Rheumatic Heart Disease

Complex MONDO:0006955 Pathograph 19 Show in embeddings browser acquired valvular heart disease post-infectious autoimmune disease

Permanent valvular heart damage following one or more episodes of acute rheumatic fever, itself a delayed non-suppurative autoimmune sequela of group A streptococcal infection in a genetically susceptible host. The organism is never found in the damaged valve, so this is an infection-triggered autoimmune disease rather than an infection of the valve. That distinction separates it from infective endocarditis and determines that effective treatment is prophylaxis against reinfection rather than treatment of the heart. It remains the leading cause of acquired heart disease in children worldwide and causes the highest disability burden of any cardiovascular disease in 10 to 14 year olds, a distribution that follows poverty and crowding rather than any biological gradient.

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1
Inheritance
11
Pathophys.
11
Phenotypes
4
Gaps
19
Pathograph
2
Genes
6
Medical Actions
3
Differentials
1
Models
1
Deep Research
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Classifications

Harrison's Part
CARDIOVASCULAR
👪

Inheritance

1
Polygenic susceptibility HP:0010982
Not Mendelian. Susceptibility is polygenic, dominated by HLA class II and class III variation with contributions from the immunoglobulin heavy chain locus, and it acts only in combination with the environmental exposure. No genetic test is used in management.
Polygenic inheritance
Show evidence (1 reference)
PMID:32488134 SUPPORT Human Clinical
"These findings suggest the class III region is a key determinant of RHD susceptibility offering important new insight into pathogenesis while partly explaining the inconsistency of earlier reports."
Establishes the disease as a susceptibility trait mapped by population association rather than by Mendelian segregation, and notes that earlier reports were inconsistent, which is why this entry curates the inheritance as polygenic rather than naming specific risk alleles.
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Discussions and Knowledge Gaps

4
Is cardiac myosin the initial target of the cross-reactive immune response, or is it reached only after extracellular proteins have been damaged first?
CONTROVERSY OPEN initial_autoantigen_disputed
Attached to
pathophysiology#Molecular mimicry and cross-reactive immune priming
The textbook account, well supported by sequence mimicry and by animal models immunised with M protein and cardiac myosin, is that cardiac myosin is the cross-reactive target. The objection is mechanical rather than immunological. Myosin is intracellular and therefore not accessible to circulating antibody in an intact cell, so it is an odd candidate for the first thing an antibody binds. The alternative proposes that extracellular and cell-surface proteins are hit first, namely laminin, collagen IV, the coxsackievirus-adenovirus receptor, and the beta-1 adrenergic receptor, with the response drifting to myosin and actin only after cells are damaged and their contents exposed. This is not merely a question of ordering. If the initial targets are extracellular, then those are the antigens a vaccine or a tolerising therapy would have to account for, and the animal models that immunise directly with myosin may be reproducing a late stage of the disease while skipping the step that actually initiates it.
Proposed experiments
Serial autoantibody specificity profiling from streptococcal pharyngitis through acute rheumatic fever
exp_serial_autoantibody_profiling
Serially profile antibody specificity against laminin, collagen IV, the coxsackievirus-adenovirus receptor, the beta-1 adrenergic receptor, and cardiac myosin in a prospective cohort followed from streptococcal pharyngitis through any subsequent acute rheumatic fever. If extracellular targets are struck first, antibodies against them should precede anti-myosin antibodies rather than appear alongside them.
Show evidence (3 references)
PMID:25191648 SUPPORT Computational
"But myosin and actin are immunologically inaccessible and unlikely initial targets. Extracellular cardiac proteins that mimic GAS and CX would be more likely."
States the objection to the canonical model in its own terms, along with the reasoning behind the alternative.
PMID:25191648 SUPPORT Computational
"Epitope drift shifts the immune response to myosin and actin after cardiomyocytes become damaged."
The proposed reconciliation, in which both models describe different stages. PARTIAL because it arises from sequence-similarity searching rather than from a demonstrated sequence of events in patients.
PMID:16455580 SUPPORT Human Clinical
"the a-helical coiled-coil streptococcal M protein structurally mimic cardiac myosin in the human disease, rheumatic carditis, and in animal models immunized with streptococcal M protein and cardiac myosin"
The canonical position, which this discussion weighs against the alternative rather than discards.
Given that immune-mediated valvulitis is what destroys the valve, why does anti-inflammatory treatment during the acute episode fail to reduce valve damage, and is that negative result real?
OPEN QUESTION OPEN anti_inflammatory_treatment_does_not_protect_the_valve
Attached to
pathophysiology#Acute valvulitis with Aschoff body formation pathophysiology#Chronic valve fibrosis, commissural fusion, and calcification
Every step in this entry's causal chain predicts that suppressing acute inflammation should preserve the valve, and the trial evidence does not show it. There are at least three readings and they carry different consequences. The damage may already be done by the time carditis is clinically apparent, in which case the intervention is simply too late and earlier detection is the answer. The agents tested may be too weak or wrongly targeted, in which case a modern trial with better drugs is warranted. Or the trials themselves, six of eight conducted between 1950 and 1965 with substantial risk of bias, may simply be incapable of detecting an effect that exists. The reviewers call for new trials, which is a statement that they regard the question as open rather than answered. This matters because in the absence of a valve-protective therapy the entire burden of preventing this disease falls on prophylaxis and adherence.
Proposed experiments
Randomised trial of a modern immunomodulator in echocardiographically confirmed acute carditis with valve morphology as the endpoint
exp_modern_anti_inflammatory_trial
Randomise patients with echocardiographically confirmed acute carditis to a modern anti-inflammatory or immunomodulatory agent or placebo, with valve morphology at two years as the primary endpoint rather than a clinical composite. The decision criterion is whether valve outcome differs. A symptomatic benefit without a structural one would confirm the existing picture rather than change it.
Show evidence (2 references)
PMID:26017576 SUPPORT Human Clinical
"Little evidence of benefit was found when corticosteroids or intravenous immunoglobulins were used to reduce the risk of heart valve lesions in patients with acute rheumatic fever."
The negative finding that this discussion exists to explain.
PMID:26017576 SUPPORT Human Clinical
"In addition, risk of bias was substantial, so results should be viewed with caution."
PARTIAL. The reviewers' own warning about their result, which is what makes this an open question rather than a settled negative.
Can a group A streptococcal vaccine be developed that prevents this disease without provoking the very cross-reactivity that causes it?
KNOWLEDGE GAP OPEN gas_vaccine_as_the_only_route_to_elimination
Attached to
pathophysiology#Group A streptococcal infection in a susceptible host pathophysiology#Molecular mimicry and cross-reactive immune priming
Every intervention curated in this entry is downstream of an infection that has already happened, and the one that works depends on an injection regimen people cannot complete. A vaccine is the only intervention that would remove the trigger at population scale, and the World Health Organization has published a formal development roadmap and preferred product characteristics for one. The difficulty is specific to this disease and follows directly from its mechanism. The immunodominant streptococcal antigens are precisely the ones that cross-react with cardiac tissue, so a vaccine that raises antibodies against M protein risks inducing the autoimmunity it is meant to prevent. Current approaches try to route around this, for instance by targeting the L-rhamnose backbone of the group A carbohydrate, chosen because the rhamnose biosynthesis pathway is absent from mammalian cells and so cannot be mimicked. Whether that avoids cross-reactivity in humans rather than in test animals is unresolved.
Proposed experiments
Human cardiac tissue cross-reactivity screening of candidate group A streptococcal vaccine antisera
exp_gas_vaccine_cross_reactivity_human
Screen antisera raised by candidate vaccine antigens against a panel of human cardiac and valvular proteins, including cardiac myosin, laminin, collagen IV, and the beta-1 adrenergic receptor, before any efficacy trial. The decision criterion is whether cross-reactivity is detectable against human rather than animal tissue, since the animal result is what current candidates rest on and is not the relevant test.
Show evidence (4 references)
PMID:30624673 SUPPORT Human Clinical
"Impediments related to antigen diversity, safety concerns, and the difficulty to establish vaccine efficacy against rheumatic heart disease are discussed."
Names the three obstacles to a vaccine, including the specific difficulty of demonstrating efficacy against this disease, which is the substance of this discussion rather than the existence of a roadmap.
PMID:30624673 SUPPORT Human Clinical
"Demonstration of vaccine efficacy against pharyngitis and skin infections constitutes a key near-term strategic goal."
States the near-term strategy, which is itself informative. Efficacy is to be shown against the infections rather than against this disease, because the rheumatic endpoint is too rare and too delayed to power a trial on directly.
PMID:39959434 SUPPORT Model Organism
"The L-Rhamnose-based vaccine was chosen due to the absence of the Rhamnose biosynthesis pathway in mammalian cells including humans thus this molecule is not found in any body tissue."
States the design rationale for avoiding cross-reactivity, namely selecting an antigen with no mammalian counterpart to mimic.
+ 1 more reference
Can secondary prophylaxis be delivered in a form that people will actually complete, and would doing so close the gap between its efficacy and its real-world effect?
KNOWLEDGE GAP OPEN prophylaxis_burden_is_the_limiting_factor
Attached to
treatments#Benzathine penicillin G secondary prophylaxis
This disease is unusual in having a cheap intervention of established efficacy that reliably fails in practice for reasons that are not biological. Benzathine penicillin requires a painful deep intramuscular injection every three to four weeks for at least five years, typically in adolescents who feel well, in settings with limited health infrastructure. Adherence is correspondingly poor, and recurrence follows, which is what converts survivable valve disease into fatal valve disease. The gap between efficacy and effectiveness here is arguably the single largest determinant of the global burden, and it is a pharmacological and delivery problem rather than a mechanistic one. A subcutaneous high-dose formulation permitting less frequent dosing is in early trials.
Proposed experiments
Long-acting subcutaneous benzathine penicillin versus monthly intramuscular dosing with course completion as a co-primary endpoint
exp_long_acting_prophylaxis_outcomes
Randomise patients to a long-acting subcutaneous benzathine penicillin formulation or to standard monthly intramuscular dosing, with completion of the prophylaxis course and recurrence of acute rheumatic fever as co-primary endpoints. The point is to test whether removing the delivery burden closes the efficacy-effectiveness gap, so adherence has to be an endpoint and not a covariate.
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Pathophysiology

11
Group A streptococcal infection in a susceptible host
Pharyngeal infection with Streptococcus pyogenes is the initiating event. Skin infection is an increasingly recognised alternative portal in high-burden tropical settings. Susceptibility is conferred largely by HLA class II genotype, which determines which streptococcal and self peptides are presented to CD4-positive T cells, so the same exposure produces disease in some hosts and not others.
Downstream
Molecular mimicry and cross-reactive immune priming Antigens of the organism prime an immune response that does not distinguish them from host cardiac and connective tissue proteins.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"Acute rheumatic fever (ARF) is an autoimmune disease caused by group A streptococcal infection."
States the causal relationship between the streptococcal infection and the autoimmune illness that follows.
Molecular mimicry and cross-reactive immune priming
The group A carbohydrate epitope N-acetylglucosamine and the alpha-helical coiled-coil M protein structurally resemble human cardiac myosin and connective tissue proteins closely enough that antibodies and T cells raised against the organism bind host tissue. Which host protein is struck first is genuinely disputed and is curated as a controversy rather than as settled fact. The long-standing answer is cardiac myosin, but myosin is intracellular and therefore hard to reach, which motivates an alternative in which extracellular proteins are hit first.
inflammatory response to antigenic stimulus GO:0002437 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response to antigenic stimulus (GO:0002437). GO:0002437 is a biological process from the Gene Ontology. ↑ INCREASED
Experimental models
Lewis rat autoimmune valvulitis model OTHER Immunisation with M protein or cardiac myosin reproduces the cross-reactive response.
Downstream
Cross-reactive antibody binding and valve endothelial activation Cross-reactive antibody binds the valve surface, whichever host protein it recognises first.
Show evidence (2 references)
PMID:16455580 SUPPORT Human Clinical
"Molecular mimicry is a hallmark of the pathogenesis of rheumatic fever where the streptococcal group A carbohydrate epitope, N-acetyl glucosamine, and the a-helical coiled-coil streptococcal M protein structurally mimic cardiac myosin in the human disease, rheumatic carditis"
Names both mimicking epitopes and the canonical host target, which is the claim this node rests on.
PMID:16455580 SUPPORT Human Clinical
"Both B- and T-cell responses are involved in the process, and evidence for the hypotheses of molecular mimicry and epitope spreading are reviewed."
Establishes that both arms of adaptive immunity participate, which is why this entry curates a separate antibody node and T cell node rather than one combined immune node.
Cross-reactive antibody binding and valve endothelial activation
Cross-reactive antibody binds valve endothelium and upregulates VCAM-1, converting the valve surface from a quiescent lining into an adhesive one. This is the step that recruits the cellular infiltrate; antibody alone does not destroy the valve.
valve endothelial cell CL:0000115 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves valve endothelial cell, annotated with endothelial cell (CL:0000115). CL:0000115 is a cell type from the Cell Ontology.
mitral valve UBERON:0002135 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitral valve (UBERON:0002135). UBERON:0002135 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
CD4-positive T cell infiltration of the valve Adhesion molecule upregulation permits lymphocyte recruitment into a normally avascular tissue.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"The purpose of this mini review is to delineate the etiology and pathophysiological mechanisms underlying ARF and RHD."
PARTIAL. The review covers this step, but its abstract states scope rather than the VCAM-1 finding itself, so this citation locates the mechanism in the literature without evidencing the specific adhesion molecule claim.
CD4-positive T cell infiltration of the valve
CD4-positive T lymphocytes showing degenerate, cross-reactive antigen recognition infiltrate valve tissue and myocardium and are considered the prime effectors of valve destruction. Epitope spreading broadens the response with each recurrence, which is the mechanistic reason a second episode of rheumatic fever damages the valve more than the first, and why prophylaxis against reinfection is the whole of secondary prevention.
CD4-positive T cell CL:0000624 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves CD4-positive T cell, annotated with CD4-positive, alpha-beta T cell (CL:0000624). CL:0000624 is a cell type from the Cell Ontology.
T cell mediated immunity GO:0002456 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased T cell mediated immunity (GO:0002456). GO:0002456 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Acute valvulitis with Aschoff body formation Sustained lymphocytic and macrophage infiltration organises into the characteristic lesion.
Show evidence (1 reference)
PMID:16455580 SUPPORT Human Clinical
"Recent studies have unraveled the potential pathogenic mechanisms by which the immune response against the group A streptococcus attacks the rheumatic valve leading to chronic rheumatic heart disease."
States that the immune response attacks the valve and that this is what produces the chronic disease, which is the causal role this node occupies.
Acute valvulitis with Aschoff body formation
The histological signature of active carditis, consisting of granulomatous foci of central fibrinoid necrosis ringed by lymphocytes, plasma cells, and macrophages, including the Anitschkow cells whose linear chromatin gives them their caterpillar appearance. The Aschoff body is a pathological structure formed de novo and so is conceptually an Xogenesis lesion, but it is deliberately not curated as conforming to the granuloma_formation module. That module models containment of an indigestible persistent stimulus by macrophage fusion, and here there is no organism in the tissue to contain.
macrophage CL:0000235 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves macrophage (CL:0000235). CL:0000235 is a cell type from the Cell Ontology.
mitral valve UBERON:0002135 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitral valve (UBERON:0002135). UBERON:0002135 is an anatomical location from the Uberon multi-species anatomy ontology.
Experimental models
Lewis rat autoimmune valvulitis model OTHER The model develops valvulitis, the acute lesion of this disease.
Downstream
Chronic valve fibrosis, commissural fusion, and calcification Repeated or persistent inflammation converts reversible valvulitis into fixed scar.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"Recurrent episodes of ARF can lead to rheumatic heart disease (RHD)"
PARTIAL. Supports the acute to chronic transition this node sits on, but does not itself describe the Aschoff body, which is drawn from textbook histopathology and is not separately evidenced here.
Chronic valve fibrosis, commissural fusion, and calcification
Leaflet thickening, neovascularisation of a normally avascular tissue, fusion of the commissures, and dystrophic calcification convert inflammation into fixed stenosis, regurgitation, or both. This is the point of no return, since everything upstream is in principle reversible and nothing from here on is. The mitral valve is affected most often and most severely, then the aortic, an asymmetry conventionally attributed to the higher shear stress on left-sided valves.
valve interstitial cell CL:4030032 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves valve interstitial cell (CL:4030032). CL:4030032 is a cell type from the Cell Ontology.
extracellular matrix organization GO:0030198 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased extracellular matrix organization (GO:0030198). GO:0030198 is a biological process from the Gene Ontology. ↑ INCREASED
mitral valve UBERON:0002135 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitral valve (UBERON:0002135). UBERON:0002135 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Valvular stenosis and regurgitation with hemodynamic overload Fixed structural valve deformity imposes a pressure or volume load on the chambers upstream.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"Recurrent episodes of ARF can lead to rheumatic heart disease (RHD), which is the leading cause of cardiovascular mortality in children worldwide, especially in low- and middle-income countries."
States that the recurrent acute episodes produce the chronic disease this node represents, and names its consequence.
Valvular stenosis and regurgitation with hemodynamic overload
Mitral regurgitation appears first, mitral stenosis later as leaflets thicken and commissures fuse. The resulting left atrial enlargement, pulmonary venous congestion, and ventricular volume or pressure overload account for essentially all the downstream clinical disease.
Downstream
Atrial fibrillation and cardioembolic risk Left atrial enlargement from mitral disease creates the substrate for atrial fibrillation.
Congestive heart failure Chronic volume or pressure overload culminates in ventricular failure.
Pulmonary venous congestion and pulmonary hypertension Mitral stenosis raises left atrial pressure, which is transmitted backwards into the pulmonary venous circulation.
Pulmonary venous congestion and pulmonary hypertension
Sustained elevation of left atrial pressure in mitral stenosis is transmitted back through the pulmonary veins, and chronic passive congestion eventually produces reactive remodelling of the pulmonary arterioles. This is post-capillary pulmonary hypertension arising from a mechanical upstream cause, so conformance is declared at the remodelling node only and not at the module's endothelial and BMPR2 trigger nodes, which model a primary pulmonary arteriopathy. The consequence is right ventricular pressure loading, which is how a left-sided valve lesion ends in right heart failure.
Downstream
Right heart failure Chronically raised pulmonary vascular resistance loads the right ventricle.
Right heart failure
Raised jugular venous pressure, hepatic congestion, ascites, and peripheral oedema, arising from right ventricular pressure loading rather than from any right-sided valve lesion. Curated separately from left-sided congestive failure because the mechanism and the clinical picture differ.
Atrial fibrillation and cardioembolic risk
Atrial fibrillation here is structural, arising from left atrial enlargement, and is deliberately not curated as conforming to cardiac_ion_channel_repolarization. That module models a primary channelopathy in a structurally normal heart, which is the opposite of the situation here. The distinction is not academic, because it is why this population needs a vitamin K antagonist rather than a direct oral anticoagulant, a question settled by trial and against expectation.
Downstream
Congestive heart failure Loss of atrial contribution and rate irregularity worsen an already loaded ventricle.
Show evidence (1 reference)
PMID:36036525 SUPPORT Human Clinical
"Among patients with rheumatic heart disease-associated atrial fibrillation, vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy, without a higher rate of bleeding."
The INVICTUS result, which establishes that this form of atrial fibrillation behaves differently from nonvalvular atrial fibrillation and is the strongest evidence that it should be modelled as a distinct structural entity.
Congestive heart failure
The usual presenting syndrome, because chronic rheumatic heart disease is frequently silent until it decompensates. That latency is what motivates echocardiographic screening programmes in endemic populations.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"which is the leading cause of cardiovascular mortality in children worldwide"
PARTIAL. Establishes that the disease is lethal but does not name heart failure as the mechanism of death.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Rheumatic Heart Disease Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

