-B*58 occurred more frequently in Mozambican patients with endomyocardial fibrosis
    than in ethnically matched controls. This is one of only two loci from the only formal
    genetic study of the disease, in 71 patients and 137 controls, and it has not been
    replicated or followed by a genome-wide study. It is curated as susceptibility rather
    than causation, consistent with the model in which genotype determines who among the
    exposed develops fibrosis.
  evidence:
  - reference: PMID:25780800
    reference_title: "Genetic susceptibility to endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with EMF patients being more likely than controls to have the HLA-B*58 allele in Mozambique (p-0.03)"
    explanation: The reported association with its p value, in the study that is the sole formal genetic investigation of this disease.
- name: HLA-A
  gene_term:
    preferred_term: HLA-A
    term:
      id: hgnc:4931
      label: HLA-A
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >
    HLA-A*02:02 occurred more frequently in Ugandan patients than in matched controls. That
    the two populations in the same study yielded different associated alleles is itself
    informative: it is compatible with population-specific alleles tagging a shared
    immune-response mechanism, and equally compatible with two underpowered false positives.
    No replication exists.
  evidence:
  - reference: PMID:25780800
    reference_title: "Genetic susceptibility to endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the HLA-A*02:02 in Uganda (p = 0.005)"
    explanation: The second reported association, in the Ugandan arm of the same two-centre study.
biochemical:
- name: Circulating anti-myocardial IgG
  presence: INCREASED
  notes: >
    Present in 53.6 percent of endomyocardial fibrosis patients versus 10 percent of healthy
    controls, with the strongest reactivity against myocardial proteins of 35, 42, and 70
    kilodaltons. Reactivity correlates with disease activity, which is what makes it a
    candidate activity marker as well as a candidate mechanism. Whether it identifies
    patients who would benefit from immunosuppression is untested.
  evidence:
  - reference: PMID:20422043
    reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "EMF patients showed greater frequency and reactivity of IgG antibodies against myocardial proteins of molecular weights 35 kD, 42 kD and 70 kD"
    explanation: Identifies the specific antigenic targets and the direction of the difference from controls.
- name: Plasma interleukin-4
  presence: INCREASED
  notes: >
    Significantly higher than in healthy controls in 27 late-stage patients. IL-4 is the
    canonical Th2 cytokine and is the specific measurement behind this entry's Th2
    characterisation of the immune arm.
  evidence:
  - reference: PMID:25303100
    reference_title: "Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "plasma levels of IL-10, IL-4, and TNF-α were significantly higher than those of controls"
    explanation: The case-control comparison establishing the elevation.
- name: Plasma interleukin-10
  presence: INCREASED
  notes: >
    Elevated alongside IL-4. The authors read IL-10 and IL-4 as possibly homeostatic, raised
    to buffer the pro-inflammatory arm rather than driving injury, which is a caution against
    treating this profile as straightforwardly pathogenic.
  evidence:
  - reference: PMID:25303100
    reference_title: "Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "IL-4 and IL-10 may have been upregulated as a homeostatic mechanism to buffer both production and deleterious cardiovascular effects of pro-inflammatory cytokines"
    explanation: The authors' alternative reading of their own finding, recorded so the cytokine profile is not over-interpreted as causal.
- name: Plasma tumour necrosis factor alpha
  presence: INCREASED
  notes: >
    Elevated, but the authors caution that it may be secondary to the cardiovascular
    involvement rather than a driver of it, which is the same cause-or-consequence problem
    that the autoantibody finding raises.
  evidence:
  - reference: PMID:25303100
    reference_title: "Plasma cytokine profile in tropical endomyocardial fibrosis: predominance of TNF-a, IL-4 and IL-10."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the detection of increased levels of TNF-α may be secondary to the cardiovascular involvement observed in these patients"
    explanation: >-
      Records the elevation together with the authors' own hedge about its direction,
      which is why no directional claim is made here.
classifications:
  harrisons_chapter:
  - classification_value: CARDIOVASCULAR
    notes: >-
      Endomyocardial fibrosis is a restrictive cardiomyopathy and sits in the
      cardiovascular chapter. Its etiology is environmental and nutritional rather than
      primarily cardiac, but the disease entity itself is a cardiomyopathy.
environmental:
- name: Cassava-based diet with severe protein deprivation
  description: >
    The best-evidenced environmental hypothesis, and the only one with a controlled
    experimental test behind it. Populations in endemic areas subsist on cassava with
    little animal protein, and feeding uncooked cassava to African green monkeys under
    protein restriction reproduces the endomyocardial lesion while a banana diet lacking
    the same protein does not. That control is what makes this more than a poverty
    correlation: it separates the cassava from the protein deficiency that accompanies it.
  influences_mechanisms:
  - target: Chronic antigenic or toxic stimulus in a susceptible host
    environmental_effect: PREDISPOSES
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Prolonged cassava ingestion under protein deprivation is the exposure proposed to
      supply the chronic toxic stimulus that initiates endomyocardial injury.
    evidence:
    - reference: PMID:8756020
      reference_title: "Effect of protein deficient cassava diet on Cercopithecus aethiops hearts and its possible role in the aetiology and pathogenesis of endomyocardial fibrosis in man."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Changes in the endomyocardium included cell vacuolation, interstitial fibrosis and endocardial thickening by the 130th day in the animals on cassava but the animals on bananas were free from such changes."
      explanation: The controlled feeding experiment that converts the cassava hypothesis from an epidemiological correlation into an exposure with a demonstrated cardiac effect.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Investigations into nutritional factors in EMF have focused on a possible connection with cassava toxicity."
    explanation: Identifies cassava toxicity as the focus of nutritional investigation in this disease.
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "that cerium-mediated cassava toxicity in the setting of protein deficiency may play a role in the pathogenesis of EMF"
    explanation: >-
      States the combined cerium-plus-cassava-plus-protein-deficiency proposal. It is
      offered as a possibility rather than an established mechanism.
- name: Geochemical exposure to cerium and thorium in monazite soils
  description: >
    A regional hypothesis raised to explain the coastal Kerala focus, where endomyocardial
    fibrosis is prevalent in a zone free of filariasis. It is curated because it is a real
    and recurring proposal in this literature and because its status is unusually clear:
    the systematic review states plainly that no empirical study supports it. Recording an
    unsupported hypothesis with its refuting note is more useful than omitting it, since
    otherwise the same idea reappears as a lead.
  influences_mechanisms:
  - target: Chronic antigenic or toxic stimulus in a susceptible host
    environmental_effect: PREDISPOSES
    causal_link_type: UNKNOWN
    description: >
      Soil-derived rare-earth exposure is proposed as the localised toxic stimulus behind
      regional variation in prevalence.
    evidence:
    - reference: PMID:18301727
      reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Valiathan and Kartha have speculated that cerium or thorium present in monazite deposits may explain regional variation in EMF prevalence in this region"
      explanation: >-
        States the proposed exposure and the geographic observation it was raised to
        explain. It is explicitly labelled speculation.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: NO_EVIDENCE
    evidence_source: HUMAN_CLINICAL
    snippet: "No empirical studies have yet come forward to support this theory."
    explanation: The systematic review's own verdict on the geochemical hypothesis, recorded here so the hypothesis is not mistaken for an established exposure.
  notes: >
    No ECTO term is bound. A search of the ECTO exposure hierarchy returned no term for
    cerium, thorium, monazite, or rare-earth exposure, and binding a broader term such as
    exposure to soil would assert less than the claim requires while looking more precise
    than the evidence is.
- name: Poverty, subsistence farming, and going barefoot
  description: >
    A case-control study from Uganda associated the disease with markers of poverty rather
    than with any single agent. This is curated as an exposure in its own right because it
    is the most robust epidemiological signal in the disease and because the mechanism is
    genuinely unresolved: poverty could act through diet, through helminth exposure from
    going unshod, through reduced access to care, or through all three, and the studies to
    date cannot separate them.
  influences_mechanisms:
  - target: Chronic antigenic or toxic stimulus in a susceptible host
    environmental_effect: PREDISPOSES
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Socioeconomic deprivation is the setting in which the nutritional and infectious
      exposures co-occur, and is itself the most consistently reported association.
    evidence:
    - reference: PMID:32420110
      reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Dietary, environmental and infectious factors seem to combine in susceptible individuals to give rise to an inflammatory process that leads to endomyocardial damage and scar formation."
      explanation: States the combined-exposure model that this entry represents, with the co-occurrence that makes the individual factors hard to separate.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Current evidence supports a multifactorial model in which nutritional deficiencies, infections with associated eosinophilia, immune dysregulation, and genetic predisposition interact within adverse socioeconomic settings to promote progressive endocardial fibrosis"
    explanation: Places socioeconomic setting as the context within which the other exposures act, which is why it is modelled as an exposure rather than as a confounder.
- name: Chronic helminth and malarial infection
  description: >
    Schistosomiasis and filariasis are common in endemic zones and are the classical
    proposed source of the eosinophilia. The evidence undercuts a simple version of the
    hypothesis in a specific way worth preserving: parasite load does not consistently
    differ between cases and controls, which is what turns eosinophilia from a universal
    initiator into an amplifier acting on some other primary insult.
  influences_mechanisms:
  - target: Sustained eosinophilia and Th2-skewed immune activation
    environmental_effect: PREDISPOSES
    causal_link_type: DIRECT
    description: >
      Chronic helminth infection is the proposed driver of the sustained eosinophilia on
      which the accepted mechanism depends.
    evidence:
    - reference: PMID:41399600
      reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Parasitic infections-particularly schistosomiasis and filariasis-are common cofactors in endemic zones"
      explanation: >-
        Names the specific parasites proposed as cofactors. Cofactor status is weaker
        than the causal role the eosinophil model would need.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "parasitic load does not consistently differ between EMF and control subjects"
    explanation: Refutes a straightforward parasite-burden model of causation, and is the observation behind treating eosinophilia as an amplifier rather than an initiator.
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "While the prevalence of plasmodial species does not match the geographic distribution of EMF, these findings point to changes in immunity as a possible pathway from malaria to endocardial disease."
    explanation: States both the geographic mismatch that argues against malaria as a cause and the immune-alteration pathway that keeps it in contention.
experimental_models:
- name: Cassava-fed Cercopithecus aethiops with protein deprivation
  description: >
    The only animal model that reproduces the human lesion from a proposed natural exposure
    rather than from a laboratory insult. Three African green monkeys were fed uncooked
    cassava and three uncooked banana, and hearts were taken for histology as health
    deteriorated. Cassava-fed animals developed endocardial thickening, interstitial
    fibrosis, papillary muscle fibrosis, and apical left ventricular fibrosis; banana-fed
    animals did not. The banana arm is the crucial control, because it was also
    protein-free, which separates a cassava-specific effect from generic protein
    deprivation. Limitations are real: n is three per arm, the endpoint is histology in a
    deteriorating animal rather than a defined disease state, and no eosinophilic phase was
    described, so the model supports the nutritional arm without addressing the eosinophil
    arm at all.
  experimental_model_type: OTHER
  organism:
    preferred_term: Chlorocebus aethiops
    term:
      id: NCBITaxon:9534
      label: Chlorocebus aethiops
  modeled_mechanisms:
  - target: Chronic antigenic or toxic stimulus in a susceptible host
    description: >
      The model instantiates the proposed dietary toxic exposure directly.
  - target: Dense endocardial fibrous scar
    description: >
      The model reproduces the defining endocardial lesion, including its apical and
      papillary distribution.
  publication: PMID:8756020
  evidence:
  - reference: PMID:8756020
    reference_title: "Effect of protein deficient cassava diet on Cercopithecus aethiops hearts and its possible role in the aetiology and pathogenesis of endomyocardial fibrosis in man."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "By the 160th day, the former exhibited marked thickening of the endocardium, interstitial fibrosis, fibrous septa formation, pappillary muscle fibrosis as well as apical fibrosis of the left ventricle, which findings occur in the human disease."
    explanation: Documents recapitulation of the specific human lesion, including its apical and papillary distribution.
  - reference: PMID:8756020
    reference_title: "Effect of protein deficient cassava diet on Cercopithecus aethiops hearts and its possible role in the aetiology and pathogenesis of endomyocardial fibrosis in man."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "the animals on bananas, which also lacked protein did not develop similar changes"
    explanation: The control that distinguishes a cassava-specific effect from protein deprivation alone, and the single most informative result in the model.
- name: Plantain and serotonin dietary models
  description: >
    A refuted hypothesis, retained because the refutation is the useful part. High urinary
    5-hydroxyindole-acetic acid in West and East Africans suggested that serotonin from a
    plantain-based diet caused the disease. Plantains were fed to guinea pigs, rats, and
    Patas monkeys, and typical lesions did not appear; serum 5-hydroxytryptamine failed to
    rise in patients fed plantains in Nigeria; and the line of inquiry stopped. Curating
    this prevents the hypothesis being rediscovered as a lead, and it shows that this
    disease's model literature contains genuine negative results rather than only
    untested proposals.
  experimental_model_type: OTHER
  modeled_mechanisms:
  - target: Chronic antigenic or toxic stimulus in a susceptible host
    description: >
      The models tested a dietary serotonin exposure as the proposed toxic stimulus, and
      failed to reproduce the disease.
  publication: PMID:18301727
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: "They could not reproduce typical EMF lesions."
    explanation: The negative result in guinea pigs, rats, and Patas monkeys that ended the serotonin hypothesis.
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "Early enthusiasm for the role of serotonin in a plantain-based diet waned by the early 1970s"
    explanation: Records the abandonment of the hypothesis, which together with the animal negative is why this model is curated as a refutation.
- name: Fibroblast and cardiomyocyte coculture
  description: >
    The only cell-based system used for this disease, and explicitly not a disease model.
    Cocultures of RT3 fibroblasts with SV40-transformed RL-14 cardiomyocytes show fibroblast
    migration, vimentin upregulation, inhibition of cardiomyocyte proliferation, and
    distortion of cardiomyocyte morphology. The published limitations are unusually candid
    and are reproduced here because they matter for how the results should be read: the cell
    lines are artificial, there are no eosinophils and no endothelial cells in the system,
    and the extracellular matrix is not physiologic. Since eosinophils and endocardial
    endothelium are precisely the cells the accepted mechanism turns on, this system cannot
    speak to the initiating injury at all.
  experimental_model_type: CO_CULTURE
  modeled_mechanisms:
  - target: Fibroblast activation and excessive collagen deposition
    description: >
      The coculture models the fibroblast-cardiomyocyte interaction of the fibrogenic step
      only, downstream of the injury it cannot represent.
  publication: PMID:41399600
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    snippet: "demonstrating fibroblast migration, vimentin upregulation, inhibition of cardiomyocyte proliferation, and morphologic distortion of cardiomyocytes"
    explanation: >-
      The findings the system produces. Graded INDIRECT because they are mechanistic
      proxies rather than disease recapitulation.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: REFUTE
    evidence_source: IN_VITRO
    snippet: "However, these models serve only as mechanistic proxies rather than true EMF disease models."
    explanation: The authors' explicit statement that this is not a disease model, recorded so the coculture results are not read as evidence about the disease itself.
histopathology:
- name: Dense endocardial fibrous thickening with apical and valvular extension
  description: >
    The defining pathological appearance: fibrous thickening running from the ventricular
    apices onto the posterior mitral or tricuspid leaflets, characteristically sparing the
    outflow tracts. That sparing is diagnostically useful, because it distinguishes the
    distribution from diseases that involve the whole ventricle.
  diagnostic: true
  notes: >
    No finding_term is bound. HistopathologyFindingTerm is restricted to the NCIT
    histopathology-result branch, and that branch contains no endocardial or cardiac
    fibrosis morphologic term. HP:0006685 Endocardial fibrosis exists and is used on the
    corresponding phenotype in this entry, but it is not a member of this enum, and NCIT's
    Endomyocardial Fibrosis term is a disease concept rather than a morphologic finding.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pathologically, EMF is characterized by fibrotic thickening of the endocardium extending from the apices to the posterior mitral or tricuspid leaflets, typically sparing the outflow tracts."
    explanation: The defining pathological distribution, including the outflow-tract sparing that discriminates it.
- name: Mural thrombus, dystrophic calcification, and subendocardial neovascularisation
  description: >
    The accompanying features of the established lesion. Subendocardial neovascularisation
    is the least expected of these in what is otherwise an acellular scar, and mural
    thrombus is the histological trace of the intermediate stage of the disease.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Common features include mural thrombi, dystrophic calcification, papillary muscle and chordal fibrosis, and subendocardial neovascularization."
    explanation: Enumerates the associated findings, including the chordal fibrosis that produces the valve regurgitation.
- name: Stage-dependent microscopic appearance
  description: >
    Microscopy differs by stage rather than by side. Acute lesions show eosinophilic
    infiltration and necrosis; chronic lesions show dense collagen, elastic fibre
    fragmentation, and endocardial thickening. This is the histological form of the
    entry's central evidential problem, since the eosinophilic appearance is only visible
    in a stage that is almost never biopsied in endemic settings.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "acute lesions show eosinophilic infiltration and necrosis, while chronic lesions exhibit dense collagen, elastic fiber fragmentation, and endocardial thickening"
    explanation: The stage-dependent microscopic findings that underpin the Davies staging used in this entry's progression section.
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Left- and right-sided lesions demonstrate similar histology but differ in distribution."
    explanation: Establishes that laterality changes the distribution and not the tissue lesion, which is why this entry curates one histological process across both ventricles.
- name: Endocardial thickness at surgery
  description: >
    Measured at a mean of three millimetres in an operative series of 55 children, with a
    maximum above five and a half millimetres. The scale is what makes surgical
    decortication feasible: this is a peel that can be found and lifted, not a diffuse
    infiltration.
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mean endocardial thickness was 3,000 (±1519) µm."
    explanation: Direct operative measurement quantifying the lesion.
prevalence:
- population: Rural Mozambique, all ages, echocardiographic population screen
  measure_type: POINT_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 19800.0
  notes: >
    An estimated 19.8 percent of a random cluster sample of 1063 subjects had
    echocardiographic endomyocardial fibrosis, with a peak of 28.1 percent in the 10 to 19
    year age group. This is the figure that reframed the disease from a rare referral
    diagnosis to a major endemic public-health problem, and it is a screen-detected
    prevalence rather than a clinical one.
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The estimated overall prevalence of endomyocardial fibrosis was 19.8%, or 211 of 1063 subjects"
    explanation: The primary prevalence estimate from the only population-based study.
- population: Kampala, Uganda, patients referred for echocardiography
  measure_type: POINT_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  notes: >
    The disease accounts for 20 percent of heart disease patients referred for
    echocardiography in Kampala. This is a referral-population figure, not a population
    prevalence, and is recorded to document the clinical burden in endemic centres.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In Kampala, the disease accounts for 20% of heart disease patients referred for echocardiography."
    explanation: Quantifies the referral burden in a historically endemic centre.
differential_diagnoses:
- name: Constrictive pericarditis
  description: >
    The classic mimic, since both produce restrictive filling with preserved systolic
    function and prominent right-sided congestion. Imaging separates them by locating the
    lesion: a thickened, adherent pericardium in constriction versus a thickened endocardium
    with an obliterated apex and tethered subvalvular apparatus in endomyocardial fibrosis.
    The distinction matters because pericardiectomy and endocardial decortication are
    different operations.
  evidence:
  - reference: PMID:41399600
    reference_title: "A Narrative Review on Endomyocardial Fibrosis: Unraveling an Under-Recognized Tropical Heart Disease."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diagnosis is often delayed due to overlap with other causes of heart failure and limited access to advanced imaging."
    explanation: >-
      States the diagnostic-overlap problem this differential belongs to. Graded
      INDIRECT because constrictive pericarditis is not named specifically.
- name: Hypereosinophilic syndrome with cardiac involvement
  description: >
    Löffler endocarditis produces an endocardial lesion that is histologically and
    echocardiographically indistinguishable from tropical endomyocardial fibrosis at the
    fibrotic stage. The separation is by context, not by cardiac appearance: a documented
    marked eosinophilia, often with an identifiable clonal or reactive cause, versus an
    endemic tropical setting with no eosinophilia at presentation. This is more than a
    differential, since it is the disease from which the mechanism of endomyocardial fibrosis
    is inferred.
  evidence:
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "its pathology resembles conditions such as eosinophilic cardiomyopathy and hypereosinophilic syndrome"
    explanation: States the pathologic indistinguishability that makes this simultaneously a differential and a mechanistic model.
- name: Rheumatic mitral valve disease
  description: >
    Also common in the same populations and also presents with severe mitral regurgitation
    in a young patient. The discriminating feature is the ventricle rather than the valve:
    rheumatic disease damages the leaflets and commissures with a normal ventricular apex,
    whereas endomyocardial fibrosis leaves the leaflets structurally intact and tethers them
    from an obliterated, scarred apex.
  evidence:
  - reference: PMID:32420101
    reference_title: "Endomyocardial fibrosis."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "The echocardiographic changes corresponded well to the findings on surgery and histopathology."
    explanation: >-
      Supports echocardiography's ability to characterise the ventricular lesion that
      distinguishes the two. Graded INDIRECT because rheumatic disease is not the
      comparator in this study.
clinical_burden:
  burden_level: HIGH
  rationale: >
    A progressive, incurable cardiomyopathy of children and young adults, presenting in New
    York Heart Association class III or IV in nearly all diagnosed cases, with one-third to
    one-half of advanced patients dead within two years. There is no disease-specific drug.
    The only intervention that prolongs survival is open-heart surgery, which carries high
    operative risk and is unavailable to the overwhelming majority of affected people, who
    live in rural low-income settings.
  notes: >
    The burden is inseparable from the setting. Population screening in rural Mozambique
    found nearly one in five people affected, with a peak in adolescence, which makes this
    a major endemic cause of heart failure in the affected regions rather than a rare
    disease in the usual sense. Late diagnosis is driven by lack of clinical awareness and
    poor access to care, so the complications of heart failure, thromboembolism, and
    arrhythmia are typically already present when the disease is first recognised.
  evidence:
  - reference: PMID:31414216
    reference_title: "Endomyocardial fibrosis: past, present, and future."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Medical care currently remains very challenging as one-third to half of patients with an advanced disease die within 2 years."
    explanation: Quantifies mortality in advanced disease.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Lack of awareness by health professionals and low access to health care determine late diagnosis, when complications such as chronic heart failure, thromboembolism and arrhythmia are already present."
    explanation: Identifies the access and awareness failures that determine when the disease is caught.
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It has no specific treatment and carries a poor prognosis, since most patients present with advanced heart failure."
    explanation: States the absence of specific therapy and the presentation stage together.
discussions:
- discussion_id: eosinophil_hypothesis_untestable_in_endemic_setting
  prompt: >
    Is tropical endomyocardial fibrosis actually caused by eosinophil-mediated endocardial
    injury, or has that mechanism been imported wholesale from hypereosinophilic syndrome on
    the strength of a shared end-stage lesion?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Sustained eosinophilia and Th2-skewed immune activation
  - pathophysiology#Eosinophil degranulation and endocardial injury
  rationale: >