11
Cardiovascular 4
Aortic regurgitation HP:0001659 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aortic regurgitation (HP:0001659). HP:0001659 is a phenotype from the Human Phenotype Ontology.
Atrial fibrillation HP:0005110 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atrial fibrillation (HP:0005110). HP:0005110 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36036525 SUPPORT Human Clinical
"Of 4565 enrolled patients, 4531 were included in the final analysis. The mean age of the patients was 50.5 years, and 72.3% were women."
A trial of 4531 patients defined by rheumatic heart disease with atrial fibrillation establishes the association at scale, and incidentally documents the striking female predominance of this disease.
Congestive heart failure HP:0001635 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congestive heart failure (HP:0001635). HP:0001635 is a phenotype from the Human Phenotype Ontology.
Stroke HP:0001297 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Stroke (HP:0001297). HP:0001297 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36036525 SUPPORT Human Clinical
"vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy"
PARTIAL. Stroke is a component of the composite endpoint rather than separately reported in this abstract, so this supports the embolic risk without quantifying stroke alone.
Integument 1
Subcutaneous nodules HP:0001482 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Subcutaneous nodule (HP:0001482). HP:0001482 is a phenotype from the Human Phenotype Ontology.
Metabolism 1
Fever HP:0001945 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fever (HP:0001945), qualified as temporality acute. HP:0001945 is a phenotype from the Human Phenotype Ontology.
Temporal: ACUTE
Musculoskeletal 1
Migratory polyarthritis HP:0001369 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Arthritis (HP:0001369), qualified as temporality acute. HP:0001369 is a phenotype from the Human Phenotype Ontology.
Temporal: ACUTE
Nervous System 1
Sydenham chorea HP:0002072 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Chorea (HP:0002072). HP:0002072 is a phenotype from the Human Phenotype Ontology.
Other 3
Mitral regurgitation HP:0001653 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mitral regurgitation (HP:0001653). HP:0001653 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22371105 SUPPORT Human Clinical
"Systematic differences in the reporting of and diagnostic approach to RHD exist, reflecting differences in local experience and disease patterns."
PARTIAL. Establishes that the diagnostic approach to these valvular lesions needed standardising, which is context for the lesion rather than evidence of its frequency; the cached abstract does not rank the valve lesions.
Mitral stenosis HP:0001718 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mitral stenosis (HP:0001718). HP:0001718 is a phenotype from the Human Phenotype Ontology.
Post-capillary pulmonary hypertension HP:0033635 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Post-capillary pulmonary hypertension (HP:0033635). HP:0033635 is a phenotype from the Human Phenotype Ontology.
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Genetic Associations

2
HLA-DQB1
Gene: HLA-DQB1 hgnc:4944 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is HLA-DQB1 (hgnc:4944). hgnc:4944 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE
Show evidence (1 reference)
PMID:32488134 SUPPORT Human Clinical
"The second and third strongest signals were found in the class I (HLA-B, rs3819306, P = 1.91×10−7) and class II (HLA-DQB1, rs28724238, P = 7.77×10−7) regions, respectively."
Locates the class II signal at HLA-DQB1 specifically. PARTIAL because at P = 7.77 x 10 to the minus 7 it falls short of genome-wide significance and ranks third in this study, so it supports a contributory role rather than an established one.
HLA-DRB1
Gene: HLA-DRB1 hgnc:4948 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is HLA-DRB1 (hgnc:4948). hgnc:4948 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SUSCEPTIBILITY variant_origin: GERMLINE
Show evidence (1 reference)
PMID:24581333 SUPPORT Human Clinical
"This study compares the frequency of HLA class II DR alleles between RHD cases and normal controls in Uganda."
States the design that produced the HLA-DR association, in a sub-Saharan African population where the disease burden is high.
💊

Medical Actions

6
Benzathine penicillin G secondary prophylaxis
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
The cornerstone of management, and the only intervention that alters the natural history. It works by preventing reinfection and therefore recurrence, not by treating the heart at all. It is given as a deep intramuscular injection every three to four weeks for a minimum of five years, often to age 21 or for ten years after the episode. The burden of that regimen, monthly painful injections in adolescents who feel well, is the principal reason real-world adherence is poor, and adherence rather than efficacy is the limiting factor.
Mechanism Target:
INHIBITS Group A streptococcal infection in a susceptible host — Prophylaxis acts on the initiating infection, upstream of every immunological step in this entry. Nothing downstream of the valve scar is reversible, which is why the only effective point of attack is the trigger.
Show evidence (1 reference)
PMID:15927077 SUPPORT Human Clinical
"Fixed effects, meta-analysis revealed an overall protective effect for the use of antibiotics against acute rheumatic fever of 70% (RR = 0.32; 95% CI = 0.21-0.48)."
Quantifies the protective effect of treating the streptococcal infection on the incidence of rheumatic fever, which is the causal link this treatment edge asserts.
Show evidence (2 references)
PMID:15927077 SUPPORT Human Clinical
"Antibiotics appear to be effective in reducing the incidence of acute rheumatic fever following an episode of suspected GAS pharyngitis. This effect may be achieved at relatively low cost if a single intramuscular penicillin injection is administered."
The authors' conclusion, including the cost point that makes this the intervention of choice in the settings where the disease actually occurs.
PMID:15927077 SUPPORT Human Clinical
"All of the included trials were conducted during the period of 1950 and 1961 and in 8 of the 10 trials the study population consisted of young adult males living on United States military bases."
PARTIAL, and an important qualification. The evidence base for the central preventive intervention is seventy-year-old trials in young American servicemen, a population with almost nothing in common with the children in whom the disease now occurs.
Anti-inflammatory therapy for acute carditis
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: aspirin CHEBI:15365 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses aspirin, annotated with acetylsalicylic acid (CHEBI:15365). CHEBI:15365 is a therapeutic agent from Chemical Entities of Biological Interest.
Aspirin or corticosteroids are given for symptomatic relief of the acute episode. They do not protect the valve. This is curated because the negative result matters. The intuitive assumption is that suppressing the inflammation which is destroying the valve should preserve it, and the trial evidence does not support that. The evidence is old and at substantial risk of bias, so this is a failure to demonstrate benefit rather than a demonstration of futility.
Mechanism Target:
INHIBITS Acute valvulitis with Aschoff body formation — The rationale is suppression of the valvular inflammation before it becomes scar.
Show evidence (1 reference)
PMID:26017576 REFUTE Human Clinical
"Little evidence of benefit was found when corticosteroids or intravenous immunoglobulins were used to reduce the risk of heart valve lesions in patients with acute rheumatic fever."
Refutes the proposition that suppressing acute inflammation preserves the valve, which is the claim this treatment edge would otherwise assert.
Show evidence (2 references)
PMID:26017576 SUPPORT Human Clinical
"The antiquity of most of the trials restricted adequate statistical analysis of the data and acceptable assessment of clinical outcomes by current standards. In addition, risk of bias was substantial, so results should be viewed with caution."
The reviewers' own caveat, which is why this is curated as absence of demonstrated benefit rather than as established futility.
PMID:26017576 SUPPORT Human Clinical
"Six trials were conducted between 1950 and 1965; one was done in 1990 and the final study was published in 2001."
PARTIAL. Dates the evidence base, which is the substance of the caveat above.
Vitamin K antagonist anticoagulation
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: warfarin CHEBI:10033 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses warfarin (CHEBI:10033). CHEBI:10033 is a therapeutic agent from Chemical Entities of Biological Interest.
Warfarin, with a target INR of 2 to 3, for atrial fibrillation or a mechanical valve. This is one of the few places in modern cardiology where the older drug won a head-to-head trial. Direct oral anticoagulants are standard for nonvalvular atrial fibrillation, and in this population they were worse. That result is the practical payoff of modelling rheumatic atrial fibrillation as a structural rather than an electrical disease.
Mechanism Target:
INHIBITS Atrial fibrillation and cardioembolic risk — Anticoagulation addresses the thromboembolic consequence, not the arrhythmia or the valve.
Show evidence (1 reference)
PMID:36036525 SUPPORT Human Clinical
"vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy, without a higher rate of bleeding"
Establishes vitamin K antagonism as superior in this specific population, with no bleeding penalty.
Show evidence (1 reference)
PMID:36036525 SUPPORT Human Clinical
"Permanent discontinuation of trial medication was more common with rivaroxaban than with vitamin K antagonist therapy at all visits."
A secondary finding that complicates the simple reading of the result, since differential discontinuation is itself a candidate explanation for the difference in outcome.
Low-molecular-weight heparin anticoagulation in pregnancy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Pregnancy is the period of highest thromboembolic risk in a woman with a prosthetic valve, and it is also when warfarin cannot be used, because it crosses the placenta and is teratogenic in the first trimester. Low-molecular-weight heparin is the usual substitute and remains an off-label indication without an agreed regimen, which is a substantial evidence gap in a disease whose population is overwhelmingly young women. The modality is recorded as OTHER rather than SMALL_MOLECULE, since a low-molecular-weight heparin is a sulfated polysaccharide rather than a small molecule in the usual sense.
Mechanism Target:
INHIBITS Valvular stenosis and regurgitation with hemodynamic overload — The thromboembolic risk this addresses arises from the prosthetic valve implanted to treat the valvular lesion, so the edge is drawn to the valve node rather than to atrial fibrillation. The cited study is specifically about women with prosthetic valve replacement, and attributing it to the arrhythmia would misstate what was measured.
Show evidence (3 references)
PMID:35464573 SUPPORT Human Clinical
"In patients with rheumatic heart disease (RHD) and prosthetic valve replacement, the risk of thromboembolic complications is the highest during and immediately after pregnancy."
Establishes pregnancy as the period of peak thromboembolic risk in this population, which is why the anticoagulation question is acute here.
PMID:35464573 SUPPORT Human Clinical
"The use of low-molecular-weight heparin (LMWH) remains an off-label indication."
PARTIAL, and recorded because it is a limitation rather than a result. The standard of care in the highest-risk period of this disease rests on off-label use.
PMID:35464573 SUPPORT Human Clinical
"LMWH is both safe and effective in preventing major thromboembolic complications compared to other forms of anticoagulation used during pregnancy."
The efficacy finding itself, from what its authors describe as the largest retrospective series of anticoagulation options in this specific population. It is retrospective, which is why the off-label caveat above is retained alongside it.
Percutaneous balloon mitral valvuloplasty
Action: Therapeutic ProcedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Therapeutic Procedure (NCIT:C49236). NCIT:C49236 is a clinical intervention from the NCI Thesaurus. NCIT:C49236
Mechanical relief of rheumatic mitral stenosis in suitable valves, meaning those that are not calcified and not significantly regurgitant. It is less invasive and cheaper than surgery, which matters disproportionately in the settings where this disease actually occurs.
Mechanism Target:
BYPASSES Valvular stenosis and regurgitation with hemodynamic overload — Splitting the fused commissures relieves the obstruction without addressing the scar itself.
Mitral valve repair or replacement
Action: Surgical ProcedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Surgical Procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. NCIT:C15329
Required for advanced, calcified, or regurgitant disease. Repair outperforms replacement where anatomically feasible. Mechanical replacement commits a young patient to lifelong anticoagulation, with the accumulating risks of thromboembolism, haemorrhage, perivalvular leak, and prosthetic endocarditis, which is a heavy long-term cost in the adolescents and young adults who make up much of this population.
Mechanism Target:
BYPASSES Valvular stenosis and regurgitation with hemodynamic overload — Replacing or repairing the valve restores competent flow without reversing the disease process.
🌍

Environmental Factors

1
Household crowding and poverty
exposure to adverse socioeconomic factors ECTO:6000028 Environmental Conditions, Treatments and Exposures Ontology (ECTO) Relation: this environmental factor is this exposure This environmental factor is exposure to adverse socioeconomic factors, annotated with exposure to socioeconomic factors (ECTO:6000028). ECTO:6000028 is an exposure from the Environmental Conditions, Treatments and Exposures Ontology.
ECTO:6000028 (exposure to socioeconomic factors) is bound as the closest available term. It covers the poverty dimension but not household crowding, for which the exposure hierarchy has no term, so this entry's name is deliberately broader than its binding. An earlier version of this note said no term was bound; the binding was added afterwards, by the #8430 exposure-binding sweep, which did not revisit the note.
The dominant determinant of who develops this disease. Crowding drives streptococcal transmission, and poverty drives both untreated pharyngitis and failure of secondary prophylaxis. The geographic and Indigenous-population disparity in burden is explained by these factors rather than by any biological gradient, which is why this entry treats them as mechanism rather than as background.
Show evidence (1 reference)
PMID:15927077 SUPPORT Human Clinical
"Rheumatic fever continues to put a significant burden on the health of low socio-economic populations in low and middle-income countries despite the near disappearance of the disease in the developed world over the past century."
Establishes that the disease is concentrated in low socio-economic populations and has all but vanished from wealthy countries, which is the association this exposure entry asserts. PARTIAL because it reports where the disease occurs rather than measuring an effect of crowding or of poverty.
Mechanism Target:
PREDISPOSES Group A streptococcal infection in a susceptible host — Crowding raises the rate of streptococcal transmission and therefore of the initiating infection.
Show evidence (1 reference)
PMID:15927077 SUPPORT Human Clinical
"Rheumatic fever continues to put a significant burden on the health of low socio-economic populations in low and middle-income countries despite the near disappearance of the disease in the developed world over the past century."
Documents the socioeconomic concentration of the disease and its disappearance from wealthy countries, which is the strongest available evidence that the determinant is social rather than biological. PARTIAL because it is an observed distribution rather than a measured exposure effect.
🔬