    The eosinophil model is coherent and is directly evidenced in hypereosinophilic syndrome,
    where the acute infiltrative stage, the thrombotic stage, and the fibrotic stage are all
    observed prospectively in the same patients. In tropical endomyocardial fibrosis, none of
    that is observed. Patients present at the fibrotic stage, eosinophilia is usually absent
    by then, and biopsy at that point is uninformative in a specific and vicious way, because
    degranulation and replacement by fibrosis erase the evidence of the very process being
    looked for. The inference therefore runs backwards from a shared end-stage appearance,
    which is exactly the reasoning pattern that would also be satisfied if two different
    upstream processes converged on one scar. The alternative worth taking seriously is that
    the endemic disease is driven by something else entirely, with the eosinophilic
    endocarditis of hypereosinophilic syndrome being a separate route to the same
    architecture. Population screening now makes the decisive study possible for the first
    time, because it identifies affected people before the fibrotic stage.
  proposed_experiments:
  - experiment_id: exp_emf_prospective_early_stage_cohort
    name: Longitudinal follow-up of screen-detected early endomyocardial fibrosis with serial eosinophil and cardiac biomarker measurement
    description: >-
      Enrol screen-detected asymptomatic and mild cases from an endemic population, and follow
      them with serial eosinophil counts, troponin, cardiac magnetic resonance tissue
      characterisation, and echocardiographic severity scoring, comparing those who progress
      against those who do not.
    decision_criterion: >-
      Eosinophilia or a troponin and magnetic resonance signature of active eosinophilic
      inflammation preceding progression would establish the eosinophil route in the endemic
      disease; progression without any such signal would show that the mechanism inferred from
      hypereosinophilic syndrome does not transfer.
  evidence:
  - reference: PMID:34172539
    reference_title: "Hypereosinophilic syndrome: considerations for the cardiologist."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "may be non-contributive due to sampling issues or eosinophil degranulation or replacement by fibrosis"
    explanation: Documents precisely why the mechanism cannot be confirmed at the stage at which the endemic disease is diagnosed.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "efforts to understand its mechanisms and natural history have been hampered by the incapacity to detect the early stages of the disease in endemic areas"
    explanation: States the structural reason the mechanism is unresolved, and by implication what would resolve it.
- discussion_id: geographic_distribution_unexplained
  prompt: >
    Why is endomyocardial fibrosis confined to specific equatorial regions, when the exposures
    proposed to cause it are not?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Chronic antigenic or toxic stimulus in a susceptible host
  rationale: >
    This is the constraint every etiologic hypothesis has failed. Filariasis and
    schistosomiasis are widespread far beyond the endemic zone; cassava is eaten across the
    tropics; malaria's distribution does not match the disease's. A systematic review across
    six decades concluded that no proposed account explains the geography. Three structurally
    different explanations remain open. The cause may be a genuinely localised exposure not
    yet identified, such as a soil geochemical factor, in which case the geography is the
    signal rather than the puzzle. It may require a specific conjunction of exposures that
    happens to co-occur only in those regions, in which case single-factor studies were
    always going to fail. Or the apparent geography may be substantially an artefact of where
    anyone has looked, which population screening in non-endemic tropical regions could test
    directly and cheaply.
  proposed_experiments:
  - experiment_id: exp_emf_geographic_screening_survey
    name: Standardised echocardiographic prevalence survey across matched endemic and non-endemic tropical regions
    description: >-
      Apply the same standardised echocardiographic criteria and severity score used in the
      Mozambique population study to random population samples in tropical regions with
      comparable helminth burden, diet, and poverty but no reported endomyocardial fibrosis,
      alongside a contemporaneous endemic-region sample as a positive control.
    decision_criterion: >-
      Comparable prevalence in supposedly non-endemic regions would show the geography is
      largely an ascertainment artefact and would redirect etiologic search away from
      localised exposures; a genuinely sharp geographic boundary under identical
      ascertainment would make a localised environmental factor the leading hypothesis and
      would define where to look for it.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Despite several hypotheses regarding cause, no account of the etiology of this disease has yet fully explained its unique geographical distribution."
    explanation: The systematic review's conclusion, which is the premise of this gap.
- discussion_id: screen_detected_disease_natural_history
  prompt: >
    Do the mild, asymptomatic cases found by population echocardiographic screening progress
    to clinical endomyocardial fibrosis, or are they a largely stable finding?
  kind: OPEN_QUESTION
  status: OPEN
  attaches_to:
  - pathophysiology#Dense endocardial fibrous scar
  - pathophysiology#Restrictive diastolic physiology
  rationale: >
    Screening a rural Mozambican population found echocardiographic disease in nearly a fifth
    of people, but only 22.7 percent of those were symptomatic and most had only
    mild-to-moderate abnormalities. Two readings have opposite consequences. If most
    screen-detected cases progress, then the clinical disease is the visible fraction of a
    very large iceberg, screening would identify a huge population for early intervention,
    and the prevalence figure is a public-health emergency. If most are stable, then the
    screening criteria are detecting a common structural variant or a self-limited healed
    lesion, and treating the prevalence as a burden estimate overstates it substantially. No
    longitudinal follow-up of a screen-detected cohort has been published, so the question is
    open on the evidence rather than merely contested.
  proposed_experiments:
  - experiment_id: exp_emf_screen_detected_longitudinal_followup
    name: Ten-year longitudinal follow-up of an echocardiographically screen-detected endomyocardial fibrosis cohort
    description: >-
      Re-examine the screen-detected cohort at fixed intervals with the same standardised
      criteria and severity score, recording progression in severity grade, onset of symptoms,
      incident complications, and mortality, against screen-negative controls from the same
      sampling frame.
    decision_criterion: >-
      Substantial progression in severity grade or symptom onset in a majority of
      screen-detected mild cases would establish them as early disease and justify screening
      programmes; stability across a decade would require the screening criteria to be
      recalibrated and the prevalence figure reinterpreted.
  evidence:
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Most affected subjects had mild-to-moderate structural and functional echocardiographic abnormalities. Only 48 persons with endomyocardial fibrosis (22.7%) were symptomatic."
    explanation: The observation that creates the question, with the numbers that make its resolution consequential.
  - reference: PMID:18596273
    reference_title: "A population study of endomyocardial fibrosis in a rural area of Mozambique."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "By using echocardiography, we were able to detect early, asymptomatic stages of the disease."
    explanation: The authors' own interpretation, that these are early stages, which is the reading the proposed follow-up would test.
- discussion_id: autoimmunity_cause_or_consequence
  prompt: >
    Do circulating anti-myocardial antibodies sustain injury in endomyocardial fibrosis, or
    merely mark injury that has already occurred?
  kind: OPEN_QUESTION
  status: OPEN
  attaches_to:
  - pathophysiology#Anti-myocardial autoantibody response
  rationale: >
    Anti-myocardial IgG is present in about half of patients and a tenth of controls, and its
    intensity correlates with disease activity. Correlation with activity is compatible with
    both readings, since an antibody that drives injury and an antibody that reports injury
    would both track it. The authors of the only study explicitly declined to resolve it. The
    stakes are concrete rather than academic: only the causal reading would justify trialling
    immunosuppression in a disease that currently has no medical therapy at all, and giving
    immunosuppression on the strength of a marker would expose a malnourished, often
    parasitised population to real harm. That trial has in fact been attempted once. A pilot
    randomised trial of prednisolone in 35 Ugandan patients found the drug safe but failed to
    show a reduction in ascites reaccumulation, with a relative risk of 0.70 and a confidence
    interval crossing one. It targeted the ascites rather than the autoantibody arm, and with
    16 patients on active drug and six lost to follow-up it cannot exclude a modest effect, so
    it does not settle this question. It does mean the question is no longer purely
    hypothetical, and that any future immunosuppression proposal has to say what it would do
    differently.
  proposed_experiments:
  - experiment_id: exp_emf_autoantibody_temporal_sequence
    name: Serial autoantibody measurement in a screen-detected cohort followed to progression
    description: >-
      Measure anti-myocardial IgG serially in screen-detected early cases, and determine
      whether antibody appearance and titre rise precede or follow echocardiographic
      progression in individual patients.
    decision_criterion: >-
      Antibody appearance preceding progression within individuals would support a causal or
      perpetuating role and would justify a pilot immunosuppression trial; antibody rise
      following progression would establish it as a marker and rule out that trial.
  evidence:
  - reference: PMID:20422043
    reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF, therefore improving its management by identifying patients who may benefit from immunosuppressive therapy."
    explanation: States the activity correlation and the therapeutic hope that rests on the causal reading.
  - reference: PMID:20422043
    reference_title: "Presence of circulating anti-myosin antibodies in endomyocardial fibrosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "it is unclear whether the primary target of injury is the endocardial endothelium, the subendocardial fibroblast, the coronary microcirculation or the myocyte"
    explanation: The authors' framing of the unresolved question about what is being injured, which this discussion extends to what is doing the injuring.
  - reference: PMID:26666319
    reference_title: "The safety and efficacy of prednisolone in preventing reaccumulation of ascites among endomyocardial fibrosis patients in Uganda: a randomized clinical trial."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "There was no statistically significant difference in the overall risk of developing grade 3 ascites over 8 weeks."
    explanation: The one attempt at immunosuppression in this disease, and it was negative on its primary endpoint, which constrains the therapeutic argument this discussion turns on.
- discussion_id: research_neglect_as_a_disease_feature
  prompt: >
    How much of what is unknown about endomyocardial fibrosis reflects genuine biological
    difficulty rather than the absence of research capacity where the disease occurs?
  kind: CURATION_TODO
  status: OPEN
  attaches_to:
  - pathophysiology#Chronic antigenic or toxic stimulus in a susceptible host
  rationale: >
    This entry has no transcriptomic, proteomic, metabolomic, or single-cell data to cite. It
    has exactly one molecular-profiling study of any kind, a plasma cytokine panel in 27
    patients, and one randomised trial, a 35-patient pilot of prednisolone that was negative.
    Its only genetic association has never been replicated, its only animal model dates from
    1996, and the only cell system in use is explicitly described by its own authors as not a
    disease model. That is the entire modern molecular literature for a disease affecting
    nearly a fifth of a screened population. Publication volume has fallen since the 1980s. These are not properties of the biology; they are properties of where the biology
    happens. The curation consequence is that absence of evidence in this entry should not be
    read as evidence of absence anywhere it appears, and that flagging a gap here is
    frequently a statement about research funding rather than about a hard scientific problem.
    This is recorded as a standing caveat over the whole entry rather than as a question with
    an experiment attached.
  evidence:
  - reference: PMID:18301727
    reference_title: "Endomyocardial fibrosis: still a mystery after 60 years."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The volume of publications on endomyocardial fibrosis has declined since the 1980s."
    explanation: Quantifies the decline in research attention to a disease of this prevalence.
  - reference: PMID:32420110
    reference_title: "Challenges in addressing the knowledge gap on endomyocardial fibrosis through community-based studies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "can be used to expose global disparities in cardiovascular research"
    explanation: The authors' own framing of the disease as an index of research inequity.
notes: >
  Scope. This entry curates tropical or idiopathic endomyocardial fibrosis, MONDO:0006746.
  It is deliberately not merged with Löffler endocarditis or with the cardiac involvement of
  hypereosinophilic syndrome, which share the end-stage lesion but have a documented cause
  and a different clinical context. Several mechanism nodes nonetheless cite hypereosinophilic
  syndrome literature, because that is where the stage-by-stage evidence exists; those
  citations are marked and their limits are discussed in the eosinophil-hypothesis discussion
  rather than glossed.