Biochemical Markers

4
Anti-streptolysin O titre (INCREASED)
Anti-DNase B titre (INCREASED)
C-reactive protein (INCREASED)
Erythrocyte sedimentation rate (INCREASED)
🔬

Diagnosis

3
Echocardiography using World Heart Federation criteria
The central diagnostic modality for chronic disease, and the basis of screening for latent disease in endemic populations. The criteria classify findings as definite, borderline, or normal, and were written specifically to standardise detection of subclinical disease so that people can be enrolled in prophylaxis before they become symptomatic.
Show evidence (1 reference)
PMID:22371105 SUPPORT Human Clinical
"Over the past 5 years, the advent of echocardiographic screening for rheumatic heart disease (RHD) has revealed a higher RHD burden than previously thought."
States what echocardiographic screening actually established, namely that the burden is larger than clinical detection had suggested, which is the reason these criteria exist.
Evidence of antecedent streptococcal infection
Throat culture or rapid antigen testing for the acute infection, and anti-streptolysin O and anti-DNase B titres for antecedent infection. This is a mandatory element of the Jones criteria, not a supporting investigation, because the entire causal claim of the disease rests on a preceding streptococcal infection that has usually resolved by the time the patient presents.
Revised Jones criteria
The clinical diagnostic framework for the acute episode, revised in 2015 to stratify by population risk, to incorporate Doppler echocardiography for subclinical carditis, and to accept isolated chorea as presumptive disease. The risk stratification is unusual and worth noting, because the same findings mean different things depending on the local incidence, which is an explicit acknowledgement that pretest probability differs enormously between populations.
Show evidence (1 reference)
PMID:25908771 SUPPORT Human Clinical
"The goal of this statement was to review the historic Jones criteria used to diagnose acute rheumatic fever in the context of the current epidemiology of the disease and to update those criteria to also take into account recent evidence supporting the use of Doppler echocardiography in the..."
States the purpose of the revision and, specifically, the elevation of Doppler-detected carditis to a major manifestation, which is the substantive change this diagnostic entry describes.
📈

Progression

4
Acute rheumatic fever
The acute multisystem episode, typically at age five to fourteen, with carditis, migratory arthritis, chorea, and skin manifestations in varying combination. Valvulitis at this stage is in principle reversible.
Latent chronic valve disease
Often clinically silent for years while fibrosis progresses, which is the reason echocardiographic screening exists in endemic populations and the reason the disease is frequently first diagnosed at the point of decompensation.
Progression by severity at diagnosis
Severity at diagnosis is the dominant prognostic determinant, and the trajectories diverge sharply. Severe disease is close to a surgical diagnosis; mild disease is mostly stable but not benign, since a tenth still progress to severe.
Show evidence (2 references)
PMID:28255075 SUPPORT Human Clinical
"Of 96 (16.2%) patients with severe RHD at diagnosis, 50% had proceeded to valve surgery by 2 years, and 10% were dead within 6 years."
Quantifies the trajectory of severe disease at diagnosis with counted denominators from a register-based cohort of 591 patients.
PMID:28255075 SUPPORT Human Clinical
"Patients with mild RHD at diagnosis were the most stable, with 64% remaining mild after 10 years; however, 11.4% progressed to severe RHD and half of these required surgery."
Quantifies the mild-disease trajectory, including the minority who progress, which is what makes surveillance of mild disease worthwhile rather than reassuring.
Decompensation and surgery
Heart failure, atrial fibrillation with embolic risk, and the need for valve intervention. In the cohort above the prognosis of young Indigenous Australians with severe disease is described by its authors as bleak, with the explicit conclusion that only earlier detection and treatment will change it.
Show evidence (1 reference)
PMID:28255075 SUPPORT Human Clinical
"The prognosis of young Indigenous Australians diagnosed with severe RHD is bleak; interventions must focus on earlier detection and treatment if the observed natural history is to be improved."
The authors' own conclusion, which is also the argument for the screening programmes curated in the diagnosis section.
📊

Prevalence

1
Worldwide
Point Prevalence >1 in 1,000
Concentrated in low- and middle-income countries and in Indigenous populations of wealthy ones. The class here is deliberately coarse, because no cited source in this entry states a rate.
Show evidence (1 reference)
PMID:40276383 SUPPORT Human Clinical
"which is the leading cause of cardiovascular mortality in children worldwide, especially in low- and middle-income countries"
PARTIAL. Establishes the global burden and its distribution, but states a rank rather than a rate, so the prevalence class is coarse and no numeric figure is asserted.
🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Rheumatic Heart Disease:

Infective endocarditis
Overlapping Features The critical distinction, and it runs in both directions. Infective endocarditis is an infection of the valve requiring prolonged antimicrobial therapy, whereas rheumatic heart disease is an autoimmune sequela in which the organism is absent from the valve. The two are also linked, because a rheumatic valve is a substrate on which infective endocarditis subsequently develops.
Juvenile idiopathic arthritis
Overlapping Features Shares the migratory arthritis of the acute episode. The distinguishing features are streptococcal serology, the exquisite aspirin responsiveness, and the presence of carditis.
Nonvalvular atrial fibrillation
Overlapping Features Not a differential for the disease itself but for its management. Treating rheumatic atrial fibrillation as though it were nonvalvular leads to the choice of a direct oral anticoagulant, which the INVICTUS trial showed to be inferior here.
🧫

Experimental Models

1
Lewis rat autoimmune valvulitis model OTHER
The principal animal model, produced by immunising Lewis rats with streptococcal M protein or cardiac myosin. It reproduces the valvulitis and the cross-reactive immune response, which is what established molecular mimicry as more than an observation about sequence similarity. It is explicitly the subject of a published discussion of what a robust model of this disease would have to demonstrate, which is a fair signal that the existing models are not considered settled.
Organism
Norway rat NCBITaxon:10116 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in Norway rat, annotated with Rattus norvegicus (NCBITaxon:10116). NCBITaxon:10116 is an organism from the NCBI Taxonomy.
Publication
PMID:25414841
Pathograph links
Molecular mimicry and cross-reactive immune priming Immunisation with M protein or cardiac myosin reproduces the cross-reactive response.
Acute valvulitis with Aschoff body formation The model develops valvulitis, the acute lesion of this disease.
Show evidence (2 references)
PMID:25414841 SUPPORT Model Organism
"Antibody and T cell responses to recombinant GAS M protein (rM) and the subsequent interactions with cardiac tissue have been predominantly investigated using a rat autoimmune valvulitis model."
Names this model as the principal system used to study the antibody and T cell responses that this entry curates as separate mechanism nodes.
PMID:34026876 SUPPORT Model Organism
"Disease complications triggered by Group A streptococcal (GAS) infection are confined to human and determining the early events leading to pathology requires a robust animal model that reflects the hallmark features of the disease."
PARTIAL, and included precisely because it is a statement of inadequacy. The disease is confined to humans, and a paper arguing that a robust model is still required is itself evidence that the existing ones fall short.
{ }

Source YAML

click to show 
name: Rheumatic Heart Disease
creation_date: "2026-08-10T00:20:00Z"
category: Complex
disease_term:
  preferred_term: rheumatic heart disease
  term:
    id: MONDO:0006955
    label: rheumatic heart disease
description: >
  Permanent valvular heart damage following one or more episodes of acute rheumatic fever, itself
  a delayed non-suppurative autoimmune sequela of group A streptococcal infection in a genetically
  susceptible host. The organism is never found in the damaged valve, so this is an infection-triggered
  autoimmune disease rather than an infection of the valve. That distinction separates it from
  infective endocarditis and determines that effective treatment is prophylaxis against reinfection
  rather than treatment of the heart. It remains the leading cause of acquired heart disease in
  children worldwide and causes the highest disability burden of any cardiovascular disease in 10 to
  14 year olds, a distribution that follows poverty and crowding rather than any biological gradient.
parents:
- acquired valvular heart disease
- post-infectious autoimmune disease

classifications:
  harrisons_chapter:
  - classification_value: CARDIOVASCULAR
    notes: >-
      Curated as the chronic valvular disease. The acute rheumatic fever episode that causes it is a
      multisystem illness with joint, neurological, and cutaneous features that fall outside this
      chapter; those manifestations are curated here as phenotypes of the acute phase because they
      are what establishes the diagnosis, not because they are cardiac.

pathophysiology:
- name: Group A streptococcal infection in a susceptible host
  biological_scale: ORGANISM
  description: >
    Pharyngeal infection with Streptococcus pyogenes is the initiating event. Skin infection is an
    increasingly recognised alternative portal in high-burden tropical settings. Susceptibility is
    conferred largely by HLA class II genotype, which determines which streptococcal and self
    peptides are presented to CD4-positive T cells, so the same exposure produces disease in some
    hosts and not others.
  downstream:
  - target: Molecular mimicry and cross-reactive immune priming
    causal_link_type: DIRECT
    description: >
      Antigens of the organism prime an immune response that does not distinguish them from host
      cardiac and connective tissue proteins.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Acute rheumatic fever (ARF) is an autoimmune disease caused by group A streptococcal infection."
    explanation: States the causal relationship between the streptococcal infection and the autoimmune illness that follows.

- name: Molecular mimicry and cross-reactive immune priming
  biological_scale: MOLECULAR
  description: >
    The group A carbohydrate epitope N-acetylglucosamine and the alpha-helical coiled-coil M protein
    structurally resemble human cardiac myosin and connective tissue proteins closely enough that
    antibodies and T cells raised against the organism bind host tissue. Which host protein is struck
    first is genuinely disputed and is curated as a controversy rather than as settled fact. The
    long-standing answer is cardiac myosin, but myosin is intracellular and therefore hard to reach,
    which motivates an alternative in which extracellular proteins are hit first.
  biological_processes:
  - preferred_term: inflammatory response to antigenic stimulus
    term:
      id: GO:0002437
      label: inflammatory response to antigenic stimulus
    modifier: INCREASED
  downstream:
  - target: Cross-reactive antibody binding and valve endothelial activation
    causal_link_type: DIRECT
    description: >
      Cross-reactive antibody binds the valve surface, whichever host protein it recognises first.
  evidence:
  - reference: PMID:16455580
    reference_title: "Molecular mimicry in the autoimmune pathogenesis of rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Molecular mimicry is a hallmark of the pathogenesis of rheumatic fever where the streptococcal group A carbohydrate epitope, N-acetyl glucosamine, and the a-helical coiled-coil streptococcal M protein structurally mimic cardiac myosin in the human disease, rheumatic carditis"
    explanation: Names both mimicking epitopes and the canonical host target, which is the claim this node rests on.
  - reference: PMID:16455580
    reference_title: "Molecular mimicry in the autoimmune pathogenesis of rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Both B- and T-cell responses are involved in the process, and evidence for the hypotheses of molecular mimicry and epitope spreading are reviewed."
    explanation: Establishes that both arms of adaptive immunity participate, which is why this entry curates a separate antibody node and T cell node rather than one combined immune node.

- name: Cross-reactive antibody binding and valve endothelial activation
  biological_scale: CELLULAR
  description: >
    Cross-reactive antibody binds valve endothelium and upregulates VCAM-1, converting the valve
    surface from a quiescent lining into an adhesive one. This is the step that recruits the cellular
    infiltrate; antibody alone does not destroy the valve.
  cell_types:
  - preferred_term: valve endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  locations:
  - preferred_term: mitral valve
    term:
      id: UBERON:0002135
      label: mitral valve
  downstream:
  - target: CD4-positive T cell infiltration of the valve
    causal_link_type: DIRECT
    description: >
      Adhesion molecule upregulation permits lymphocyte recruitment into a normally avascular tissue.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The purpose of this mini review is to delineate the etiology and pathophysiological mechanisms underlying ARF and RHD."
    explanation: PARTIAL. The review covers this step, but its abstract states scope rather than the VCAM-1 finding itself, so this citation locates the mechanism in the literature without evidencing the specific adhesion molecule claim.

- name: CD4-positive T cell infiltration of the valve
  biological_scale: CELLULAR
  description: >
    CD4-positive T lymphocytes showing degenerate, cross-reactive antigen recognition infiltrate valve
    tissue and myocardium and are considered the prime effectors of valve destruction. Epitope
    spreading broadens the response with each recurrence, which is the mechanistic reason a second
    episode of rheumatic fever damages the valve more than the first, and why prophylaxis against
    reinfection is the whole of secondary prevention.
  cell_types:
  - preferred_term: CD4-positive T cell
    term:
      id: CL:0000624
      label: CD4-positive, alpha-beta T cell
  biological_processes:
  - preferred_term: T cell mediated immunity
    term:
      id: GO:0002456
      label: T cell mediated immunity
    modifier: INCREASED
  downstream:
  - target: Acute valvulitis with Aschoff body formation
    causal_link_type: DIRECT
    description: >
      Sustained lymphocytic and macrophage infiltration organises into the characteristic lesion.
  evidence:
  - reference: PMID:16455580
    reference_title: "Molecular mimicry in the autoimmune pathogenesis of rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recent studies have unraveled the potential pathogenic mechanisms by which the immune response against the group A streptococcus attacks the rheumatic valve leading to chronic rheumatic heart disease."
    explanation: States that the immune response attacks the valve and that this is what produces the chronic disease, which is the causal role this node occupies.

- name: Acute valvulitis with Aschoff body formation
  biological_scale: TISSUE
  description: >
    The histological signature of active carditis, consisting of granulomatous foci of central
    fibrinoid necrosis ringed by lymphocytes, plasma cells, and macrophages, including the Anitschkow
    cells whose linear chromatin gives them their caterpillar appearance. The Aschoff body is a
    pathological structure formed de novo and so is conceptually an Xogenesis lesion, but it is
    deliberately not curated as conforming to the granuloma_formation module. That module models
    containment of an indigestible persistent stimulus by macrophage fusion, and here there is no
    organism in the tissue to contain.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  locations:
  - preferred_term: mitral valve
    term:
      id: UBERON:0002135
      label: mitral valve
  downstream:
  - target: Chronic valve fibrosis, commissural fusion, and calcification
    causal_link_type: DIRECT
    description: >
      Repeated or persistent inflammation converts reversible valvulitis into fixed scar.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recurrent episodes of ARF can lead to rheumatic heart disease (RHD)"
    explanation: PARTIAL. Supports the acute to chronic transition this node sits on, but does not itself describe the Aschoff body, which is drawn from textbook histopathology and is not separately evidenced here.

- name: Chronic valve fibrosis, commissural fusion, and calcification
  biological_scale: TISSUE
  conforms_to: "fibrotic_response#Excessive ECM Deposition"
  description: >
    Leaflet thickening, neovascularisation of a normally avascular tissue, fusion of the commissures,
    and dystrophic calcification convert inflammation into fixed stenosis, regurgitation, or both.
    This is the point of no return, since everything upstream is in principle reversible and nothing
    from here on is. The mitral valve is affected most often and most severely, then the aortic, an
    asymmetry conventionally attributed to the higher shear stress on left-sided valves.
  cell_types:
  - preferred_term: valve interstitial cell
    term:
      id: CL:4030032
      label: valve interstitial cell
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
    modifier: INCREASED
  locations:
  - preferred_term: mitral valve
    term:
      id: UBERON:0002135
      label: mitral valve
  downstream:
  - target: Valvular stenosis and regurgitation with hemodynamic overload
    causal_link_type: DIRECT
    description: >
      Fixed structural valve deformity imposes a pressure or volume load on the chambers upstream.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Recurrent episodes of ARF can lead to rheumatic heart disease (RHD), which is the leading cause of cardiovascular mortality in children worldwide, especially in low- and middle-income countries."
    explanation: States that the recurrent acute episodes produce the chronic disease this node represents, and names its consequence.