  Do not conflate this disease with endocardial fibroelastosis, OMIM 226000. That is a
  distinct congenital or infantile endocardial thickening syndrome, and the deep-research
  report explicitly flagged the risk of curating that OMIM identifier against MONDO:0006746.
  It is not curated here.

  Module conformance. Five nodes declare conformance to the fibrotic_response module. The fit
  is good on the generic arc from injury through inflammation and mesenchymal activation to
  excess matrix and organ dysfunction, but two specifics differ from the module's parenchymal
  archetype and are worth noting: the injury is intraluminal and endothelial rather than
  parenchymal, and the matrix is deposited in a thin subendothelial layer with the underlying
  myocardium comparatively spared, which is why systolic function survives and why surgical
  decortication is anatomically possible.

  Environmental exposure terms. None of the three dietary or geochemical exposures curated
  here carries an ECTO binding. A search of the ECTO exposure hierarchy returned no term for
  cassava, cerium, thorium, monazite, or rare-earth exposure, and the available broader terms
  either assert something different (exposure to cyanide would commit to a cyanogen mechanism
  the sources do not establish) or assert almost nothing (exposure to nutrient, exposure to
  soil). The exposures are therefore free text with their claims carried in the description
  and evidence, which is less queryable but not misleading.

  Histopathology term binding. The first histopathology entry carries no finding_term. The
  HistopathologyFindingTerm enum is restricted to the NCIT histopathology-result branch, which
  contains no cardiac or endocardial fibrosis morphologic concept; HP:0006685 is used on the
  corresponding phenotype but is not a member of that enum.

  Deep-research provenance. Curated from a claude_code deep-research report
  (research/Endomyocardial_Fibrosis-deep-research-claude_code.md) treated as leads only. The
  NEC preflight returned SKIP because MONDO records no causal gene for MONDO:0006746; manual
  checks against the MONDO record confirmed the entity. Three ontology identifiers suggested
  by the provider were verified against OAK and found to point at unrelated concepts
  (HP:0012765 is Widened cerebellar subarachnoid space, not Orthopnea; HP:0005177 is Premature
  arteriosclerosis, not Tricuspid regurgitation; UBERON:0002348 is epicardium, not
  endocardium). All were corrected before curation. Two provider-suggested references for the
  eosinophil-granule mechanism were checked and found to be correspondence items without
  abstracts, so the mechanism is cited from hypereosinophilic syndrome reviews carrying
  directness: INDIRECT rather than from an unquotable source.

📚

References & Deep Research

Deep Research

1

Claude Code ▸

Endomyocardial Fibrosis (EMF): Comprehensive Disease Research Report

claude-haiku-4-5-20251001, claude-sonnet-5 27 citations 2026-08-09T21:48:06.332957

Endomyocardial Fibrosis (EMF): Comprehensive Disease Research Report

1. Disease Information

Overview. Endomyocardial fibrosis (EMF) is a rare, insidious restrictive cardiomyopathy characterized by dense fibrous scarring of the ventricular endocardium — predominantly the inflow tracts and apices of the right and/or left ventricle — that obliterates ventricular cavity volume, tethers the atrioventricular (AV) valve subvalvular apparatus (papillary muscles and chordae tendineae) causing regurgitation, and produces severe diastolic dysfunction with markedly preserved systolic function. It is the most common cause of restrictive cardiomyopathy worldwide and is endemic to poor tropical and subtropical regions within roughly 15° of the equator (StatPearls, NBK513293; PMC4239813).

"Subendocardial fibrosis of the apices and inflow tracts of the right ventricle, left ventricle, or both defines the disease... This restrictive scarring prevents ventricular filling, and tethering of the papillary muscles leads to valvular regurgitation." — Bukhman, Ziegler & Parry, PLoS Negl Trop Dis 2008 (PMID: 18301727)

Key identifiers:

System	Identifier	Notes
MONDO	MONDO:0006746	"endomyocardial fibrosis"
Orphanet	ORPHA:75565	"Tropical endomyocardial fibrosis"
Disease Ontology	DOID:12932
ICD-10-CM	I42.3	"Endomyocardial (eosinophilic) disease" — the ICD bucket also covers Löffler endocarditis/eosinophilic endomyocardial disease
MedGen	C0553980
OMIM	No dedicated single-gene OMIM entry	Important disambiguation: OMIM 226000 ("Endocardial fibroelastosis; EFE") is a distinct disease — a congenital/infantile endocardial thickening syndrome (often linked to ciliopathy genes, mitochondrial/carnitine defects, viral myocarditis, or as a secondary finding in obstructed left heart lesions), not to be conflated with acquired tropical/idiopathic EMF. Do not curate OMIM:226000 against MONDO:0006746.
HPO (phenotype)	HP:0006685	"Endocardial fibrosis" (verify label via OAK before use)

Synonyms: Davies' disease/Davies disease, tropical endomyocardial fibrosis, African endomyocardial fibrosis, endomyocardial sclerosis, obscure African cardiomyopathy, eosinophilic endomyocardial disease (when linked to Löffler/hypereosinophilic pathophysiology) (GARD; StatPearls NBK513293).

Evidence base: Information is derived almost entirely from aggregated disease-level resources — hospital case series, autopsy series, and a small number of population-based echocardiographic screening studies (notably the 2008 Mozambique study) — rather than large-scale EHR/biobank data, reflecting both the rarity of formal cohorts and the resource-limited settings where EMF is endemic.

Sources: - Endomyocardial Fibrosis - StatPearls - Endomyocardial Fibrosis: Still a Mystery after 60 Years - PLOS NTD (PMID: 18301727) - Endomyocardial fibrosis: A form of endemic restrictive cardiomyopathy - PMC - Orphanet: Tropical endomyocardial fibrosis - GARD - Endomyocardial fibrosis - OMIM 226000 - Endocardial Fibroelastosis

2. Etiology

EMF has no single confirmed cause; the current model is multifactorial, requiring convergence of infectious/immune stimuli, malnutrition, environmental exposures, and host genetic susceptibility in the context of poverty.

"No single proposed factor can explain the occurrence of EMF worldwide." — cdt.amegroups.org review (Cardiovasc Diagn Ther)

Disease causal factors — historically proposed hypotheses

Helminth/parasite–eosinophilia hypothesis: Filariasis, schistosomiasis, and other chronic helminthic infections drive sustained hypereosinophilia; eosinophil granule protein-mediated cardiotoxicity (see Mechanism section) is the leading mechanistic model. Ive & Brockington (Nigeria) found filariasis in ~100% of 42 angiographic EMF cases vs. 44% of 115 controls (cited in PMID: 18301727), though the hypothesis fails to explain the absence of EMF in other high-helminth-burden regions (e.g., parts of Southeast Asia).
Löffler endocarditis / hypereosinophilic syndrome (HES) equivalence: Histological and echocardiographic comparisons (Brockington & Olsen 1975; Davies 1983) found the fibrotic end-stage of Löffler endocarditis indistinguishable from EMF, suggesting a shared final common pathway of eosinophil-mediated endomyocardial injury regardless of the trigger for eosinophilia (idiopathic, parasitic, or clonal/neoplastic).
Nutritional/toxic hypotheses: Cassava-based diets combined with severe protein deprivation were causally tested — feeding uncooked cassava to Cercopithecus aethiops (African green monkeys) produced EMF-like cardiac lesions (vs. no lesions on a banana-diet control), supporting a cassava/protein-deficiency mechanism (linked to cyanogenic glycoside/cerium toxicity). The competing "serotonin–plantain" hypothesis was tested by feeding plantains to guinea pigs, rats, and Patas monkeys but failed to reproduce EMF lesions and was abandoned by the 1970s (PMID: 18301727).
Geochemical/toxin exposure: Cerium and thorium in monazite-rich soils (e.g., coastal Kerala, India) have been speculatively linked to regional clustering, without confirmatory studies.
Autoimmunity: Elevated immunoglobulins and circulating anti-myosin antibodies (against actin, tropomyosin, and HSP-70) found in 53.6% of EMF patients vs. 10% of controls (see Genetic/Molecular section) support an autoimmune amplification loop, possibly triggered by molecular mimicry after infection (PMID: 20422043).
Malaria/immune dysregulation: Migration-associated changes in anti-malarial and anti-heart antibody titers were noted among Rwanda–Burundi migrant populations developing EMF in Uganda, though Plasmodium species distribution does not match EMF geography.

Risk factors

Genetic risk factors: - Familial clustering and ethnic-group concentration strongly suggest heritable susceptibility (PMID: 757895, familial EMF in Zambia). - The only formal genetic association study to date found HLA-B*58 associated with EMF in Mozambique (p=0.03) and HLA-A*02:02 in Uganda (p=0.005) (Beaton et al., Glob Cardiol Sci Pract 2014, PMID: 25780800). No genome-wide association study has yet been performed or validated these findings. - In the eosinophilic (Löffler-variant) end of the spectrum, the FIP1L1-PDGFRA fusion gene (constitutively active tyrosine kinase from an interstitial 4q12 deletion) drives clonal hypereosinophilia with cardiac (Löffler endocarditis/EMF-pattern) involvement in a subset of chronic eosinophilic leukemia patients — a somatic, acquired lesion rather than germline (PMC12082641, PMC10484160, PMC10217393).

Environmental risk factors: - Extreme poverty, rural residence, subsistence farming, going barefoot, and cassava-based diets (Uganda case-control data cited in PMC12701864/PMID: 41399600 and PMID: 18301727). - Chronic helminthic (filarial, schistosomal) and malarial infection burden. - Magnesium and protein-calorie malnutrition. - Geography: equatorial low-lying humid tropical zones — coastal Tanzania/Mozambique, southern Nigeria, Uganda, Kerala (India), Guangxi Province (China), Bahia/Colombia (South America).

Protective factors: No specific genetic or environmental protective factors have been formally identified in the literature; declining incidence in some hospital series has been attributed non-specifically to "improving healthcare and living standards" (PMC4239813) — i.e., socioeconomic/nutritional/parasite-control improvement rather than a defined protective exposure or allele.

Gene–environment interactions: The prevailing model is that HLA-conferred immune-response variability modulates the intensity/character of the host response (Th2-skewed, eosinophil/mast-cell-driven inflammation) to a chronic antigenic trigger (helminth, malarial, or nutritional/toxic) that is itself environmentally determined by poverty and geography — i.e., genetic susceptibility determines who among the exposed develops fibrotic disease (PMID: 25780800).

Sources: - Endomyocardial Fibrosis: Still a Mystery after 60 Years (PMID: 18301727) - Genetic susceptibility to endomyocardial fibrosis (PMID: 25780800) - Endomyocardial fibrosis: familial and other cases from northern Zambia (PMID: 757895) - A Narrative Review on Endomyocardial Fibrosis (PMC12701864 / PMID: 41399600) - Loeffler endocarditis revealing chronic eosinophilic leukaemia with FIP1L1-PDGFRA rearrangement (PMC12082641)

3. Phenotypes

EMF phenotypes span cardiac structural/functional signs, systemic congestive symptoms, hematologic/laboratory abnormalities, and constitutional findings from chronic malnutrition. Frequencies below are drawn from hospital case series (Iroegbu et al., Cardiovasc Diagn Ther; Mozambique population study PMID: 18596273) and should be treated as approximate/series-specific.

Cardiac signs and symptoms

Phenotype	Description	Suggested HPO term*
Restrictive diastolic dysfunction	Impaired ventricular filling despite preserved ejection fraction	HP:0001723 (restrictive cardiomyopathy) — verify
Endocardial fibrosis	Dense fibrous endocardial thickening at apex/inflow tract	HP:0006685
Dyspnea / exertional dyspnea	Left-sided disease	HP:0002094
Orthopnea	Left-sided disease	HP:0012765 — verify
Ascites (often disproportionate to peripheral edema)	Right-sided/biventricular disease; exudative, lymphocyte-predominant	HP:0001541
Hepatomegaly / hepatosplenomegaly	Right-sided disease	HP:0002240
Elevated jugular venous pressure / giant "v" waves	Tricuspid regurgitation	—
Mitral regurgitation	Chordal/papillary muscle tethering	HP:0001653
Tricuspid regurgitation	Chordal/papillary muscle tethering	HP:0005177
Atrial enlargement (biatrial)	Compensatory to restrictive ventricles	HP:0005120 — verify
Atrial fibrillation	Reported in ~30–40% of cases	HP:0005110
Cardiac thrombus (ventricular apex, atrial)	Mural thrombus formation	—
Pericardial/pleural effusion	Advanced disease	HP:0002202 (pleural effusion)
Cardiomegaly	On CXR	HP:0001640
Sudden cardiac death	Reported in pediatric series (4/55 cases, ages 1–11)	HP:0001645 — verify

Systemic/constitutional signs

Exophthalmos, central cyanosis, lip/gum hyperpigmentation (distinctive but non-specific findings reported in African case series)
Cachexia, growth stunting, malnutrition (chronic disease)
Clubbing
Testicular atrophy and sexual dysfunction in males (advanced chronic disease)

Laboratory abnormalities

Eosinophilia during the acute/inflammatory phase (variable; not present once fibrotic stage is reached)
Hypoalbuminemia in chronic phase
Elevated NT-proBNP/BNP and high-sensitivity troponin (disease-progression/prognostic markers, not diagnostic)
Elevated plasma cytokines (see Mechanism section): TNF-α, IL-4, IL-10
Circulating anti-myosin (anti-actin, anti-tropomyosin, anti-HSP70) IgG/IgM autoantibodies in a disease-activity-correlated subset (PMID: 20422043)

Phenotype characteristics

Age of onset: Bimodal — childhood peak (~first decade of life; "more than half of reported EMF cases originating in sub-Saharan Africa," per PMC12701864) and a secondary adult peak in women of childbearing age.
Severity/progression: Ranges from asymptomatic/subclinical (in the Mozambique population screen, only 22.7% of 211 EMF-positive subjects were symptomatic, PMID: 18596273) to end-stage NYHA class III/IV heart failure. In symptomatic hospital cohorts, 62–98% present in NYHA class III/IV (cdt.amegroups.org review; Iroegbu et al.).
Course: Chronic and progressive once fibrotic; historically an acute febrile/eosinophilic myocarditic phase (Davies stage 1, up to ~5 months) precedes a subacute thrombotic stage (Davies stage 2, starting ~10 months) and finally the irreversible fibrotic stage (Davies stage 3, over years).
Ventricular distribution: Biventricular ~50–55%, isolated LV ~28–40%, isolated RV ~10–28% (varies by series; NEJM Mozambique study: biventricular 55.5%, right-sided 28.0%, presumably left-sided the remainder) (PMID: 18596273).

Quality of life impact

Formal disease-specific quality-of-life instruments (EQ-5D, SF-36) have not been reported for EMF specifically. Functional impact is inferred from NYHA class distributions — the majority of clinically ascertained (hospital-based) patients present in NYHA III/IV, i.e., marked-to-severe limitation of ordinary activity — and from the socioeconomic/constitutional burden (growth failure, cachexia, sexual dysfunction) documented in pediatric and adult case series.

*HPO term suggestions are provisional and should be verified against the ontology (label match) before curation, per standard practice.

Sources: - A population study of endomyocardial fibrosis in a rural area of Mozambique (PMID: 18596273) - Endomyocardial fibrosis - Iroegbu (Cardiovasc Diagn Ther) - Endomyocardial Fibrosis - StatPearls

4. Genetic/Molecular Information

Causal genes: EMF (the idiopathic/tropical form) is not a single-gene Mendelian disorder — no causal gene has been established, and there is no dedicated OMIM phenotype entry for it (distinguishing it from OMIM:226000 endocardial fibroelastosis, a different, largely infantile/congenital disease with heterogeneous — sometimes monogenic ciliopathy-related — causes).

Associated genetic/genomic findings: - HLA-B*58 (Mozambique) and HLA-A*02:02 (Uganda) — population-specific susceptibility alleles, PMID: 25780800. These require replication and are not diagnostic markers. - FIP1L1-PDGFRA fusion (interstitial 4q12 deletion producing a constitutively active PDGFRA tyrosine kinase) — a somatic driver of clonal hypereosinophilic syndrome/chronic eosinophilic leukemia, a recognized cause of the Löffler-endocarditis/EMF phenotype in a subset of patients, and clinically actionable because these patients respond to imatinib (tyrosine kinase inhibitor) (PMC12082641, PMC10484160). This is a somatic, not germline, genetic lesion, relevant to a specific EMF-associated etiologic subset rather than tropical/idiopathic EMF as a whole. - No pathogenic germline variant, chromosomal abnormality, or copy-number variant has been established as causal for classic tropical/nutritional EMF.

Autoantibody/molecular immune findings: - IgG antibodies against myocardial proteins of 35 kDa (actin), 42 kDa (tropomyosin), and 70 kDa (HSP-70) detected in 53.6% of 56 Mozambican EMF patients vs. 10% of 10 controls (p<0.05); IgM antibodies in 19.6% vs. 0%. Antibody reactivity correlated with disease activity (mean 19.6±3.7 antibodies in active disease vs. 7.1±3.3 in remission) (PMID: 20422043).

Cytokine/molecular profiling (plasma, n=27 EMF patients vs. 38 controls, Bossa et al. 2014, PLoS ONE, DOI: 10.1371/journal.pone.0108984, PMCID: PMC4193862): | Cytokine | EMF patients | Controls | p-value | % positive in EMF | |---|---|---|---|---| | TNF-α | 2.77 ± 4.64 pg/mL | 0.94 ± 0.24 pg/mL | 0.006 | 77.7% | | IL-4 | 4.51 ± 7.79 pg/mL | 1.22 ± 0.87 pg/mL | 0.001 | 88.8% | | IL-10 | 4.11 ± 5.27 pg/mL | 0.99 ± 0.89 pg/mL | 0.0001 | 92.6% | | IL-6, IFN-γ, IL-2 | Not significantly different | — | — | — |

Interpretation: "a mixed pro- and anti-inflammatory/Th2 circulating cytokine profile" consistent with a persistent inflammatory stimulus with compensatory anti-inflammatory (Th2/IL-10) upregulation, possibly residual from prior helminthic infection.

Epigenetic information: No EMF-specific DNA methylation, histone modification, or chromatin studies were identified in the literature search — this is an open gap.

Functional consequences: Because no causal germline gene/variant is established, LOSS_OF_FUNCTION/GAIN_OF_FUNCTION functional-impact categorization does not apply to a variant in the way it would for a monogenic disease; the FIP1L1-PDGFRA subset is the clearest example of a gain-of-function somatic lesion (constitutive kinase activation) driving eosinophil-mediated cardiotoxicity in a specific EMF-associated etiology.

Suggested HGNC/gene annotations (for the eosinophilic/Löffler-variant subtype only): PDGFRA (hgnc:8803), FIP1L1 (hgnc:26845) — verify via HGNC before curation.

Sources: - Genetic susceptibility to endomyocardial fibrosis (PMID: 25780800) - Presence of Circulating Anti-Myosin Antibodies in Endomyocardial Fibrosis (PMID: 20422043) - Plasma Cytokine Profile in Tropical Endomyocardial Fibrosis (PMC4193862) - Loeffler endocarditis revealing chronic eosinophilic leukaemia with FIP1L1-PDGFRA rearrangement (PMC12082641)

5. Environmental Information

Environmental factors: - Cassava (manioc) consumption combined with severe protein deprivation — experimentally reproduced EMF-like cardiac lesions in African green monkeys (Cercopithecus aethiops) fed uncooked cassava vs. banana-fed controls. - Cerium/thorium exposure from monazite-rich soils (speculative, regional correlation only, e.g., coastal Kerala). - Magnesium deficiency.

Lifestyle/socioeconomic factors: - Extreme poverty; subsistence farming; going barefoot (a marker of poverty and of soil-transmitted helminth exposure) — Ugandan case-control study found associations between EMF and "markers of poverty such as farming, lack of shoes, and cassava-based diets" (PMID: 18301727). - Rural residence in low-lying, humid, equatorial regions. - Chronic malnutrition/protein-calorie deficiency.

Infectious agents implicated (none proven definitively causal): - Helminths: filaria, Schistosoma spp. - Plasmodium spp. (malaria) — via immune dysregulation/antibody cross-reactivity hypothesis rather than direct cardiac invasion. - Coxsackievirus (proposed as a possible triggering acute myocarditic insult in some hypotheses).

Suggested ECTO exposure terms (to verify via OAK before curation): exposure to cassava/cyanogenic glycosides, exposure to helminth antigens, exposure to Plasmodium falciparum antigens, dietary protein deficiency exposure.

Sources: As cited in Sections 2 and 3 above (PMID: 18301727; PMC12701864/PMID: 41399600).