- name: Valvular stenosis and regurgitation with hemodynamic overload
  biological_scale: ORGANISM
  description: >
    Mitral regurgitation appears first, mitral stenosis later as leaflets thicken and commissures
    fuse. The resulting left atrial enlargement, pulmonary venous congestion, and ventricular volume
    or pressure overload account for essentially all the downstream clinical disease.
  downstream:
  - target: Atrial fibrillation and cardioembolic risk
    causal_link_type: DIRECT
    description: >
      Left atrial enlargement from mitral disease creates the substrate for atrial fibrillation.
  - target: Congestive heart failure
    causal_link_type: DIRECT
    description: >
      Chronic volume or pressure overload culminates in ventricular failure.
  - target: Pulmonary venous congestion and pulmonary hypertension
    causal_link_type: DIRECT
    description: >
      Mitral stenosis raises left atrial pressure, which is transmitted backwards into the
      pulmonary venous circulation.

- name: Pulmonary venous congestion and pulmonary hypertension
  biological_scale: ORGANISM
  conforms_to: "pulmonary_vascular_remodeling#Obstructive Pulmonary Vascular Remodeling"
  description: >
    Sustained elevation of left atrial pressure in mitral stenosis is transmitted back through the
    pulmonary veins, and chronic passive congestion eventually produces reactive remodelling of the
    pulmonary arterioles. This is post-capillary pulmonary hypertension arising from a mechanical
    upstream cause, so conformance is declared at the remodelling node only and not at the
    module's endothelial and BMPR2 trigger nodes, which model a primary pulmonary arteriopathy.
    The consequence is right ventricular pressure loading, which is how a left-sided valve lesion
    ends in right heart failure.
  downstream:
  - target: Right heart failure
    causal_link_type: DIRECT
    description: >
      Chronically raised pulmonary vascular resistance loads the right ventricle.

- name: Right heart failure
  biological_scale: ORGANISM
  description: >
    Raised jugular venous pressure, hepatic congestion, ascites, and peripheral oedema, arising
    from right ventricular pressure loading rather than from any right-sided valve lesion. Curated
    separately from left-sided congestive failure because the mechanism and the clinical picture
    differ.

- name: Atrial fibrillation and cardioembolic risk
  biological_scale: ORGANISM
  description: >
    Atrial fibrillation here is structural, arising from left atrial enlargement, and is deliberately
    not curated as conforming to cardiac_ion_channel_repolarization. That module models a primary
    channelopathy in a structurally normal heart, which is the opposite of the situation here. The
    distinction is not academic, because it is why this population needs a vitamin K antagonist rather
    than a direct oral anticoagulant, a question settled by trial and against expectation.
  downstream:
  - target: Congestive heart failure
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >
      Loss of atrial contribution and rate irregularity worsen an already loaded ventricle.
  evidence:
  - reference: PMID:36036525
    reference_title: "Rivaroxaban in Rheumatic Heart Disease-Associated Atrial Fibrillation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among patients with rheumatic heart disease-associated atrial fibrillation, vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy, without a higher rate of bleeding."
    explanation: The INVICTUS result, which establishes that this form of atrial fibrillation behaves differently from nonvalvular atrial fibrillation and is the strongest evidence that it should be modelled as a distinct structural entity.

- name: Congestive heart failure
  biological_scale: ORGANISM
  description: >
    The usual presenting syndrome, because chronic rheumatic heart disease is frequently silent until
    it decompensates. That latency is what motivates echocardiographic screening programmes in endemic
    populations.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which is the leading cause of cardiovascular mortality in children worldwide"
    explanation: PARTIAL. Establishes that the disease is lethal but does not name heart failure as the mechanism of death.

phenotypes:
- category: Clinical
  name: Mitral regurgitation
  description: >
    The earliest and most common valvular lesion, present before stenosis develops.
  phenotype_term:
    preferred_term: Mitral regurgitation
    term:
      id: HP:0001653
      label: Mitral regurgitation
  evidence:
  - reference: PMID:22371105
    reference_title: "World Heart Federation criteria for echocardiographic diagnosis of rheumatic heart disease--an evidence-based guideline."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Systematic differences in the reporting of and diagnostic approach to RHD exist, reflecting differences in local experience and disease patterns."
    explanation: PARTIAL. Establishes that the diagnostic approach to these valvular lesions needed standardising, which is context for the lesion rather than evidence of its frequency; the cached abstract does not rank the valve lesions.

- category: Clinical
  name: Mitral stenosis
  description: >
    Develops later than regurgitation, from progressive leaflet thickening and commissural fusion. It
    is the lesion that produces left atrial enlargement, and therefore the atrial fibrillation and
    stroke risk.
  phenotype_term:
    preferred_term: Mitral stenosis
    term:
      id: HP:0001718
      label: Mitral stenosis

- category: Clinical
  name: Aortic regurgitation
  description: >
    The second most commonly involved valve, usually alongside mitral disease and rarely in isolation.
  phenotype_term:
    preferred_term: Aortic regurgitation
    term:
      id: HP:0001659
      label: Aortic regurgitation

- category: Clinical
  name: Atrial fibrillation
  description: >
    Arises from left atrial enlargement in mitral disease and is the main driver of thromboembolic
    stroke risk.
  phenotype_term:
    preferred_term: Atrial fibrillation
    term:
      id: HP:0005110
      label: Atrial fibrillation
  evidence:
  - reference: PMID:36036525
    reference_title: "Rivaroxaban in Rheumatic Heart Disease-Associated Atrial Fibrillation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of 4565 enrolled patients, 4531 were included in the final analysis. The mean age of the patients was 50.5 years, and 72.3% were women."
    explanation: A trial of 4531 patients defined by rheumatic heart disease with atrial fibrillation establishes the association at scale, and incidentally documents the striking female predominance of this disease.

- category: Clinical
  name: Congestive heart failure
  description: >
    Frequently the presenting feature, since the chronic disease is usually asymptomatic until
    decompensation.
  phenotype_term:
    preferred_term: Congestive heart failure
    term:
      id: HP:0001635
      label: Congestive heart failure

- category: Clinical
  name: Stroke
  description: >
    Cardioembolic, arising from atrial fibrillation or valve-associated thrombus. It is the
    complication that makes anticoagulation choice consequential in this population.
  phenotype_term:
    preferred_term: Stroke
    term:
      id: HP:0001297
      label: Stroke
  evidence:
  - reference: PMID:36036525
    reference_title: "Rivaroxaban in Rheumatic Heart Disease-Associated Atrial Fibrillation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy"
    explanation: PARTIAL. Stroke is a component of the composite endpoint rather than separately reported in this abstract, so this supports the embolic risk without quantifying stroke alone.

- category: Clinical
  name: Post-capillary pulmonary hypertension
  description: >
    Pulmonary hypertension arising from chronic left atrial pressure elevation in mitral stenosis,
    and the route by which a left-sided valve lesion produces right heart failure. It is bound to
    the post-capillary term rather than to pulmonary arterial hypertension deliberately: the latter
    is the pre-capillary Group 1 entity, which is precisely what this is not, and binding it would
    make the machine-readable slot contradict the prose.
  phenotype_term:
    preferred_term: Post-capillary pulmonary hypertension
    term:
      id: HP:0033635
      label: Post-capillary pulmonary hypertension

- category: Clinical
  name: Migratory polyarthritis
  description: >
    An acute rheumatic fever manifestation rather than a feature of the chronic valvular disease.
    Classically large-joint, fleeting, asymmetric, and strikingly aspirin-responsive.
  phenotype_term:
    preferred_term: Arthritis
    term:
      id: HP:0001369
      label: Arthritis
    temporality: ACUTE

- category: Neurologic
  name: Sydenham chorea
  description: >
    A delayed neurological manifestation appearing one to eight months after the streptococcal
    infection, long after the other features have resolved, which is why it is accepted on its own as
    presumptive evidence of acute rheumatic fever. Most affected individuals have concurrent cardiac
    involvement.
  phenotype_term:
    preferred_term: Chorea
    term:
      id: HP:0002072
      label: Chorea

- category: Clinical
  name: Subcutaneous nodules
  description: >
    Firm painless nodules over extensor surfaces. Uncommon, but they almost always accompany carditis,
    which makes them a useful clinical marker of cardiac involvement.
  phenotype_term:
    preferred_term: Subcutaneous nodule
    term:
      id: HP:0001482
      label: Subcutaneous nodule

- category: Clinical
  name: Fever
  description: >
    A minor Jones criterion during the acute episode.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
    temporality: ACUTE

genetic:
- name: HLA-DQB1
  gene_term:
    preferred_term: HLA-DQB1
    term:
      id: hgnc:4944
      label: HLA-DQB1
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >
    The class II signal in the South Asian genome-wide association study, and a susceptibility
    allele rather than a pathogenic variant. It is curated with an explicit caveat: this signal did
    not reach genome-wide significance and was the third strongest in that study, behind the class
    III and class I signals. The mechanism by which class II variation acts is the one this entry
    already models, namely which streptococcal and self peptides are presented to CD4-positive T
    cells.
  evidence:
  - reference: PMID:32488134
    reference_title: "The Human Leukocyte Antigen Locus and Rheumatic Heart Disease Susceptibility in South Asians and Europeans."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The second and third strongest signals were found in the class I (HLA-B, rs3819306, P = 1.91×10−7) and class II (HLA-DQB1, rs28724238, P = 7.77×10−7) regions, respectively."
    explanation: Locates the class II signal at HLA-DQB1 specifically. PARTIAL because at P = 7.77 x 10 to the minus 7 it falls short of genome-wide significance and ranks third in this study, so it supports a contributory role rather than an established one.

- name: HLA-DRB1
  gene_term:
    preferred_term: HLA-DRB1
    term:
      id: hgnc:4948
      label: HLA-DRB1
  relationship_type: SUSCEPTIBILITY
  variant_origin: GERMLINE
  notes: >
    A class II allele showing the most consistent associations across African, South Asian, and Latin
    American cohorts, though the specific risk alleles differ by ancestry.
  evidence:
  - reference: PMID:24581333
    reference_title: "Rheumatic heart disease in Uganda: the association between MHC class II HLA DR alleles and disease: a case control study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This study compares the frequency of HLA class II DR alleles between RHD cases and normal controls in Uganda."
    explanation: States the design that produced the HLA-DR association, in a sub-Saharan African population where the disease burden is high.

inheritance:
- name: Polygenic susceptibility
  description: >
    Not Mendelian. Susceptibility is polygenic, dominated by HLA class II and class III variation with
    contributions from the immunoglobulin heavy chain locus, and it acts only in combination with the
    environmental exposure. No genetic test is used in management.
  inheritance_term:
    preferred_term: Polygenic inheritance
    term:
      id: HP:0010982
      label: Polygenic inheritance
  evidence:
  - reference: PMID:32488134
    reference_title: "The Human Leukocyte Antigen Locus and Rheumatic Heart Disease Susceptibility in South Asians and Europeans."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These findings suggest the class III region is a key determinant of RHD susceptibility offering important new insight into pathogenesis while partly explaining the inconsistency of earlier reports."
    explanation: Establishes the disease as a susceptibility trait mapped by population association rather than by Mendelian segregation, and notes that earlier reports were inconsistent, which is why this entry curates the inheritance as polygenic rather than naming specific risk alleles.

environmental:
- name: Household crowding and poverty
  exposure_term:
    preferred_term: exposure to adverse socioeconomic factors
    term:
      id: ECTO:6000028
      label: exposure to socioeconomic factors
  description: >
    The dominant determinant of who develops this disease. Crowding drives streptococcal transmission,
    and poverty drives both untreated pharyngitis and failure of secondary prophylaxis. The geographic
    and Indigenous-population disparity in burden is explained by these factors rather than by any
    biological gradient, which is why this entry treats them as mechanism rather than as background.
  influences_mechanisms:
  - target: Group A streptococcal infection in a susceptible host
    environmental_effect: PREDISPOSES
    causal_link_type: DIRECT
    description: >
      Crowding raises the rate of streptococcal transmission and therefore of the initiating infection.
    evidence:
    - reference: PMID:15927077
      reference_title: "Antibiotics for the primary prevention of acute rheumatic fever: a meta-analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Rheumatic fever continues to put a significant burden on the health of low socio-economic populations in low and middle-income countries despite the near disappearance of the disease in the developed world over the past century."
      explanation: Documents the socioeconomic concentration of the disease and its disappearance from wealthy countries, which is the strongest available evidence that the determinant is social rather than biological. PARTIAL because it is an observed distribution rather than a measured exposure effect.
  evidence:
  - reference: PMID:15927077
    reference_title: "Antibiotics for the primary prevention of acute rheumatic fever: a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rheumatic fever continues to put a significant burden on the health of low socio-economic populations in low and middle-income countries despite the near disappearance of the disease in the developed world over the past century."
    explanation: >
      Establishes that the disease is concentrated in low socio-economic populations and has all but
      vanished from wealthy countries, which is the association this exposure entry asserts. PARTIAL
      because it reports where the disease occurs rather than measuring an effect of crowding or of
      poverty.
  notes: >
    ECTO:6000028 (exposure to socioeconomic factors) is bound as the closest available term. It
    covers the poverty dimension but not household crowding, for which the exposure hierarchy has no
    term, so this entry's name is deliberately broader than its binding. An earlier version of this
    note said no term was bound; the binding was added afterwards, by the #8430 exposure-binding
    sweep, which did not revisit the note.

experimental_models:
- name: Lewis rat autoimmune valvulitis model
  description: >
    The principal animal model, produced by immunising Lewis rats with streptococcal M protein or
    cardiac myosin. It reproduces the valvulitis and the cross-reactive immune response, which is what
    established molecular mimicry as more than an observation about sequence similarity. It is
    explicitly the subject of a published discussion of what a robust model of this disease would have
    to demonstrate, which is a fair signal that the existing models are not considered settled.
  experimental_model_type: OTHER
  organism:
    preferred_term: Norway rat
    term:
      id: NCBITaxon:10116
      label: Rattus norvegicus
  modeled_mechanisms:
  - target: Molecular mimicry and cross-reactive immune priming
    description: >
      Immunisation with M protein or cardiac myosin reproduces the cross-reactive response.
  - target: Acute valvulitis with Aschoff body formation
    description: >
      The model develops valvulitis, the acute lesion of this disease.
  publication: PMID:25414841
  evidence:
  - reference: PMID:25414841
    reference_title: "Animal models to investigate the pathogenesis of rheumatic heart disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Antibody and T cell responses to recombinant GAS M protein (rM) and the subsequent interactions with cardiac tissue have been predominantly investigated using a rat autoimmune valvulitis model."
    explanation: Names this model as the principal system used to study the antibody and T cell responses that this entry curates as separate mechanism nodes.
  - reference: PMID:34026876
    reference_title: "Requirements for a Robust Animal Model to Investigate the Disease Mechanism of Autoimmune Complications Associated With ARF/RHD."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Disease complications triggered by Group A streptococcal (GAS) infection are confined to human and determining the early events leading to pathology requires a robust animal model that reflects the hallmark features of the disease."
    explanation: PARTIAL, and included precisely because it is a statement of inadequacy. The disease is confined to humans, and a paper arguing that a robust model is still required is itself evidence that the existing ones fall short.

treatments:
- name: Benzathine penicillin G secondary prophylaxis
  description: >
    The cornerstone of management, and the only intervention that alters the natural history. It works
    by preventing reinfection and therefore recurrence, not by treating the heart at all. It is given
    as a deep intramuscular injection every three to four weeks for a minimum of five years, often to
    age 21 or for ten years after the episode. The burden of that regimen, monthly painful injections
    in adolescents who feel well, is the principal reason real-world adherence is poor, and adherence
    rather than efficacy is the limiting factor.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Group A streptococcal infection in a susceptible host
    treatment_effect: INHIBITS
    description: >
      Prophylaxis acts on the initiating infection, upstream of every immunological step in this entry.
      Nothing downstream of the valve scar is reversible, which is why the only effective point of
      attack is the trigger.
    evidence:
    - reference: PMID:15927077
      reference_title: "Antibiotics for the primary prevention of acute rheumatic fever: a meta-analysis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Fixed effects, meta-analysis revealed an overall protective effect for the use of antibiotics against acute rheumatic fever of 70% (RR = 0.32; 95% CI = 0.21-0.48)."
      explanation: Quantifies the protective effect of treating the streptococcal infection on the incidence of rheumatic fever, which is the causal link this treatment edge asserts.
  evidence:
  - reference: PMID:15927077
    reference_title: "Antibiotics for the primary prevention of acute rheumatic fever: a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Antibiotics appear to be effective in reducing the incidence of acute rheumatic fever following an episode of suspected GAS pharyngitis. This effect may be achieved at relatively low cost if a single intramuscular penicillin injection is administered."
    explanation: The authors' conclusion, including the cost point that makes this the intervention of choice in the settings where the disease actually occurs.
  - reference: PMID:15927077
    reference_title: "Antibiotics for the primary prevention of acute rheumatic fever: a meta-analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All of the included trials were conducted during the period of 1950 and 1961 and in 8 of the 10 trials the study population consisted of young adult males living on United States military bases."
    explanation: PARTIAL, and an important qualification. The evidence base for the central preventive intervention is seventy-year-old trials in young American servicemen, a population with almost nothing in common with the children in whom the disease now occurs.