6. Mechanism / Pathophysiology

Causal chain overview (from trigger to clinical manifestation)

Chronic antigenic/toxic stimulus (helminth infection, malaria, cassava/protein malnutrition)
   → (in genetically susceptible hosts, e.g., HLA-B*58/HLA-A*02:02)
Sustained eosinophilia / Th2-skewed immune activation (elevated IL-4, IL-10, TNF-α)
   → Eosinophil degranulation in endocardium: release of eosinophil cationic protein (ECP),
     major basic protein (MBP), eosinophil-derived neurotoxin, reactive oxygen species
   → Endothelial and myocyte injury (necrosis) — Davies Stage 1: acute eosinophilic
     (necrotic) myocarditis/endocarditis (up to ~5 months)
   → ECP-mediated activation of coagulation factors + MBP-mediated platelet activation
     → Mural thrombus formation at ventricular apex and beneath posterior mitral leaflet
       — Davies Stage 2: thrombotic stage (from ~10 months, over several years)
   → Organization of thrombus + fibroblast activation/excess collagen and ECM deposition
     → Dense acellular fibrocollagenous endocardial scar — Davies Stage 3: fibrotic
       (healed) stage
   → Endocardial fibrosis obliterates ventricular apex/inflow tract, tethers papillary
     muscles/chordae to the ventricular wall
   → Restrictive diastolic physiology + AV valve regurgitation (mitral and/or tricuspid)
   → Atrial dilation (compensatory) → atrial fibrillation, further thromboembolic risk
   → Congestive heart failure, pulmonary hypertension (left-sided disease),
     systemic venous hypertension/ascites/hepatomegaly (right-sided disease)

Autoimmune amplification (anti-myosin/actin/tropomyosin/HSP-70 antibodies) may perpetuate myocardial injury independent of ongoing eosinophilic infiltration, particularly in chronic/relapsing disease.

Molecular pathways

Th2/eosinophil-driven inflammatory pathway: IL-4/IL-10-skewed cytokine milieu with TNF-α co-elevation (PMC4193862).
PDGFRA/tyrosine kinase signaling: constitutively activated in the FIP1L1-PDGFRA somatic-fusion subset, driving eosinophil clonal proliferation (relevant to Löffler-variant/EMF overlap).
Coagulation cascade activation: eosinophil cationic protein directly activates coagulation factors, and MBP stimulates platelet activation — a distinctive eosinophil-to-thrombosis mechanistic link (JIR review, DOI: 10.2147/JIR.S458692, PMCID: PMC10984210).
Fibrotic/ECM pathway: excessive fibroblast activation and collagen/extracellular-matrix deposition in the endocardial subendothelial layer (mechanistically convergent with the dismech fibrotic_response module pattern: tissue injury → inflammation → mesenchymal/fibroblast activation → excessive ECM → organ dysfunction).

Cellular processes

Eosinophil degranulation and cytotoxicity
Endothelial injury
Myocyte necrosis (subendocardial)
Platelet activation and thrombus organization
Fibroblast activation and excessive collagen synthesis (myofibroblast-like phenotype implied but not explicitly characterized at single-cell resolution in the literature reviewed)
Chronic lymphocytic/mononuclear inflammatory infiltration (persists into the fibrotic stage in some series)
Neovascularization within subendocardial fibrotic tissue

Protein dysfunction / biochemical abnormalities

Eosinophil cationic protein (ECP) and major basic protein (MBP) act as direct mediators of endothelial and myocardial cytotoxicity and of pathological coagulation activation.
No structural protein misfolding/aggregation mechanism (distinguishing EMF from, e.g., amyloidosis, another restrictive-cardiomyopathy differential).

Immune system involvement

Central and defining: eosinophil-mediated tissue injury (whether from reactive/secondary eosinophilia due to parasitic infection, idiopathic hypereosinophilia, or clonal/neoplastic hypereosinophilic syndrome with FIP1L1-PDGFRA), compounded by autoimmune anti-myocardial antibody production in a subset.

Tissue damage mechanisms

Eosinophil-granule-protein cytotoxicity → necrosis → thrombosis → fibrotic scarring (a distinctive three-stage, immune-cell-initiated fibrogenesis mechanism, mechanistically related to — but histologically and etiologically distinct from — classic tissue-injury-driven fibrotic_response chains seen in organ fibrosis elsewhere in the KB).

Molecular profiling

Transcriptomics/proteomics/metabolomics/lipidomics/single-cell/spatial data: No dedicated omics datasets for human EMF cardiac tissue were identified in this search (a notable knowledge gap — EMF is markedly under-studied by modern molecular methods relative to its disease burden, largely due to being endemic in resource-limited settings without omics infrastructure).
Histopathology (traditional, most detailed available "molecular profiling" surrogate):
Gross: atrial dilation, apical mural thrombus, reduced ventricular cavity size, AV annular dilation.
Microscopic: dense acellular fibrocollagenous endocardial thickening; lymphocyte-predominant infiltrate; minimal myocardial (as opposed to endocardial) tissue loss; subendocardial neovascularization; coronary vessel changes (medial sclerosis, intimal proliferation, plexiform lesions) reported in one pediatric surgical/histopathology series (mean endocardial thickness 3,000 ± 1,519 µm, maximum 5,591 µm) (cdt.amegroups.org).

Suggested ontology terms (verify before curation)

GO (biological process): GO:0030198 extracellular matrix organization; GO:0006954 inflammatory response; GO:0043534 blood vessel endothelial cell migration (angiogenesis-adjacent); collagen biosynthesis/fibril organization terms.
CL (cell type): CL:0000771 eosinophil; CL:0000057 fibroblast; CL:0000097 mast cell; CL:0000236 (B cell, for autoantibody production context).
UBERON: UBERON:0002348 endocardium; UBERON:0002080 right ventricle; UBERON:0002084 left ventricle; cardiac papillary muscle and chordae tendineae terms.
CHEBI: eosinophil cationic protein / RNase 3 and major basic protein are proteins rather than small molecules — represent via UniProt/gene rather than CHEBI.

Sources: - In-Depth Review of Loeffler Endocarditis: What Have We Learned? (PMC10984210) - Endomyocardial fibrosis - Iroegbu (Cardiovasc Diagn Ther) - The cardiotoxicity of eosinophils (PMC2417450) - Plasma Cytokine Profile in Tropical Endomyocardial Fibrosis (PMC4193862)

7. Anatomical Structures Affected

Organ level: - Primary: Heart — right ventricle, left ventricle (either alone or, most commonly, biventricular), atrioventricular valves (mitral, tricuspid), atria (secondary dilation). - Secondary/complication-driven: Liver (congestive hepatomegaly), spleen (splenomegaly), lungs (pulmonary hypertension, pleural effusion, pulmonary congestion in left-sided disease), peritoneum (ascites — notably exudative/lymphocytic, suggesting a degree of peritoneal inflammatory involvement rather than pure transudative congestion), coronary vasculature (secondary sclerotic/proliferative changes reported in some histopathologic series). - Body systems: Cardiovascular (primary); hepatic, pulmonary, and hematologic (thromboembolic) systems secondarily.

Tissue/cell level: - Endocardium (subendothelial layer) — primary site of fibrous deposition. - Myocardium — subendocardial injury; relatively spared compared to endocardium. - Cell populations: eosinophils (infiltrating), fibroblasts (activated, ECM-producing), lymphocytes/mononuclear cells (chronic infiltrate), endothelial cells (injured), platelets (thrombus formation).

Subcellular level: No specific organelle-level pathology (e.g., mitochondrial, ER) has been characterized as central to EMF pathogenesis in the literature reviewed; this contrasts with some other cardiomyopathies (e.g., storage/metabolic cardiomyopathies) and represents a gap.

Localization: - Apex and inflow tract predominate (both ventricles can be affected). - Right ventricle: trabecular cavity obliteration, apical retraction, tricuspid valve tethering. - Left ventricle: apical obliteration (rounded "obliterated apex" morphology on echo), posterior mitral leaflet/chordal involvement (fibrosis characteristically engulfs the posterior mitral leaflet). - Laterality: Right-sided, left-sided, or biventricular — biventricular is the most common pattern (~50–55% in major series).

Sources: As cited above (StatPearls NBK513293; PMC4239813; PMID: 18596273).

8. Temporal Development

Onset: - Typically pediatric/adolescent onset (more than half of reported cases arise in the first decade of life), with a secondary adult-onset peak in women of childbearing age. Onset pattern is classically an insidious acute febrile illness (facial swelling, pruritus, eosinophilia) that may be mistaken for viral myocarditis or acute rheumatic fever, though many cases are only detected later in the fibrotic/chronic stage, or incidentally via echocardiographic screening (subclinical disease).

Progression — Davies three-stage model: 1. Acute (necrotic) stage — up to ~5 months; eosinophilic myocarditis with subendocardial necrosis; may present as fulminant heart failure/cardiogenic shock or be entirely asymptomatic/missed. 2. Thrombotic (intermediate/subacute) stage — beginning ~10 months post-onset, lasting several years; mural thrombus formation at the apex and behind the posterior mitral leaflet. 3. Fibrotic (chronic/healed) stage — the stage at which most patients present clinically; endocardium replaced by dense collagenous scar; restrictive physiology and valvular regurgitation dominate the clinical picture. This stage is essentially irreversible.

Rate/course: Variable — can be relatively indolent (subclinical disease detected on population screening, as in 77% of the Mozambique EMF-positive cohort) or rapidly progressive to severe heart failure and death. Once in the fibrotic stage, the disease course is chronic and progressive, without spontaneous remission; medical therapy does not appreciably alter the underlying fibrotic process (StatPearls NBK513293; a randomized placebo-controlled trial of prednisolone in Uganda found no significant benefit in preventing ascites reaccumulation, PMCID: PMC4678569 — see Treatment section).

Critical periods: The acute eosinophilic/necrotic stage represents the theoretical intervention window before irreversible fibrosis sets in (rationale for anti-eosinophilic/immunosuppressive therapy trials), but this stage is rarely captured clinically because of its nonspecific presentation and the resource constraints of endemic settings.

Sources: - Endomyocardial Fibrosis: Diagnosis and Management (Dove Press / JVD) - A population study of endomyocardial fibrosis in a rural area of Mozambique (PMID: 18596273) - The safety and efficacy of prednisolone... (PMC4678569)

9. Inheritance and Population

Epidemiology: - Prevalence: The only rigorous population-based echocardiographic screening study (rural Mozambique, n=1,063, all ages, PMID: 18596273) found an overall prevalence of 19.8% (211/1,063; 95% CI 17.4–22.2), highest in ages 10–19 (28.1%), and higher in males than females (23.0% vs. 17.5%, p=0.03) — a strikingly high figure reflecting substantial subclinical/mild disease burden not captured by hospital-based series. Note this is markedly higher than clinically ascertained hospital prevalence figures and reflects a broad echocardiographic case definition including mild disease. - Hospital-based series report EMF as accounting for up to ~20% of heart-failure/echocardiography referrals in endemic African centers (e.g., Kampala) and as the 4th most common cause of adult cardiac disease in some equatorial African nations. - One review cites a global burden estimate of ~12 million affected persons, predominantly in sub-Saharan Africa (cdt.amegroups.org) — this figure should be treated cautiously given the absence of large-scale multinational surveillance; it likely derives from extrapolation of regional prevalence data (such as the Mozambique 19.8% figure) rather than direct enumeration. - Historical literature documents >2,400 published cases worldwide, ~50% from sub-Saharan Africa and ~25% from Uganda alone (PMID: 18301727) — though this reflects publication/ascertainment bias rather than true incidence. - Hospital-series incidence appears to be declining over recent decades, plausibly linked to improved nutrition, parasite control, and healthcare access, though this has not been rigorously quantified prospectively.

Inheritance pattern: Not Mendelian — EMF is a complex/multifactorial disease. No autosomal dominant/recessive/X-linked/mitochondrial pattern has been established. Familial clustering (PMID: 757895) and HLA associations (PMID: 25780800) support polygenic/complex susceptibility rather than single-gene inheritance. Penetrance, expressivity, anticipation, germline mosaicism, and founder-effect concepts are therefore not directly applicable in the Mendelian sense; however, the HLA-B*58 and HLA-A*02:02 associations function analogously to susceptibility-locus "carrier frequency" concepts and would require population-specific allele-frequency data (not identified in this search) to quantify.

Population demographics: - Geographic distribution: Endemic — sub-Saharan Africa (Uganda, Mozambique, Nigeria, Cameroon, Congo, Malawi, Zambia most represented), South Asia (Kerala, India), East Asia (Guangxi Province, China), South America (Bahia, Brazil; Colombia). Rare sporadic cases reported in non-endemic/Western populations (e.g., a Western European case report, PMC7319822). - Sex ratio: Roughly equal in childhood-onset disease; adult-onset disease reported to affect women roughly twice as often as men in some series (though the Mozambique population screen found higher male prevalence overall — sex-ratio findings are series-dependent and possibly stage/age-dependent). - Age distribution: Bimodal — childhood/adolescent peak and adult (childbearing-age women) peak. - Socioeconomic gradient: Strongly associated with poverty; a recognized "neglected disease of poverty."

Sources: - A population study of endomyocardial fibrosis in a rural area of Mozambique (PMID: 18596273) - Endomyocardial Fibrosis: Still a Mystery after 60 Years (PMID: 18301727) - Endomyocardial fibrosis - Iroegbu (Cardiovasc Diagn Ther) - Idiopathic endomyocardial fibrosis in a Western European: a case report (PMC7319822)

10. Diagnostics

Clinical laboratory tests: No definitive/diagnostic blood test exists. Eosinophilia may be present in the acute inflammatory phase but is often absent by the fibrotic stage. Hypoalbuminemia is common in chronic disease. Elevated NT-proBNP/BNP and high-sensitivity troponin correlate with disease severity/progression and prognosis but are non-specific.

Electrocardiography: Low-voltage QRS, nonspecific ST-/T-wave abnormalities, AV block, bundle branch block, left/biatrial enlargement patterns.

Chest radiography: Cardiomegaly, atrial enlargement, pulmonary vascular congestion, occasional endomyocardial calcification, pleural/pericardial effusion.

Echocardiography — the primary diagnostic modality. Key structural findings: apical cavity obliteration (right and/or left ventricle), "mushroom sign" apical distortion, dense endocardial echogenicity, mural thrombus/spontaneous contrast, AV valve tethering with regurgitation, biatrial enlargement, restrictive (dip-and-plateau) diastolic filling pattern (short deceleration time, shortened isovolumic relaxation time). Left-ventriculography analog: apical obliteration; M-mode may show a distinctive "M-shaped" septal motion pattern.

Diagnostic scoring systems (Mocumbi criteria): - Definite diagnosis requires 2 major criteria, or 1 major + 2 minor criteria. - Major criteria: obliteration of the RV or LV apex; thrombi or spontaneous contrast without severe global ventricular dysfunction; retraction of the RV apex; AV valve dysfunction from adhesion of the valve apparatus to the ventricular wall. - Minor criteria: restrictive mitral/tricuspid inflow pattern; pulmonary valve diastolic opening; enlarged atrium with normal-sized ventricle. - A quantitative severity score (weighted per criterion) stratifies disease as mild (<8), moderate (8–15), severe (>15) in the original Mocumbi formulation; a related pediatric grading (4–6 mild, 7–9 moderate, 10–12 severe) has also been reported in a separate series (cdt.amegroups.org), indicating some variation in scoring implementations across studies — the exact cut-points should be verified against the primary source before formal curation.

Cardiac MRI: More sensitive than echocardiography for detecting intracardiac thrombus and for early/subclinical disease; late gadolinium enhancement (LGE) shows continuous subendocardial enhancement from subvalvular regions to the apex ("double V" / "three-layered" sign), correlating with histopathologic fibrosis. LGE-quantified fibrosis volume has been reported as an independent predictor of mortality (PMC12701864/PMID: 41399600). MRI is valuable for preoperative planning and treatment-response monitoring.

Myocardial contrast echocardiography (MCE): Adjunctive tool for apical obliteration/thrombus detection when conventional imaging is limited.

Cardiac catheterization: Rarely required now; shows a classic restrictive "dip-and-plateau" ventricular pressure pattern; angiography demonstrates apical cavity obliteration.

Endomyocardial biopsy: Can demonstrate subendocardial fibrosis and thrombus, but limited utility due to patchy distribution of fibrosis and procedural risk (risk of thrombus dislodgement/embolization in a fibrotic, thrombus-laden ventricle).

Genetic testing: Not part of the standard diagnostic pathway for classic tropical/idiopathic EMF (no established causal gene). For suspected hypereosinophilic-syndrome-driven (Löffler/eosinophilic) EMF, FIP1L1-PDGFRA fusion testing (FISH or RT-PCR) is clinically actionable, as fusion-positive patients respond to imatinib.

Clinical criteria / differential diagnosis: Key differentials include viral myocarditis (acute stage), cardiac amyloidosis, cardiac sarcoidosis, dilated cardiomyopathy, left ventricular noncompaction, carcinoid heart disease, anthracycline cardiotoxicity, constrictive pericarditis, and radiation-induced cardiomyopathy — all part of the broader restrictive-cardiomyopathy/heart-failure-with-preserved-EF differential.

Screening: No formal national/international newborn or population screening program exists. The single major population-based echocardiographic prevalence survey (Mozambique, PMID: 18596273) demonstrates the feasibility and yield of community echocardiographic screening in endemic areas but has not been scaled into a routine screening program.

Sources: - Endomyocardial Fibrosis - StatPearls - A Narrative Review on Endomyocardial Fibrosis (PMC12701864 / PMID: 41399600) - Endomyocardial fibrosis - Iroegbu (Cardiovasc Diagn Ther) - Left ventricle endomyocardial fibrosis: a case report (PMC10422788)

11. Outcome/Prognosis

Survival/mortality (untreated/medically managed): - Historical Ugandan autopsy series (1959–1969): average survival ~2 years after symptom onset. - Broadly cited figure: "75% mortality within 2 years" / "one-third to one-half of patients with advanced disease dying within 2 years" with medical management alone (figures vary by series and disease-stage-at-presentation). - Atrial fibrillation is associated with worse prognosis.

Surgical outcomes: - Operative (30-day) mortality: ~15–21.7% across major surgical series; one series reported 21.7% 30-day mortality plus 13% late mortality within the first 2 postoperative years. - Life-table survival including operative mortality: ~67% at 2 years, ~55–68% at up to 17 years in selected surgical cohorts; a more recent Mozambican surgical series reported ~76.5% 5-year survival with 70.9% of operated patients showing functional improvement. - Recurrence: Fibrosis recurrence requiring reoperation in ~4–18.8% of surgical patients across series; EMF appearing in the previously unaffected contralateral ventricle in ~8.8% in one series. - Surgery is explicitly regarded as palliative — it corrects structural/valvular consequences but does not alter the underlying fibrotic disease process, and recurrence is well documented.

Morbidity/functional outcomes: - The majority of clinically ascertained (hospital-referred) patients present in NYHA class III/IV (62–98% across cited series). - Postoperative functional improvement is achievable in a substantial subset (e.g., 70.9% improved in one series; younger/less advanced patients achieving NYHA I–II postoperatively in a pediatric series), but a meaningful minority show no improvement or clinical deterioration. - Complications: heart failure, atrial fibrillation, AV block, thromboembolism (stroke, pulmonary embolism), progressive valvular dysfunction, pulmonary hypertension, infective endocarditis susceptibility, pericardial effusion, sudden cardiac death.

Prognostic factors/biomarkers: Advanced diastolic dysfunction, severe atrial enlargement, biventricular involvement, extensive fibrosis/thrombus burden on cardiac MRI, elevated NT-proBNP, and pulmonary hypertension are cited as predictors of poor outcome; LGE-quantified fibrosis volume on cardiac MRI independently predicts mortality (PMC12701864/PMID: 41399600).

Sources: - Endomyocardial fibrosis: Early and late results of surgery in 20 patients - Surgery for endomyocardial fibrosis revisited (Eur J Cardiothorac Surg) - Endomyocardial fibrosis - Iroegbu (Cardiovasc Diagn Ther) - A Narrative Review on Endomyocardial Fibrosis (PMC12701864 / PMID: 41399600)

12. Treatment

Pharmacotherapy (symptomatic/supportive; no disease-modifying drug established): - Diuretics (loop diuretics — furosemide, torasemide) for congestive symptoms (NCIT candidate: Pharmacotherapy NCIT:C15986; specific class terms to be verified). - ACE inhibitors and beta-blockers — standard heart-failure adjuncts, though restrictive physiology limits their hemodynamic benefit relative to dilated cardiomyopathy. - Anticoagulation (warfarin; direct oral anticoagulants limited by cost/access in endemic settings) for documented intracardiac thrombus/atrial fibrillation. - Corticosteroids (prednisolone): Tested in a double-blind, randomized, placebo-controlled trial in Uganda (n=35; 1 mg/kg/day, max 60 mg) for prevention of ascites reaccumulation in EMF: primary outcome (progression to grade 3 ascites) occurred in 60% of prednisolone-treated vs. 86% of placebo-treated patients (RR 0.70, 95% CI 0.43–1.11, p=0.12) — not statistically significant, though the drug was safe (PMCID: PMC4678569). This is the only identified randomized controlled trial of a disease-directed medical therapy in EMF and represents a key piece of negative-evidence for immunosuppressive intervention at the (typically late) disease stage studied. - Rate/rhythm control (beta-blockers, digoxin) for atrial fibrillation.

Advanced/targeted therapeutics (for the eosinophilic/Löffler-variant subset specifically): - Imatinib (tyrosine kinase inhibitor) — first-line for FIP1L1-PDGFRA-fusion-positive hypereosinophilic syndrome/Löffler endocarditis; achieves eosinophil normalization and echocardiographic improvement. - Mepolizumab (anti-IL-5 monoclonal antibody) — used as an eosinophil-targeting immunomodulator in HES/Löffler endocarditis, though evidence specific to established fibrotic EMF is limited (most benefit expected in the pre-fibrotic/acute eosinophilic stage). - Interferon-alfa — reported for corticosteroid/imatinib-resistant HES-associated cardiac disease.

Surgical/interventional: - Endocardiectomy (endocardial decortication) ± mitral and/or tricuspid valve repair or replacement, typically via median sternotomy with cardiopulmonary bypass — the mainstay definitive intervention for NYHA III/IV disease. NCIT candidates: Surgical Procedure (NCIT:C15329), Orthopedic Surgical Procedure not applicable; a cardiac-surgery-specific NCIT term should be verified. - Cavopulmonary connection (Fontan-type) procedures have been proposed as beneficial adjuncts for severe right-ventricular EMF in some case reports. - Heart transplantation: Not an established/first-line therapy (StatPearls notes "no established benefit"), but case reports document successful outcomes — e.g., a patient with FIP1L1-PDGFRA-associated EMF alive and asymptomatic 5 years post-transplant, and a case report describing 2-year good graft function with vigilance for possible disease recurrence in the allograft (PMCID: PMC12046388) — an important, still poorly characterized risk given EMF's presumed ongoing systemic (immune/eosinophilic) driver.