- name: Anti-inflammatory therapy for acute carditis
  description: >
    Aspirin or corticosteroids are given for symptomatic relief of the acute episode. They do not
    protect the valve. This is curated because the negative result matters. The intuitive assumption is
    that suppressing the inflammation which is destroying the valve should preserve it, and the trial
    evidence does not support that. The evidence is old and at substantial risk of bias, so this is a
    failure to demonstrate benefit 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: aspirin
      term:
        id: CHEBI:15365
        label: acetylsalicylic acid
  target_mechanisms:
  - target: Acute valvulitis with Aschoff body formation
    treatment_effect: INHIBITS
    description: >
      The rationale is suppression of the valvular inflammation before it becomes scar.
    evidence:
    - reference: PMID:26017576
      reference_title: "Anti-inflammatory treatment for carditis in acute rheumatic fever."
      supports: REFUTE
      evidence_source: HUMAN_CLINICAL
      snippet: "Little evidence of benefit was found when corticosteroids or intravenous immunoglobulins were used to reduce the risk of heart valve lesions in patients with acute rheumatic fever."
      explanation: Refutes the proposition that suppressing acute inflammation preserves the valve, which is the claim this treatment edge would otherwise assert.
  evidence:
  - reference: PMID:26017576
    reference_title: "Anti-inflammatory treatment for carditis in acute rheumatic fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The antiquity of most of the trials restricted adequate statistical analysis of the data and acceptable assessment of clinical outcomes by current standards. In addition, risk of bias was substantial, so results should be viewed with caution."
    explanation: The reviewers' own caveat, which is why this is curated as absence of demonstrated benefit rather than as established futility.
  - reference: PMID:26017576
    reference_title: "Anti-inflammatory treatment for carditis in acute rheumatic fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Six trials were conducted between 1950 and 1965; one was done in 1990 and the final study was published in 2001."
    explanation: PARTIAL. Dates the evidence base, which is the substance of the caveat above.

- name: Vitamin K antagonist anticoagulation
  description: >
    Warfarin, with a target INR of 2 to 3, for atrial fibrillation or a mechanical valve. This is one
    of the few places in modern cardiology where the older drug won a head-to-head trial. Direct oral
    anticoagulants are standard for nonvalvular atrial fibrillation, and in this population they were
    worse. That result is the practical payoff of modelling rheumatic atrial fibrillation as a
    structural rather than an electrical disease.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: warfarin
      term:
        id: CHEBI:10033
        label: warfarin
  target_mechanisms:
  - target: Atrial fibrillation and cardioembolic risk
    treatment_effect: INHIBITS
    description: >
      Anticoagulation addresses the thromboembolic consequence, not the arrhythmia or the valve.
    evidence:
    - reference: PMID:36036525
      reference_title: "Rivaroxaban in Rheumatic Heart Disease-Associated Atrial Fibrillation."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "vitamin K antagonist therapy led to a lower rate of a composite of cardiovascular events or death than rivaroxaban therapy, without a higher rate of bleeding"
      explanation: Establishes vitamin K antagonism as superior in this specific population, with no bleeding penalty.
  evidence:
  - reference: PMID:36036525
    reference_title: "Rivaroxaban in Rheumatic Heart Disease-Associated Atrial Fibrillation."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Permanent discontinuation of trial medication was more common with rivaroxaban than with vitamin K antagonist therapy at all visits."
    explanation: A secondary finding that complicates the simple reading of the result, since differential discontinuation is itself a candidate explanation for the difference in outcome.

- name: Low-molecular-weight heparin anticoagulation in pregnancy
  description: >
    Pregnancy is the period of highest thromboembolic risk in a woman with a prosthetic valve, and
    it is also when warfarin cannot be used, because it crosses the placenta and is teratogenic in
    the first trimester. Low-molecular-weight heparin is the usual substitute and remains an
    off-label indication without an agreed regimen, which is a substantial evidence gap in a
    disease whose population is overwhelmingly young women. The modality is recorded as OTHER
    rather than SMALL_MOLECULE, since a low-molecular-weight heparin is a sulfated polysaccharide
    rather than a small molecule in the usual sense.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_mechanisms:
  - target: Valvular stenosis and regurgitation with hemodynamic overload
    treatment_effect: INHIBITS
    description: >
      The thromboembolic risk this addresses arises from the prosthetic valve implanted to treat
      the valvular lesion, so the edge is drawn to the valve node rather than to atrial
      fibrillation. The cited study is specifically about women with prosthetic valve replacement,
      and attributing it to the arrhythmia would misstate what was measured.
  evidence:
  - reference: PMID:35464573
    reference_title: "The Safety and Efficacy of Low-Molecular-Weight Heparin in Pregnant Women With Rheumatic Heart Disease and Valves Replacement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In patients with rheumatic heart disease (RHD) and prosthetic valve replacement, the risk of thromboembolic complications is the highest during and immediately after pregnancy."
    explanation: Establishes pregnancy as the period of peak thromboembolic risk in this population, which is why the anticoagulation question is acute here.
  - reference: PMID:35464573
    reference_title: "The Safety and Efficacy of Low-Molecular-Weight Heparin in Pregnant Women With Rheumatic Heart Disease and Valves Replacement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The use of low-molecular-weight heparin (LMWH) remains an off-label indication."
    explanation: PARTIAL, and recorded because it is a limitation rather than a result. The standard of care in the highest-risk period of this disease rests on off-label use.
  - reference: PMID:35464573
    reference_title: "The Safety and Efficacy of Low-Molecular-Weight Heparin in Pregnant Women With Rheumatic Heart Disease and Valves Replacement."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LMWH is both safe and effective in preventing major thromboembolic complications compared to other forms of anticoagulation used during pregnancy."
    explanation: The efficacy finding itself, from what its authors describe as the largest retrospective series of anticoagulation options in this specific population. It is retrospective, which is why the off-label caveat above is retained alongside it.

- name: Percutaneous balloon mitral valvuloplasty
  description: >
    Mechanical relief of rheumatic mitral stenosis in suitable valves, meaning those that are not
    calcified and not significantly regurgitant. It is less invasive and cheaper than surgery, which
    matters disproportionately in the settings where this disease actually occurs.
  therapeutic_modality: DEVICE
  treatment_term:
    preferred_term: Therapeutic Procedure
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  target_mechanisms:
  - target: Valvular stenosis and regurgitation with hemodynamic overload
    treatment_effect: BYPASSES
    description: >
      Splitting the fused commissures relieves the obstruction without addressing the scar itself.

- name: Mitral valve repair or replacement
  description: >
    Required for advanced, calcified, or regurgitant disease. Repair outperforms replacement where
    anatomically feasible. Mechanical replacement commits a young patient to lifelong anticoagulation,
    with the accumulating risks of thromboembolism, haemorrhage, perivalvular leak, and prosthetic
    endocarditis, which is a heavy long-term cost in the adolescents and young adults who make up much
    of this population.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: Surgical Procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  target_mechanisms:
  - target: Valvular stenosis and regurgitation with hemodynamic overload
    treatment_effect: BYPASSES
    description: >
      Replacing or repairing the valve restores competent flow without reversing the disease process.

diagnosis:
- name: Echocardiography using World Heart Federation criteria
  description: >
    The central diagnostic modality for chronic disease, and the basis of screening for latent disease
    in endemic populations. The criteria classify findings as definite, borderline, or normal, and were
    written specifically to standardise detection of subclinical disease so that people can be enrolled
    in prophylaxis before they become symptomatic.
  evidence:
  - reference: PMID:22371105
    reference_title: "World Heart Federation criteria for echocardiographic diagnosis of rheumatic heart disease--an evidence-based guideline."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Over the past 5 years, the advent of echocardiographic screening for rheumatic heart disease (RHD) has revealed a higher RHD burden than previously thought."
    explanation: States what echocardiographic screening actually established, namely that the burden is larger than clinical detection had suggested, which is the reason these criteria exist.

- name: Evidence of antecedent streptococcal infection
  description: >
    Throat culture or rapid antigen testing for the acute infection, and anti-streptolysin O and
    anti-DNase B titres for antecedent infection. This is a mandatory element of the Jones
    criteria, not a supporting investigation, because the entire causal claim of the disease rests
    on a preceding streptococcal infection that has usually resolved by the time the patient
    presents.

- name: Revised Jones criteria
  description: >
    The clinical diagnostic framework for the acute episode, revised in 2015 to stratify by population
    risk, to incorporate Doppler echocardiography for subclinical carditis, and to accept isolated
    chorea as presumptive disease. The risk stratification is unusual and worth noting, because the
    same findings mean different things depending on the local incidence, which is an explicit
    acknowledgement that pretest probability differs enormously between populations.
  evidence:
  - reference: PMID:25908771
    reference_title: "Revision of the Jones Criteria for the diagnosis of acute rheumatic fever in the era of Doppler echocardiography: a scientific statement from the American Heart Association."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The goal of this statement was to review the historic Jones criteria used to diagnose acute rheumatic fever in the context of the current epidemiology of the disease and to update those criteria to also take into account recent evidence supporting the use of Doppler echocardiography in the diagnosis of carditis as a major manifestation of acute rheumatic fever."
    explanation: States the purpose of the revision and, specifically, the elevation of Doppler-detected carditis to a major manifestation, which is the substantive change this diagnostic entry describes.

progression:
- phase: Acute rheumatic fever
  notes: >
    The acute multisystem episode, typically at age five to fourteen, with carditis, migratory
    arthritis, chorea, and skin manifestations in varying combination. Valvulitis at this stage is
    in principle reversible.
- phase: Latent chronic valve disease
  notes: >
    Often clinically silent for years while fibrosis progresses, which is the reason
    echocardiographic screening exists in endemic populations and the reason the disease is
    frequently first diagnosed at the point of decompensation.
- phase: Progression by severity at diagnosis
  notes: >
    Severity at diagnosis is the dominant prognostic determinant, and the trajectories diverge
    sharply. Severe disease is close to a surgical diagnosis; mild disease is mostly stable but
    not benign, since a tenth still progress to severe.
  evidence:
  - reference: PMID:28255075
    reference_title: "Rheumatic Heart Disease Severity, Progression and Outcomes: A Multi-State Model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Of 96 (16.2%) patients with severe RHD at diagnosis, 50% had proceeded to valve surgery by 2 years, and 10% were dead within 6 years."
    explanation: Quantifies the trajectory of severe disease at diagnosis with counted denominators from a register-based cohort of 591 patients.
  - reference: PMID:28255075
    reference_title: "Rheumatic Heart Disease Severity, Progression and Outcomes: A Multi-State Model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with mild RHD at diagnosis were the most stable, with 64% remaining mild after 10 years; however, 11.4% progressed to severe RHD and half of these required surgery."
    explanation: Quantifies the mild-disease trajectory, including the minority who progress, which is what makes surveillance of mild disease worthwhile rather than reassuring.
- phase: Decompensation and surgery
  notes: >
    Heart failure, atrial fibrillation with embolic risk, and the need for valve intervention. In
    the cohort above the prognosis of young Indigenous Australians with severe disease is described
    by its authors as bleak, with the explicit conclusion that only earlier detection and treatment
    will change it.
  evidence:
  - reference: PMID:28255075
    reference_title: "Rheumatic Heart Disease Severity, Progression and Outcomes: A Multi-State Model."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The prognosis of young Indigenous Australians diagnosed with severe RHD is bleak; interventions must focus on earlier detection and treatment if the observed natural history is to be improved."
    explanation: The authors' own conclusion, which is also the argument for the screening programmes curated in the diagnosis section.

prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: ABOVE_1_IN_1000
  notes: >
    Concentrated in low- and middle-income countries and in Indigenous populations of wealthy ones.
    The class here is deliberately coarse, because no cited source in this entry states a rate.
  evidence:
  - reference: PMID:40276383
    reference_title: "A mini review of the pathogenesis of acute rheumatic fever and rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which is the leading cause of cardiovascular mortality in children worldwide, especially in low- and middle-income countries"
    explanation: PARTIAL. Establishes the global burden and its distribution, but states a rank rather than a rate, so the prevalence class is coarse and no numeric figure is asserted.

biochemical:
- name: Anti-streptolysin O titre
  presence: INCREASED
  notes: >
    Serological evidence of antecedent group A streptococcal infection, which is a mandatory
    requirement of the Jones criteria rather than an optional supporting test. Sensitivity is
    roughly eighty percent, so it is paired with anti-DNase B; the two together detect
    substantially more antecedent infections than either alone. A rising or falling paired titre is
    more informative than a single value, because the organism has usually gone by the time the
    illness appears.

- name: Anti-DNase B titre
  presence: INCREASED
  notes: >
    The complementary streptococcal antibody, with sensitivity around ninety percent, and
    particularly useful when the antecedent infection was cutaneous rather than pharyngeal.

- name: C-reactive protein
  presence: INCREASED
  notes: >
    An acute-phase reactant and a minor Jones criterion. It is non-specific, and its role is to
    corroborate active inflammation during the acute episode rather than to diagnose the disease.

- name: Erythrocyte sedimentation rate
  presence: INCREASED
  notes: >
    The other acute-phase minor criterion, used alongside C-reactive protein to document ongoing
    inflammation and to follow its resolution.

differential_diagnoses:
- name: Infective endocarditis
  description: >
    The critical distinction, and it runs in both directions. Infective endocarditis is an infection of
    the valve requiring prolonged antimicrobial therapy, whereas rheumatic heart disease is an
    autoimmune sequela in which the organism is absent from the valve. The two are also linked, because
    a rheumatic valve is a substrate on which infective endocarditis subsequently develops.
- name: Juvenile idiopathic arthritis
  description: >
    Shares the migratory arthritis of the acute episode. The distinguishing features are streptococcal
    serology, the exquisite aspirin responsiveness, and the presence of carditis.
- name: Nonvalvular atrial fibrillation
  description: >
    Not a differential for the disease itself but for its management. Treating rheumatic atrial
    fibrillation as though it were nonvalvular leads to the choice of a direct oral anticoagulant,
    which the INVICTUS trial showed to be inferior here.

discussions:
- discussion_id: initial_autoantigen_disputed
  kind: CONTROVERSY
  status: OPEN
  prompt: >
    Is cardiac myosin the initial target of the cross-reactive immune response, or is it reached only
    after extracellular proteins have been damaged first?
  rationale: >
    The textbook account, well supported by sequence mimicry and by animal models immunised with M
    protein and cardiac myosin, is that cardiac myosin is the cross-reactive target. The objection is
    mechanical rather than immunological. Myosin is intracellular and therefore not accessible to
    circulating antibody in an intact cell, so it is an odd candidate for the first thing an antibody
    binds. The alternative proposes that extracellular and cell-surface proteins are hit first, namely
    laminin, collagen IV, the coxsackievirus-adenovirus receptor, and the beta-1 adrenergic receptor,
    with the response drifting to myosin and actin only after cells are damaged and their contents
    exposed. This is not merely a question of ordering. If the initial targets are extracellular, then
    those are the antigens a vaccine or a tolerising therapy would have to account for, and the animal
    models that immunise directly with myosin may be reproducing a late stage of the disease while
    skipping the step that actually initiates it.
  attaches_to:
  - pathophysiology#Molecular mimicry and cross-reactive immune priming
  evidence:
  - reference: PMID:25191648
    reference_title: "Rethinking Molecular Mimicry in Rheumatic Heart Disease and Autoimmune Myocarditis: Laminin, Collagen IV, CAR, and B1AR as Initial Targets of Disease."
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: "But myosin and actin are immunologically inaccessible and unlikely initial targets. Extracellular cardiac proteins that mimic GAS and CX would be more likely."
    explanation: States the objection to the canonical model in its own terms, along with the reasoning behind the alternative.
  - reference: PMID:25191648
    reference_title: "Rethinking Molecular Mimicry in Rheumatic Heart Disease and Autoimmune Myocarditis: Laminin, Collagen IV, CAR, and B1AR as Initial Targets of Disease."
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: "Epitope drift shifts the immune response to myosin and actin after cardiomyocytes become damaged."
    explanation: The proposed reconciliation, in which both models describe different stages. PARTIAL because it arises from sequence-similarity searching rather than from a demonstrated sequence of events in patients.
  - reference: PMID:16455580
    reference_title: "Molecular mimicry in the autoimmune pathogenesis of rheumatic heart disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the a-helical coiled-coil streptococcal M protein structurally mimic cardiac myosin in the human disease, rheumatic carditis, and in animal models immunized with streptococcal M protein and cardiac myosin"
    explanation: The canonical position, which this discussion weighs against the alternative rather than discards.
  proposed_experiments:
  - experiment_id: exp_serial_autoantibody_profiling
    name: Serial autoantibody specificity profiling from streptococcal pharyngitis through acute rheumatic fever
    description: >-
      Serially profile antibody specificity against laminin, collagen IV, the coxsackievirus-adenovirus
      receptor, the beta-1 adrenergic receptor, and cardiac myosin in a prospective cohort followed from
      streptococcal pharyngitis through any subsequent acute rheumatic fever. If extracellular targets
      are struck first, antibodies against them should precede anti-myosin antibodies rather than
      appear alongside them.