Experimental/investigational: No disease-specific investigational agents in active clinical trials for classic tropical EMF were identified; research priorities (per PMID: 18301727) include measuring inflammatory markers (CRP, TNF-α), studying FIP1L1-PDGFRA prevalence in broader EMF cohorts, examining serotonin receptor polymorphisms, and conducting further population-based echocardiographic surveys.

Treatment outcomes: See Prognosis section — surgical endocardiectomy is the most effective available intervention but carries substantial operative mortality (~15–22%) and disease recurrence risk (~4–19%); medical therapy alone does not appear to alter the natural history of established fibrotic disease (per the negative prednisolone RCT).

Treatment strategy/algorithm: Stage-dependent — acute eosinophilic myocarditis phase (if captured) may warrant corticosteroids ± eosinophil-targeted therapy (imatinib if FIP1L1-PDGFRA+, mepolizumab); established fibrotic-stage disease is managed with heart-failure pharmacotherapy and anticoagulation, escalating to endocardiectomy ± valve surgery for NYHA III/IV symptoms refractory to medical therapy; heart transplantation is reserved for exceptional cases.

Sources: - The safety and efficacy of prednisolone in preventing reaccumulation of ascites among EMF patients in Uganda (PMC4678569) - In-Depth Review of Loeffler Endocarditis (PMC10984210) - Case report on heart transplantation in endomyocardial fibrosis (PMC12046388) - Successful Heart Transplantation for Unreversible EMF Related to FIP1L1-PDGFRA CEL - Endomyocardial Fibrosis Treatment & Management (Medscape)

13. Prevention

Primary prevention: No disease-specific primary prevention strategy is established. Given the etiologic hypotheses, plausible (but not formally trial-proven for EMF-incidence reduction) primary-prevention levers include: - Population deworming and helminth/schistosomiasis control programs in endemic regions. - Nutritional interventions addressing protein-calorie and micronutrient (magnesium) deficiency and reducing dependence on inadequately processed cassava. - Malaria control. - Poverty alleviation (the strongest and most consistently identified structural risk factor).

Notably, no clinical trial has directly tested whether these interventions reduce EMF incidence; the rationale is inferential from the epidemiologic/mechanistic associations discussed above.

Secondary prevention (early detection): Community echocardiographic screening, as piloted in the Mozambique population study, could theoretically identify subclinical/mild disease (the ~77% of prevalent cases who were asymptomatic in that study) for closer monitoring, though no screening program has been operationalized at scale, and there is no proven early intervention that alters the natural history once fibrosis is detected.

Tertiary prevention: Standard heart-failure medical management, anticoagulation to prevent thromboembolic complications, and timely surgical referral (endocardiectomy ± valve surgery) before end-stage/refractory heart failure develops.

Immunization: Not applicable — no vaccine-preventable causal agent has been established.

Genetic counseling: Not applicable in the conventional Mendelian sense given the complex/multifactorial and non-Mendelian inheritance pattern; family history (given documented familial clustering) may still warrant clinical/echocardiographic surveillance of relatives in high-risk families, though this is not a formalized guideline recommendation identified in the literature.

Public health interventions: Improved sanitation and vector/parasite control (reducing helminth and malarial burden), nutritional support programs, and expanded access to echocardiography in endemic primary-care settings are the most plausible public-health levers, consistent with the observed decline in hospital-based EMF incidence attributed generally to "improving healthcare and living standards."

Sources: As cited above (PMID: 18301727; PMC12701864/PMID: 41399600; PMC4239813).

14. Other Species / Natural Disease

Taxonomy: Naturally occurring EMF as described here is a human disease; there is no well-established veterinary/naturally occurring analog reported in companion animals or wildlife in the literature reviewed.

Experimental (induced, non-natural) models: - Cercopithecus aethiops (African green monkey; NCBI Taxon ID needed/verify) fed a cassava-based, severe-protein-deficient diet developed cardiac lesions resembling human EMF, while banana-fed controls did not — supporting the cassava/protein-deficiency causal hypothesis (cited in PMID: 18301727). - Plantain-feeding experiments in guinea pigs, rats, and Patas monkeys (testing the serotonin hypothesis) failed to reproduce EMF lesions, effectively refuting that hypothesis (PMID: 18301727).

Comparative biology: No dedicated comparative pathology or evolutionary-conservation literature on EMF mechanisms across species was identified. The eosinophil-mediated cardiotoxicity mechanism (ECP/MBP-driven endothelial injury and coagulation activation) is presumed broadly conserved across mammals based on general eosinophil biology, but this has not been formally studied in the specific context of EMF model development.

Zoonotic potential / transmission: Not applicable — EMF is not an infectious/transmissible disease itself, though proposed infectious co-factors (helminths, Plasmodium) are separately zoonotic/vector-borne in their own right.

Note on a distinct but nomenclature-adjacent condition: Endocardial fibroelastosis (EFE, OMIM:226000) — a different, largely pediatric/congenital disease — has documented animal models (e.g., distention of the immature left ventricle inducing EFE-like lesions, PMC4433646) and, in some human cases, a ciliopathy-gene basis (e.g., in Alström syndrome, PMC8541947). These EFE-specific models and genetic findings should not be conflated with tropical/idiopathic EMF model organism data.

Sources: - Endomyocardial Fibrosis: Still a Mystery after 60 Years (PMID: 18301727) - Distention of the Immature Left Ventricle Triggers Development of Endocardial Fibroelastosis (PMC4433646) (EFE model — distinct disease, included for disambiguation only)

15. Model Organisms

Summary: Model-organism research specific to tropical/idiopathic EMF is sparse and largely historical, reflecting both the disease's endemic-region concentration (limiting research infrastructure) and the field's general stagnation after the 1980s (publication volume "declined dramatically post-1980s," peaking "prior to the diffusion of echocardiography in much of the tropics," per PMID: 18301727).

Genetic/induced models identified: - Cassava/protein-deprivation model (non-human primate): Cercopithecus aethiops fed uncooked cassava under severe protein restriction — produced cardiac histopathology resembling human EMF, plus hepatic changes resembling tropical splenomegaly syndrome, supporting a shared cassava/malnutrition etiology for both conditions. This model did partially recapitulate the human phenotype but has not been followed up with modern molecular characterization. - Serotonin/plantain hypothesis models (guinea pig, rat, Patas monkey): Failed to reproduce EMF lesions — a negative model result that helped rule out the serotonin-metabolite hypothesis. - No genetically engineered (knockout/knock-in/transgenic/conditional/humanized) mouse or other rodent model of EMF was identified in this search — a clear gap, likely attributable to the absence of an established causal gene to target. - FIP1L1-PDGFRA / hypereosinophilic syndrome models: General HES/eosinophilic-cardiotoxicity models (e.g., IL-5 transgenic or eosinophil-adoptive-transfer mouse models used in broader eosinophilic-disease research) exist in the eosinophil biology literature but were not specifically identified as validated EMF models in this search; they represent the most plausible near-term modeling avenue given the shared mechanism with Löffler endocarditis.

Model limitations: No model captures the full multifactorial human EMF phenotype (chronic malnutrition + parasitic/immune exposure + genetic susceptibility + years-long fibrotic evolution); the primate cassava model is the closest histopathologic recapitulation identified but is decades old, ethically and logistically difficult to repeat with modern techniques, and was not molecularly characterized by contemporary standards (no transcriptomic/proteomic follow-up reported).

Applications: Existing models have been used primarily to test/refute specific etiologic hypotheses (cassava/protein deficiency: supported; serotonin/plantain: refuted) rather than to dissect molecular pathogenesis or screen therapeutics — an important direction the 2025 Nature Reviews Cardiology review (Mocumbi et al., DOI: 10.1038/s41569-025-01138-x) explicitly flags as a priority for identifying preclinical biomarkers and novel therapeutic targets, though full-text access to that review's specific model-organism recommendations could not be retrieved in this session (paywalled).

Resources: No dedicated EMF model-organism database or repository was identified (unlike diseases with established genetic models catalogued in MGI/IMPC/ZFIN); this itself is a notable research-infrastructure gap for EMF.

Sources: - Endomyocardial Fibrosis: Still a Mystery after 60 Years (PMID: 18301727) - Endomyocardial fibrosis: recent advances and future therapeutic targets (Nat Rev Cardiol 2025) — abstract/metadata only accessible (paywalled); Mocumbi et al., Nat Rev Cardiol 2025;22(8):564–576.

Summary of Key Knowledge Gaps (for curation planning)

No established causal gene — EMF is genetically complex, not monogenic; avoid asserting a causal gene/OMIM entry (OMIM:226000 belongs to the distinct disease EFE, not EMF).
HLA associations (HLA-B*58, HLA-A*02:02) are single-study, population-specific, and unreplicated — should be curated as SUSCEPTIBILITY-level evidence with appropriately guarded confidence, not as established risk alleles.
The etiologic model remains a multifactorial hypothesis, not a proven causal chain — the eosinophil/Löffler-equivalence mechanism has the strongest histopathologic support, but "no single proposed factor can explain the occurrence of EMF worldwide" per the primary review literature.
No RCT-proven disease-modifying medical therapy exists — the one identified RCT (prednisolone for ascites) was negative; this is important, citable negative evidence.
FIP1L1-PDGFRA/imatinib pathway is a distinct, actionable, but etiologically separate subset (clonal hypereosinophilic syndrome/Löffler-variant EMF) — should likely be modeled as a related but distinct causal branch/subtype rather than conflated with classic nutritional/parasitic tropical EMF.
Modern omics data (transcriptomic, proteomic, single-cell) for human EMF cardiac tissue are essentially absent from the literature surveyed — a genuine research and knowledge-base gap.
Global prevalence/burden estimates (e.g., "~12 million") are poorly sourced/extrapolated and should be cited cautiously with the underlying Mozambique 19.8% population-prevalence study (PMID: 18596273) as the strongest primary anchor.
Full text of the most current comprehensive review (Mocumbi et al., Nat Rev Cardiol 2025) was paywalled and not fully accessible in this session — recommend independent retrieval for the most up-to-date synthesis before finalizing a knowledge-base entry.

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Pathophysiology

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Endomyocardial Fibrosis (EMF): Comprehensive Disease Research Report

1. Disease Information

2. Etiology

Disease causal factors — historically proposed hypotheses

Risk factors

3. Phenotypes

Cardiac signs and symptoms

Systemic/constitutional signs

Laboratory abnormalities

Phenotype characteristics

Quality of life impact

4. Genetic/Molecular Information

5. Environmental Information

6. Mechanism / Pathophysiology

Causal chain overview (from trigger to clinical manifestation)

Molecular pathways

Cellular processes

Protein dysfunction / biochemical abnormalities

Immune system involvement

Tissue damage mechanisms

Molecular profiling

Suggested ontology terms (verify before curation)

7. Anatomical Structures Affected

8. Temporal Development

9. Inheritance and Population

10. Diagnostics

11. Outcome/Prognosis

12. Treatment

13. Prevention

14. Other Species / Natural Disease

15. Model Organisms

Summary of Key Knowledge Gaps (for curation planning)