- discussion_id: anti_inflammatory_treatment_does_not_protect_the_valve
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >
    Given that immune-mediated valvulitis is what destroys the valve, why does anti-inflammatory
    treatment during the acute episode fail to reduce valve damage, and is that negative result real?
  rationale: >
    Every step in this entry's causal chain predicts that suppressing acute inflammation should
    preserve the valve, and the trial evidence does not show it. There are at least three readings and
    they carry different consequences. The damage may already be done by the time carditis is
    clinically apparent, in which case the intervention is simply too late and earlier detection is the
    answer. The agents tested may be too weak or wrongly targeted, in which case a modern trial with
    better drugs is warranted. Or the trials themselves, six of eight conducted between 1950 and 1965
    with substantial risk of bias, may simply be incapable of detecting an effect that exists. The
    reviewers call for new trials, which is a statement that they regard the question as open rather
    than answered. This matters because in the absence of a valve-protective therapy the entire burden
    of preventing this disease falls on prophylaxis and adherence.
  attaches_to:
  - pathophysiology#Acute valvulitis with Aschoff body formation
  - pathophysiology#Chronic valve fibrosis, commissural fusion, and calcification
  evidence:
  - reference: PMID:26017576
    reference_title: "Anti-inflammatory treatment for carditis in acute rheumatic fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Little evidence of benefit was found when corticosteroids or intravenous immunoglobulins were used to reduce the risk of heart valve lesions in patients with acute rheumatic fever."
    explanation: The negative finding that this discussion exists to explain.
  - reference: PMID:26017576
    reference_title: "Anti-inflammatory treatment for carditis in acute rheumatic fever."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In addition, risk of bias was substantial, so results should be viewed with caution."
    explanation: PARTIAL. The reviewers' own warning about their result, which is what makes this an open question rather than a settled negative.
  proposed_experiments:
  - experiment_id: exp_modern_anti_inflammatory_trial
    name: Randomised trial of a modern immunomodulator in echocardiographically confirmed acute carditis with valve morphology as the endpoint
    description: >-
      Randomise patients with echocardiographically confirmed acute carditis to a modern
      anti-inflammatory or immunomodulatory agent or placebo, with valve morphology at two years as the
      primary endpoint rather than a clinical composite. The decision criterion is whether valve outcome
      differs. A symptomatic benefit without a structural one would confirm the existing picture rather
      than change it.

- discussion_id: gas_vaccine_as_the_only_route_to_elimination
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >
    Can a group A streptococcal vaccine be developed that prevents this disease without provoking
    the very cross-reactivity that causes it?
  rationale: >
    Every intervention curated in this entry is downstream of an infection that has already
    happened, and the one that works depends on an injection regimen people cannot complete. A
    vaccine is the only intervention that would remove the trigger at population scale, and the
    World Health Organization has published a formal development roadmap and preferred product
    characteristics for one. The difficulty is specific to this disease and follows directly from
    its mechanism. The immunodominant streptococcal antigens are precisely the ones that
    cross-react with cardiac tissue, so a vaccine that raises antibodies against M protein risks
    inducing the autoimmunity it is meant to prevent. Current approaches try to route around this,
    for instance by targeting the L-rhamnose backbone of the group A carbohydrate, chosen because
    the rhamnose biosynthesis pathway is absent from mammalian cells and so cannot be mimicked.
    Whether that avoids cross-reactivity in humans rather than in test animals is unresolved.
  attaches_to:
  - pathophysiology#Group A streptococcal infection in a susceptible host
  - pathophysiology#Molecular mimicry and cross-reactive immune priming
  evidence:
  - reference: PMID:30624673
    reference_title: "The Path to Group A Streptococcus Vaccines: World Health Organization Research and Development Technology Roadmap and Preferred Product Characteristics."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Impediments related to antigen diversity, safety concerns, and the difficulty to establish vaccine efficacy against rheumatic heart disease are discussed."
    explanation: Names the three obstacles to a vaccine, including the specific difficulty of demonstrating efficacy against this disease, which is the substance of this discussion rather than the existence of a roadmap.
  - reference: PMID:30624673
    reference_title: "The Path to Group A Streptococcus Vaccines: World Health Organization Research and Development Technology Roadmap and Preferred Product Characteristics."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Demonstration of vaccine efficacy against pharyngitis and skin infections constitutes a key near-term strategic goal."
    explanation: States the near-term strategy, which is itself informative. Efficacy is to be shown against the infections rather than against this disease, because the rheumatic endpoint is too rare and too delayed to power a trial on directly.
  - reference: PMID:39959434
    reference_title: "Unveiling the Group A Streptococcus Vaccine-Based L-Rhamnose from Backbone of Group A Carbohydrate: Current Insight Against Acute Rheumatic Fever to Reduce the Global Burden of Rheumatic Heart Disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The L-Rhamnose-based vaccine was chosen due to the absence of the Rhamnose biosynthesis pathway in mammalian cells including humans thus this molecule is not found in any body tissue."
    explanation: States the design rationale for avoiding cross-reactivity, namely selecting an antigen with no mammalian counterpart to mimic.
  - reference: PMID:39959434
    reference_title: "Unveiling the Group A Streptococcus Vaccine-Based L-Rhamnose from Backbone of Group A Carbohydrate: Current Insight Against Acute Rheumatic Fever to Reduce the Global Burden of Rheumatic Heart Disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Recent pre-clinical studies reveal that L-Rhamnose-based vaccines provide a protective effect by increasing IgG antibody titers without causing cross-reactive antibodies in test animal tissue."
    explanation: PARTIAL, and deliberately so. The absence of cross-reactivity is demonstrated in test animal tissue, which is exactly the claim that must hold in humans and has not yet been shown to.
  proposed_experiments:
  - experiment_id: exp_gas_vaccine_cross_reactivity_human
    name: Human cardiac tissue cross-reactivity screening of candidate group A streptococcal vaccine antisera
    description: >-
      Screen antisera raised by candidate vaccine antigens against a panel of human cardiac and
      valvular proteins, including cardiac myosin, laminin, collagen IV, and the beta-1 adrenergic
      receptor, before any efficacy trial. The decision criterion is whether cross-reactivity is
      detectable against human rather than animal tissue, since the animal result is what current
      candidates rest on and is not the relevant test.

- discussion_id: prophylaxis_burden_is_the_limiting_factor
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >
    Can secondary prophylaxis be delivered in a form that people will actually complete, and would
    doing so close the gap between its efficacy and its real-world effect?
  rationale: >
    This disease is unusual in having a cheap intervention of established efficacy that reliably fails
    in practice for reasons that are not biological. Benzathine penicillin requires a painful deep
    intramuscular injection every three to four weeks for at least five years, typically in adolescents
    who feel well, in settings with limited health infrastructure. Adherence is correspondingly poor,
    and recurrence follows, which is what converts survivable valve disease into fatal valve disease.
    The gap between efficacy and effectiveness here is arguably the single largest determinant of the
    global burden, and it is a pharmacological and delivery problem rather than a mechanistic one. A
    subcutaneous high-dose formulation permitting less frequent dosing is in early trials.
  attaches_to:
  - treatments#Benzathine penicillin G secondary prophylaxis
  proposed_experiments:
  - experiment_id: exp_long_acting_prophylaxis_outcomes
    name: Long-acting subcutaneous benzathine penicillin versus monthly intramuscular dosing with course completion as a co-primary endpoint
    description: >-
      Randomise patients to a long-acting subcutaneous benzathine penicillin formulation or to standard
      monthly intramuscular dosing, with completion of the prophylaxis course and recurrence of acute
      rheumatic fever as co-primary endpoints. The point is to test whether removing the delivery burden
      closes the efficacy-effectiveness gap, so adherence has to be an endpoint and not a covariate.

notes: >
  Deep-research provenance. Curated from a claude_code deep-research report treated as leads only.
  The report was unusually careful and flagged its own ontology and MONDO identifiers as unverified
  rather than asserting them. Every identifier used here was independently checked against OAK or OLS.

  MONDO term selection. MONDO:0006955 is the live term. MONDO:0000472 also matches a search for this
  disease name and is obsolete; it must not be used.

  NEC preflight returned SKIP, because MONDO records no causal gene for this disease and the
  gene-identity check therefore cannot discriminate. The manual fallback was run. The report is
  unambiguously about rheumatic heart disease throughout, and the apparent top gene hit reported by
  the tool, RHD at 95 mentions, is the tool matching the disease acronym against the unrelated Rh
  blood group gene rather than a genuine gene signal.

  Cochrane version. The report cited the Cochrane review on anti-inflammatory treatment without a
  PMID. Three versions exist, from 2003, 2012, and 2015. The 2015 update, PMID:26017576, is cited
  here. The superseded 2003 version, PMID:12804454, was fetched during curation and is deliberately
  not cited.

  Module conformance. One node conforms to fibrotic_response. The report suggested the Aschoff body
  might conform to granuloma_formation; it is deliberately not curated that way, because that module
  models containment of a persistent indigestible stimulus by macrophage fusion and there is no
  organism in the rheumatic valve to contain. The report also advised against conforming the atrial
  fibrillation to cardiac_ion_channel_repolarization, which is correct and is followed here, since
  this arrhythmia is structural and the INVICTUS result is the clinical consequence of that fact.

  Absent bindings. No ECTO term is available for household crowding or poverty as exposures, which is
  documented on the environmental entry. No therapeutic_agent is bound on the benzathine penicillin
  treatment because the NCIT identifier for the benzathine salt was not confirmed during curation;
  the generic Pharmacotherapy action term is used alone rather than binding an unverified CURIE.
📚

References & Deep Research

Deep Research

1
Claude Code ▸
Rheumatic Heart Disease (RHD) — Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 69 citations 2026-08-10T00:53:54.646450

Rheumatic Heart Disease (RHD) — Comprehensive Research Report

Prepared to populate a disease-knowledge-base entry (pathophysiology graph, phenotype/gene/treatment annotations). Ontology term suggestions are given as best-effort identifiers; because AI-suggested ontology IDs are known to be occasionally wrong, curators should verify every ID/label pair against the authoritative ontology (OAK/OLS) before committing — this report flags terms with lower confidence explicitly.

1. Disease Information

Overview. Rheumatic heart disease (RHD) is the chronic, permanent cardiac valvular damage that results from one or more episodes of acute rheumatic fever (ARF), itself a delayed, non-suppurative autoimmune sequela of mucosal (pharyngeal, and increasingly recognized skin) infection with Group A Streptococcus (GAS, Streptococcus pyogenes) in a genetically susceptible host. ARF is a multisystem inflammatory illness (joints, heart, CNS, skin, subcutaneous tissue); RHD is specifically the residual, usually left-sided, valvular fibrosis/scarring that persists after the acute inflammatory episode(s) resolve. A single severe ARF episode, and more often recurrent episodes, converts initially reversible valvulitis into fixed valve damage — chiefly mitral, then aortic, disease (WHO fact sheet; StatPearls).

Key identifiers: - ICD-10-CM: I00–I02 (acute rheumatic fever, incl. I01. "rheumatic fever with heart involvement"); I05–I09 (chronic rheumatic heart diseases — I05 mitral valve diseases, I06 aortic valve diseases, I07 tricuspid valve diseases, I08 multiple valve diseases, I09 other/unspecified rheumatic heart disease, incl. I09.81 rheumatic heart failure, I09.9 unspecified) (icd10data.com). - MONDO / OMIM / Orphanet: RHD and ARF have MONDO terms integrating DOID/OMIM/Orphanet mappings; exact CURIEs should be confirmed via mondo.monarchinitiative.org lookup before curation (not independently verified in this research pass — flag for OAK confirmation rather than assume a specific numeric ID). - MeSH: "Rheumatic Heart Disease" (D012214); "Rheumatic Fever" (D012213). - Synonyms:* chronic rheumatic valvular heart disease; post-streptococcal valvulitis; rheumatic valve disease; (historical) rheumatic mitral stenosis/regurgitation, rheumatic aortic stenosis/regurgitation as organ-specific labels.

Evidence base character: RHD knowledge is drawn from a mix of aggregated disease-level resources (Global Burden of Disease modeling, national/regional registries such as Australia's RHD registers, WHO fact sheets) and individual-patient data (echocardiographic screening cohorts, hospital case series, and increasingly EHR-linked data in Australia/NZ). Genetic association data come from case-control and GWAS cohorts (South Asia, Aboriginal Australia, sub-Saharan Africa, Brazil, Uganda).

2. Etiology

Primary causal chain: GAS pharyngeal (± skin) infection → in a genetically susceptible host, an aberrant, cross-reactive humoral and cellular immune response → ARF (which may include carditis) → in a subset, and especially with recurrent episodes, permanent valvular fibrosis (RHD). This is fundamentally an infection-triggered autoimmune disease, not a direct infective process of the valve (GAS itself is not found in the damaged valve tissue).

Risk factors

Environmental/host risk factors (WHO; Indigenous HPF): - Poverty, household crowding, and reduced access to healthcare — the dominant social determinants, driving both the incidence of untreated GAS pharyngitis and delayed diagnosis/inadequate secondary prophylaxis. - Age 5–14 years for first ARF episode (peak susceptibility window). - Prior episode(s) of ARF (single strongest risk factor for recurrence/progression — each recurrence compounds valve damage). - Crowded living conditions facilitating GAS transmission (households, boarding schools, remote communities). - Possibly skin GAS infection (impetigo/scabies-associated) as an under-recognized trigger, particularly implicated in some high-burden tropical settings.

Genetic risk factors (see §4 for detail): HLA class II alleles (HLA-DR/DQ), a novel HLA class III susceptibility locus, and candidate non-HLA loci including the immunoglobulin heavy-chain locus (IGHV4-61 region) (Nature Reviews Cardiology genetics review; Sci Rep 2020, PMC7265443).

Protective factors: No robust genetic protective variant is well established; the principal modifiable protective interventions are behavioral/health-system (see §13) rather than intrinsic biological protection. Some HLA alleles show consistent negative (protective) association across cohorts in individual studies, but replication across ancestries is inconsistent (Circulation 1999).

Gene–environment interaction: The core G×E interaction is between host HLA class II genotype (governing which streptococcal/self peptide epitopes are presented to CD4+ T cells) and the degree/recurrence of GAS exposure (itself environmentally/socioeconomically determined) — repeated antigenic exposure in a susceptible HLA background is thought to drive epitope spreading and progressively severe autoimmune valvulitis.

3. Phenotypes

RHD/ARF phenotypes span acute (ARF) manifestations and chronic valvular (RHD) manifestations.

Acute rheumatic fever manifestations (Jones criteria major/minor)

Phenotype Frequency Notes Suggested HPO
Carditis (endocarditis/valvulitis, ± myocarditis, ± pericarditis) Most commonly reported major criterion; subclinical carditis detectable by echo even without murmur Mitral valve most frequent/severe, then aortic HP:0001635 (heart failure, if decompensated); HP:0001653 (mitral regurgitation); HP:0001659 (aortic regurgitation)
Migratory polyarthritis Very common major criterion, classically large joints Fleeting, asymmetric, exquisitely aspirin-responsive HP:0001369 (arthritis)
Sydenham chorea 10–30% of ARF cases; sole finding in ~20% (MedLink/StatPearls search summary) Delayed onset 1–8 months post-GAS; 60–80% have concurrent cardiac involvement HP:0002072 (chorea)
Erythema marginatum <6% of cases Serpiginous, migratory, trunk/limb-sparing face HP:0025590 or search HPO "erythema marginatum"
Subcutaneous nodules <10% of cases Firm, painless, over extensor surfaces; almost always co-occurs with carditis HP:0001482 (subcutaneous nodule)
Fever Minor criterion — HP:0001945
Arthralgia Minor criterion (cannot double-count with major arthritis) — HP:0002829
Elevated ESR/CRP Minor criterion Reflects systemic inflammation HP:0011227 / HP:0011227-adjacent
Prolonged PR interval Minor criterion ECG finding HP:0011703

2015 revised Jones criteria stratify by population risk (low-risk vs. moderate/high-risk, the latter ARF incidence >2/100,000 children/year), formally incorporate Doppler echocardiography for subclinical carditis detection, and treat isolated chorea or indolent carditis as presumptive ARF without requiring other criteria (Gewitz et al., Circulation 2015, PMID 25908771; AAP 2024 specificity analysis).

Chronic RHD manifestations

  • Mitral regurgitation (earliest, most common lesion; HP:0001653) and mitral stenosis (later, from progressive leaflet thickening/fusion; HP:0001718).
  • Aortic regurgitation (HP:0001659) and aortic stenosis (HP:0001650), typically less frequent/severe than mitral disease and rarely isolated.
  • Tricuspid regurgitation, usually functional/secondary to pulmonary hypertension from left heart disease.
  • Atrial fibrillation (HP:0005110), often from left atrial enlargement in mitral stenosis — a major driver of thromboembolic stroke risk.
  • Congestive heart failure (HP:0001635) — dyspnea, edema, orthopnea; often the presenting symptom since chronic RHD is frequently asymptomatic until decompensation.
  • Pulmonary hypertension (HP:0002092), secondary to chronic left-sided valvular disease.
  • Infective endocarditis risk elevated on damaged valves.
  • Stroke/systemic embolism from atrial fibrillation or valve-associated thrombus.

Age of onset: ARF classically presents in school-age children (5–14 yrs); first presentation of RHD (often with a murmur or heart-failure symptoms) may not occur until years later, sometimes not until young adulthood, because chronic RHD is frequently asymptomatic ("latent") until echocardiographic screening or heart failure onset (news-medical.net pathophysiology summary).

Severity/progression pattern (from a prospective severity-progression cohort, JAHA 2017, Multi-State Model, PMID 28255075): - Severe RHD at diagnosis: rapid progression, 50% require surgery within 2 years, 10% die within 6 years. - Moderate RHD: mixed — roughly one-third each progress to severe, remain moderate, or regress to mild over 10 years. - Mild RHD: most favorable — >60% remain mild at 10 years; ~10% become "inactive."

Quality of life: Chronic heart failure, activity limitation, recurrent hospitalization, anticoagulation burden (bleeding risk, INR monitoring), pregnancy risk, and the psychosocial burden of lifelong monthly intramuscular penicillin injections (frequently reported as painful, with poor long-term adherence) all substantially affect QoL, particularly in adolescents and young adults in endemic, resource-limited settings.

4. Genetic/Molecular Information

RHD/ARF is not a monogenic Mendelian disease — it is a complex, polygenic, infection-triggered autoimmune condition with strong immunogenetic (HLA) contribution.

Causal/major-effect loci — HLA class II and III: - HLA-DR and HLA-DQ alleles (class II) show the most consistent associations across African, South Asian, and Latin American cohorts (Nat Rev Cardiol genetics review; Uganda case-control, PMC3943278; Brazil, PMID 2040052). - A GWAS in South Asians (India/Fiji; 672 cases, 491 controls) replicated in a UK Biobank European follow-up (150 cases, 1,309 controls) identified a novel susceptibility signal in the HLA class III region (rs201026476; combined OR 1.81, 95% CI 1.51–2.18, P = 3.48×10⁻¹⁰) (Sci Rep 2020, PMC7265443). - Earlier GWAS work implicated the HLA-DQA1–HLA-DQB1 region and, notably, the immunoglobulin heavy-chain locus (chromosome 14, including the IGHV4-61 gene segment) — supporting a B-cell/antibody-response contribution to susceptibility, consistent with the molecular-mimicry model (biorxiv/GWAS Aboriginal Australians).

Suggested HGNC genes for annotation: HLA-DRB1, HLA-DQA1, HLA-DQB1, IGHV4-61 (contributing locus). Curators should bind via HGNC where a stable symbol exists (HLA genes are commonly annotated at the allele/serotype level rather than single HGNC IDs; verify convention).

Functional impact: These are susceptibility/modifier alleles (not classic pathogenic variants) — appropriate relationship_type is SUSCEPTIBILITY, and inheritance is best modeled as polygenic/complex (HP:0010982-style, if adapting the dismech Inheritance slot) rather than monogenic Mendelian, given no single-gene causal variant explains most cases.

Epigenetics: No well-established disease-specific epigenetic signature has been robustly replicated; this remains an evidence gap.

Chromosomal abnormalities: None reported — RHD is not associated with aneuploidy or structural chromosomal rearrangement; it is a complex autoimmune trait.

Molecular target of the autoimmune response (the "antigen" side): cardiac myosin (α-myosin heavy chain), valve endothelial/interstitial proteins including laminin, collagen IV, cardiac myosin, tropomyosin, keratin, and vimentin, plus the CAR (coxsackievirus-adenovirus receptor) and β1-adrenergic receptor (β1AR) as proposed valve-endothelial/cardiomyocyte targets of cross-reactive antibody (PMC4137453, "Rethinking Molecular Mimicry"). Suggested UniProt/HGNC anchors: MYH6 (cardiac myosin heavy chain, alpha), VIM (vimentin), LAMA2/laminin family, COL4A1 and related collagen IV genes, ADRB1 (β1-adrenergic receptor).

5. Environmental Information

  • Infectious trigger: Streptococcus pyogenes (Group A Streptococcus), primarily via pharyngeal infection; skin infection (impetigo) is an increasingly recognized alternative/contributing portal in some high-incidence tropical settings. NCBITaxon: NCBITaxon:1314 (Streptococcus pyogenes).
  • Socioeconomic/environmental risk factors: overcrowded housing, poverty, limited access to primary healthcare and diagnostic microbiology, and reduced access to secondary prophylaxis programs are the dominant modifiable environmental determinants — these explain most of the geographic and Indigenous-population disparity in disease burden (see §9) (Far North Queensland temporospatial study, PLOS NTD).
  • Lifestyle factors: No specific diet/exercise/substance-use risk modifiers are established beyond the crowding/transmission pathway above; adherence behavior to secondary prophylaxis is itself a major modifiable "environmental" determinant of RHD progression.
  • ECTO/exposure-term candidates: exposure to overcrowded housing; exposure to Streptococcus pyogenes (a term for GAS mucosal/skin exposure).

6. Mechanism / Pathophysiology

Causal chain (upstream → downstream):

  1. GAS mucosal (pharyngeal ± skin) infection in a genetically susceptible (HLA class II/III) host.
  2. Molecular mimicry / cross-reactive immune priming: The GAS group A carbohydrate epitope (N-acetyl-glucosamine on a rhamnose backbone) and the α-helical coiled-coil M protein structurally mimic host cardiac and connective-tissue antigens — cardiac myosin, laminin, collagen IV, vimentin, tropomyosin, keratin — plus CAR and β1AR on valve endothelium/cardiomyocytes (PMC4137453; PMID 16455580).
  3. B-cell response: cross-reactive antibody (initially IgM, later IgG) is produced against GAS carbohydrate/M-protein epitopes and binds valve endothelium, up-regulating VCAM-1 and promoting inflammatory cell recruitment (Frontiers 2025 pathogenesis review, PMC12018407).
  4. CD4+ T-cell response: CD4+ T lymphocytes, exhibiting a "degenerate" (cross-reactive/promiscuous) pattern of antigen recognition, infiltrate valve tissue and myocardium and are considered the prime effector cells of chronic valvular damage; Th1-skewed, IFN-γ-driven inflammation predominates.
  5. Acute valvulitis/carditis: endothelial activation and immune-cell infiltration produce Aschoff bodies — granulomatous foci of central fibrinoid necrosis surrounded by lymphocytes, plasma cells, macrophages, and pathognomonic Anitschkow cells (activated macrophages with a distinctive "caterpillar"-like linear chromatin pattern) (Wikipedia/Grokipedia histopathology summary; pathology reference PEIR).
  6. Chronic remodeling: repeated/persistent inflammation drives valve leaflet fibrosis, neovascularization (abnormal thick-walled vessels within normally avascular valve tissue), leaflet thickening, commissural fusion, and dystrophic calcification — converting reversible acute valvulitis into fixed stenosis and/or regurgitation, predominantly mitral > aortic > tricuspid.
  7. Hemodynamic/organ-level consequences: valve dysfunction → left atrial enlargement → atrial fibrillation and thrombus formation → stroke/systemic embolism; and/or → pulmonary venous congestion → pulmonary hypertension → right heart failure; and/or → ventricular volume/pressure overload → congestive heart failure.

Cell types involved (candidate CL terms — verify via OAK): CD4+ T lymphocyte (CL:0000624), Th1 cell (CL:0000545), B lymphocyte / plasma cell (CL:0000236 / CL:0000786), macrophage (CL:0000235), activated/"Anitschkow" macrophage (no dedicated CL term — annotate as macrophage with a descriptive qualifier), valve endothelial cell (CL:0000115 generic endothelial cell, or a valve-specific subtype if available), valve interstitial fibroblast (CL:0000057 fibroblast).

Biological processes (candidate GO terms): antigen processing and presentation (GO:0019882), T-cell mediated cytotoxicity (GO:0001913), complement activation (GO:0006956), acute inflammatory response (GO:0002526), positive regulation of leukocyte cell-cell adhesion / VCAM-1-mediated adhesion (GO:1903039-family), fibrosis-related extracellular matrix remodeling processes (as used elsewhere in the KB's fibrotic_response module).

Relationship to existing dismech mechanism modules: RHD is a strong candidate to conforms_to the fibrotic_response module (chronic valvulitis → mesenchymal/valve interstitial cell activation → excessive ECM deposition → organ [valve] dysfunction), the cardiomyopathy_maladaptive_remodeling module if ventricular remodeling/heart failure nodes are curated, and cardiac_ion_channel_repolarization is not the right fit for the AF here (RHD-associated AF is structural/left-atrial-enlargement-driven, not a primary channelopathy) — model AF as a downstream structural consequence rather than conforming to that module. The granulomatous Aschoff-body lesion itself may be a candidate for an "Xogenesis"-style pathological-structure-formation node (a defined pathological granulomatous body, analogous to the granuloma_formation module's macrophage-fusion pattern, though Aschoff bodies are histologically and immunologically distinct from infectious/mycobacterial granulomas and a new/adapted anchor would be needed rather than direct conformance).

Molecular profiling / omics: RHD mechanistic omics data are comparatively sparse relative to other cardiovascular diseases; most mechanistic evidence derives from immunohistochemistry of excised valve/appendage tissue, serologic/antibody studies, and the Lewis-rat model transcriptome/histology (see §15) rather than large-scale human transcriptomic/proteomic atlases. This is a notable evidence gap relative to better-profiled cardiovascular conditions.

7. Anatomical Structures Affected

Organ level: - Primary: heart valves — mitral valve (most common and most severely affected; UBERON candidate: UBERON:0002094 mitral valve or generic UBERON:0002136/verify), aortic valve (UBERON:0002137-family, verify), less commonly tricuspid valve, rarely pulmonary valve. - Secondary/associated in ARF (not RHD per se): joints (synovium, UBERON:0000980 synovial joint) in migratory polyarthritis; basal ganglia/caudate-putamen (UBERON:0002420 basal ganglia region) in Sydenham chorea; skin/subcutaneous tissue in erythema marginatum and subcutaneous nodules; pharynx (UBERON:0000165) as the primary infection site. - Body systems: cardiovascular (primary), musculoskeletal (ARF arthritis), nervous (ARF chorea), integumentary (ARF skin findings), and secondarily respiratory (pulmonary hypertension/congestion from left heart disease).

Tissue/cell level: valve leaflet fibrous layer, valve endothelium, myocardial interstitium (Aschoff bodies classically myocardial/subendocardial), pericardium (pericarditis in severe carditis). Cell populations: valve endothelial cells, valve interstitial fibroblasts, infiltrating CD4+ T cells, macrophages/Anitschkow cells, plasma cells.

Subcellular: no disease-defining subcellular organelle lesion (this is an extracellular-matrix/immune-infiltrate disease rather than an organellopathy); GO Cellular Component annotations would center on extracellular matrix (GO:0031012) and cell surface/plasma membrane VCAM-1 (GO:0009986 cell surface) rather than intracellular compartments.

Localization/laterality: left-sided valves (mitral, then aortic) affected far more often and more severely than right-sided valves — a consistent, mechanistically notable asymmetry attributed to higher hemodynamic shear stress on the left side of the heart amplifying endothelial activation/antibody deposition.

8. Temporal Development

  • Onset: ARF typically presents in school-age children (5–14 years), 1–5 weeks after GAS pharyngitis (except Sydenham chorea, which can be delayed 1–8 months). Chronic RHD may not become clinically apparent (murmur, symptoms) until years to decades later; latent RHD (echocardiographically detectable, subclinical) is a recognized and common intermediate state, especially in endemic screening cohorts.
  • Progression pattern: Variable and stage-dependent (see severity data in §3): mild disease is often stable/regressive; moderate disease shows a roughly even three-way split (progress/stable/regress) over a decade; severe disease at diagnosis progresses rapidly, with a high 2-year surgical intervention rate and appreciable 6-year mortality (JAHA multi-state model, PMID 28255075).
  • Disease course: classically episodic-to-progressive — each ARF recurrence adds incremental, cumulative valvular damage; disease is not typically "relapsing-remitting" in the neurological sense but rather step-wise worsening punctuated by inflammatory flares (ARF recurrences), against a background of gradually progressive valvular fibrosis/calcification even in inflammation-free intervals.
  • Remission: acute inflammatory episodes (arthritis, fever, even carditis) can resolve completely, especially with anti-inflammatory treatment; however, once structural valve fibrosis/scarring has occurred it is not reversible — "regression" documented in mild latent RHD cohorts likely reflects resolution of reversible valvulitis/edema rather than true fibrotic reversal.
  • Critical intervention window: primary prevention (antibiotic treatment of GAS pharyngitis within 9 days of symptom onset) reliably prevents the first ARF episode; secondary prophylaxis initiated promptly after a first ARF episode, and sustained for years, is the critical window for preventing the cumulative valvular damage that defines RHD.

9. Inheritance and Population

Epidemiology (Global Burden of Disease 2021): - ~40.5 million people affected globally; ~306,000–373,000 deaths annually (~2% of all cardiovascular deaths) (WHO; GBD pediatric RHD 2021, PMC12293350). - ~3.85 million new RHD cases in 2021; global age-standardized incidence rate rose modestly from 55.84 to 66.76 per 100,000 (1990→2021), while age-standardized death rate in children fell ~74% and DALY rate fell from 117.22 to 41.56 per 100,000 over the same period — a "declining severity, persistent/rising incidence, widening inequality" pattern (GBD pediatric analysis, PMC12293350). - Historical benchmark: 1990–2015 GBD estimated 319,400 RHD deaths globally in 2015 (NEJM 2017, PMID 28834488). - Highest incidence in children aged 0–14, concentrated in low- and middle-income countries.

Inheritance pattern: Multifactorial/polygenic, infection-dependent — not a Mendelian single-gene disorder. HLA-associated susceptibility with modest individual-allele effect sizes (e.g., OR ~1.8 for the HLA class III GWAS hit), consistent with a complex trait requiring an environmental (GAS exposure) trigger. No described penetrance/expressivity framework analogous to monogenic disease; no genetic anticipation or germline mosaicism relevance; no described founder-effect variant, though population-specific HLA allele frequencies likely contribute to regional prevalence differences.

Population demographics and geographic distribution: - Highest global rates: sub-Saharan Africa, followed by Aboriginal and Torres Strait Islander Australians, Māori and Pacific Islanders, and South Asia. - Australia (Indigenous disparity): First Nations Australians are ≥60 times more likely to experience ARF/RHD than non-Indigenous Australians; the Northern Territory has one of the highest documented RHD prevalence rates worldwide (~3,005 per 100,000 Indigenous residents). Indigenous communities account for 78% of all RHD cases and 92% of all ARF cases in Australia (2022 data). Mortality rate ratio (Indigenous vs. non-Indigenous), 2013–2017: 15.9 (Excess Deaths, PMC10756360; Indigenous HPF). In Far North Queensland, RHD incidence rose from 4.7 to 49.4 per 100,000/year (1997→2017); 2017 prevalence was 12/1000 Indigenous vs. 2/1000 non-Indigenous (PLOS NTD). - Māori/Pacific Islander (NZ): cumulative ARF hospitalization risk by age 13 is approximately 1 in 150. - Sex ratio: GBD 2021 data indicate women represent just over half of global RHD cases; some regional/age-specific variation exists (e.g., possible sex differences in Sydenham chorea susceptibility) but no large, uniform sex skew is established for ARF susceptibility itself. - Consanguinity/carrier frequency: not applicable in the classic Mendelian sense (complex trait); HLA allele-frequency variation across ancestries is the relevant population-genetic parameter rather than a carrier-frequency concept.

10. Diagnostics

Clinical/serologic tests: - Evidence of preceding GAS infection: throat culture/rapid antigen test (acute infection); anti-streptolysin O (ASOT) — sensitivity ~80% (adult cutoff >240 Todd units, child >320); anti-DNase B — sensitivity ~90%, complementary to ASOT (paired/sequential titers recommended for optimal sensitivity) (search summary of Frontiers 2021, "Holy Grail" review). - Inflammatory markers: ESR and CRP — elevated as ARF minor criteria; positively correlate with ASOT; may help monitor transition from acute carditis toward chronic RHD. - Electrocardiography: prolonged PR interval (minor Jones criterion); atrial fibrillation detection in chronic disease. - Echocardiography (the central chronic-disease diagnostic modality): 2D + continuous-wave + color-Doppler echo per the 2012 World Heart Federation (WHF) criteria, which classify findings into "definite RHD" (4 subcategories), "borderline RHD" (3 subcategories), and "normal", with age-based modifications for those >20 years — designed to standardize detection of latent/subclinical disease for enrollment into secondary-prophylaxis programs (Reményi et al., Nat Rev Cardiol 2012, PMID 22371105; WHF PDF). Simplified screening criteria have since been validated to predict progression of latent disease (Circ Cardiovasc Imaging, search summary). - Histopathology (rarely obtained clinically; mainly surgical/autopsy specimens): Aschoff bodies and Anitschkow cells in active carditis; chronic valve leaflet fibrosis, neovascularization, and dystrophic calcification in end-stage disease.

Genetic testing: RHD is not currently subject to clinical genetic testing — there is no validated single-gene, panel, or polygenic-risk-score test used in patient management; genetic association findings (HLA, IGH locus) remain research-stage.

Clinical diagnostic criteria: Revised (2015) Jones criteria, risk-stratified by population ARF incidence, incorporating echocardiography and presumptive-ARF categories for isolated chorea/indolent carditis/recurrence (Gewitz et al. 2015, PMID 25908771). Differential diagnosis of ARF includes reactive arthritis, septic arthritis, juvenile idiopathic arthritis, systemic lupus erythematosus, viral myocarditis/pericarditis, infective endocarditis, and (for chorea) other movement disorders (tic disorders, Huntington disease in adults, drug-induced chorea).

Screening: Active echocardiographic screening programs in endemic/high-risk populations (e.g., Australia, Pacific, sub-Saharan Africa) using WHF criteria to detect latent RHD before clinical presentation, enabling early enrollment in secondary prophylaxis — though the clinical/cost-effectiveness value of screening asymptomatic borderline disease remains an area of active debate (Nat Rev Cardiol WHF criteria paper; Global Heart 2023 review of WHF criteria performance).

11. Outcome/Prognosis

  • Mortality: GBD 2021 attributes ~306,000–373,000 deaths/year to RHD globally; nearly 2% of all cardiovascular deaths. Pediatric age-standardized RHD death rate fell ~74% from 1990–2021, reflecting improved secondary prophylaxis and surgical access in many settings, but absolute burden remains high in under-resourced regions.
  • Survival by severity at diagnosis (JAHA 2017 multi-state model):
  • Severe RHD: 50% require surgery within 2 years; 10% die within 6 years.
  • Moderate RHD: ~1/3 progress to severe, ~1/3 stable, ~1/3 regress to mild over 10 years.
  • Mild RHD: >60% remain mild at 10 years; ~10% become inactive.
  • Disability burden: RHD causes the highest DALYs of any cardiovascular disease among 10–14-year-olds globally — reflecting its unique concentration in children/young people relative to other, older-onset cardiovascular conditions.
  • Complications driving morbidity: progressive heart failure, atrial fibrillation, cardioembolic stroke, infective endocarditis, pulmonary hypertension, and — in higher-resource settings — the risks/burdens of anticoagulation and prosthetic valve surgery (thromboembolism ~11% cumulative incidence over 25 years post-mechanical mitral valve replacement in one cohort; rising rates of intracranial hemorrhage, perivalvular leak, and infective endocarditis over time on mechanical valves — search summary of valve-surgery outcome literature).
  • Prognostic factors: severity of carditis at first presentation is the single strongest prognostic determinant; timely secondary prophylaxis adherence, access to echocardiographic monitoring, and access to timely valve surgery in low-resource settings are the major modifiable prognostic levers.

12. Treatment

Pharmacotherapy — acute rheumatic fever

  • Aspirin (CHEBI:15365) — first-line anti-inflammatory for arthritis/mild carditis; 50–60 mg/kg/day, tapered over 1–2 weeks after symptom resolution.
  • NSAIDs (e.g., naproxen, CHEBI:7476) — endorsed alternative to aspirin with comparable efficacy and fewer GI side effects in comparative pediatric trials.
  • Corticosteroids (e.g., prednisone/prednisolone, CHEBI:8382) — reserved for moderate-to-severe carditis; a Cochrane systematic review found no robust evidence that anti-inflammatory treatment (steroids or aspirin) prevents or reduces long-term cardiac valve damage, despite symptomatic benefit (Cilliers et al., Cochrane 2015) — an important evidence caveat for curation (treat as symptomatic, not disease-modifying for valve outcome).

Antibiotic therapy (both eradication and secondary prophylaxis)

  • Benzathine penicillin G (BPG), CHEBI (verify exact CURIE for the benzathine salt) — the cornerstone of both (a) eradication of the inciting GAS infection and (b) secondary prophylaxis: standard dosing is 1.2 million units (900 mg) deep IM every 3–4 weeks for a minimum of 5 years, often extended to age 21 or 10 years post-ARF episode (regimen duration guidance varies by carditis severity per AHA/WHO guidance) (AAC 2023 phase 1 PK study, PMC10720493).
  • Adherence challenge: dosing frequency and injection pain drive suboptimal real-world adherence; a subcutaneous high-dose BPG infusion formulation is under phase 1 investigation to allow less-frequent dosing (PMC10720493).
  • Primary prevention: oral penicillin V or single-dose IM BPG for confirmed/probable GAS pharyngitis, started within 9 days of symptom onset, reduces ARF attack rate by ~70% (meta-analysis, PMID 15927077); macrolides/cephalosporins are penicillin-allergy alternatives.
  • Penicillin allergy in severe RHD is a specific clinical challenge addressed by a dedicated AHA presidential advisory on desensitization/testing strategies (JAHA 2022).

Anticoagulation (chronic RHD with AF or mechanical valve)

  • Warfarin (CHEBI:10033), target INR 2–3, remains standard for RHD-associated atrial fibrillation — a landmark trial (INVICTUS) established warfarin's superiority over DOACs specifically in RHD-associated AF, a population historically excluded from DOAC trials (NEJM editorial, PMID/DOI 10.1056/NEJMe2210187).
  • Pregnancy-specific management: warfarin crosses the placenta and risks fetal warfarin syndrome (nasal hypoplasia, skeletal abnormalities) in the first trimester; low-molecular-weight heparin (LMWH, dose-adjusted to anti-Xa 0.5–1.0 U/mL) or unfractionated heparin is preferred peripartum, with heparin bridging around delivery and resumption of warfarin postpartum.

Interventional/surgical

  • Percutaneous balloon mitral valvuloplasty (PBMV) — preferred for suitable (non-calcified, non-regurgitant) rheumatic mitral stenosis; less invasive, shorter procedure, lower cost than surgery, with comparable mid-term outcomes in appropriately selected patients; ~20% develop new/worsened mitral regurgitation post-procedure.
  • Mitral valve repair vs. replacement — repair shows greater hemodynamic improvement and short-term clinical efficacy where anatomically feasible; replacement (mechanical or bioprosthetic) is required for more advanced/calcified/regurgitant disease. Mechanical valve replacement carries long-term thromboembolism (~11% cumulative at 25 years in one cohort), intracranial hemorrhage, perivalvular leak, and endocarditis risk requiring lifelong anticoagulation.
  • NCIT candidate treatment terms (verify exact IDs via OAK): NCIT:C15986 Pharmacotherapy (generic anchor for aspirin/NSAID/steroid/penicillin/warfarin, paired with therapeutic_agent); NCIT:C15329 Surgical Procedure (mitral/aortic valve repair or replacement); a balloon-valvuloplasty-specific NCIT term should be looked up directly (not confidently identified in this pass).

Prevention of complications / supportive care

Standard heart-failure pharmacotherapy (diuretics, ACE inhibitors/ARBs, beta-blockers) is used symptomatically for RHD-related heart failure, following general heart-failure guidelines rather than RHD-specific evidence — these represent generic HF pharmacotherapy rather than RHD-mechanism-targeted treatment and should be annotated as treatment_term: NCIT:C15986 Pharmacotherapy with the appropriate agent, not target_mechanisms on the autoimmune valvulitis pathway itself.

Experimental

No RHD-specific advanced therapeutics (gene therapy, cell therapy, targeted immunotherapy) are in clinical development at this time; the major "experimental" frontier is primary prevention via GAS vaccine (§13) rather than disease-modifying treatment of established RHD.

13. Prevention

Primary prevention: prompt antibiotic treatment (penicillin) of confirmed/probable GAS pharyngitis — ~70% reduction in ARF attack rate (PMID 15927077; AHA 2009 statement). Population-level "sore throat management" programs (school-based throat-swab/treat programs) are a core public-health strategy in endemic regions.

Secondary prevention: regular BPG secondary prophylaxis after a confirmed ARF episode, sustained for years (minimum 5, often to age 21+ or longer for those with carditis/RHD) — the single most impactful intervention for preventing RHD progression once ARF has occurred.

Tertiary prevention: infective-endocarditis prophylaxis considerations for high-risk dental/surgical procedures in patients with damaged valves (per current, more restrictive endocarditis-prophylaxis guidelines); anticoagulation to prevent thromboembolic stroke in RHD-associated AF; timely surgical referral to prevent irreversible heart-failure decompensation.

Vaccination (the major prevention frontier): No licensed GAS vaccine currently exists. Active development includes: - Carbohydrate-based (L-rhamnose/group A carbohydrate backbone) candidates designed to raise protective IgG without inducing cross-reactive (cardiac-mimicking) antibody — directly addressing the historical safety concern that a poorly designed GAS vaccine could itself trigger molecular-mimicry-driven carditis (F1000Research/PMC11829149; PMID 39959434). - Peptide-based candidates — phase 1 RCT ongoing/recently completed (est. completion March 2025) (Trials journal, 2024). - IVI universal conjugate vaccine program — proof-of-concept study launched 2024, running through 2027, aiming to select an optimal conjugation platform via animal immunogenicity/efficacy studies (IVI). - WHO R&D Technology Roadmap / Preferred Product Characteristics for GAS vaccines formally guides the development pipeline (Clin Infect Dis 2019, PMID 30624673). - A dedicated cardiac-safety monitoring framework (endorsed by SAVAC/ASAVI) has been developed specifically for early-phase GAS vaccine trials, given the historical precedent of vaccine-associated ARF risk, standardizing echocardiographic + clinical cardiac surveillance (PMID 40450801).

Public health/behavioral interventions: overcrowding reduction, health-system strengthening for GAS pharyngitis diagnosis/treatment access, and community-based ARF/RHD control programs (notably in Aboriginal/Torres Strait Islander Australian communities) — a recent systematic review catalogued Australian RHD-elimination prevention programs and their implementation gaps (Lowitja Journal 2024).

Genetic counseling / risk stratification: not applicable in the classic monogenic sense; population/community-level risk stratification (Indigenous status, remoteness, prior ARF history) drives targeted screening and prophylaxis-program enrollment rather than individual genetic counseling.

14. Other Species / Natural Disease

RHD is, for practical purposes, a human-specific disease — S. pyogenes is essentially a human-adapted pathogen, and there is no well-documented naturally occurring veterinary/wildlife analog of GAS-triggered post-infectious autoimmune carditis. No OMIA (animal Mendelian disease) entry or established veterinary RHD analog was identified in this search. This is a notable contrast to many other cardiovascular/autoimmune diseases in the dismech KB that have companion-animal natural-disease correlates — for RHD, the "other species" content is essentially limited to laboratory-induced models (§15) rather than spontaneous natural disease. No zoonotic transmission concern applies (GAS pharyngitis/ARF pathogenesis is human-host-restricted in practice, notwithstanding rare GAS colonization reports in other mammals).

15. Model Organisms

Lewis rat — the primary, best-validated model (Animal Models review, PMC4220098 / PMID 25414841; AJP epitope-mapping study): - Female Lewis rats (8–12 weeks) immunized subcutaneously with recombinant GAS M5 protein (or M5 peptide) in complete Freund's adjuvant, with Bordetella pertussis as additional adjuvant and a day-7 booster, develop autoimmune valvulitis recapitulating human histopathology. - Outcomes: 75% develop rheumatic-like myocarditis, 62.5% develop chronic valvulitis by 24 weeks post-immunization, with cross-reactive heart-tissue antibodies and T cells, and histological findings including acute damage progressing to fibrosis and vascular neogenesis — closely mirroring the human chronic valve lesion. - Cardiac myosin immunization (rather than M protein) also induces valvulitis in Lewis rats, with the pathogenic epitopes mapped to the myosin rod region, supporting the molecular-mimicry model directly. - An alternative formalin-killed streptococci induction protocol has also been reported to produce chronic rheumatic valvulitis (PMID referenced via search: "An animal model of chronic rheumatic valvulitis induced by formalin-killed streptococci"). - A 2025 Nature Reviews Cardiology commentary describes a "transformative preclinical model" development, suggesting active ongoing refinement of RHD animal modeling as of this reporting period (title only identified; full mechanistic detail not retrieved in this pass — recommend direct follow-up read: Nat Rev Cardiol 2025).

Model limitations: Rodent models require artificial immunization (adjuvant-driven) rather than natural GAS mucosal infection, so they model the downstream autoimmune effector phase well but do not fully recapitulate the natural infection-to-autoimmunity transition, repeated-exposure/recurrence biology, or the human HLA-restricted antigen-presentation context (rat MHC, not human HLA, governs susceptibility in these models) — a genuine human-model-fidelity gap worth flagging explicitly if curated (candidate for a HUMAN_MODEL_MISMATCH discussion given rat MHC vs. human HLA-restricted epitope presentation, and adjuvant-driven vs. natural-infection induction).

Research applications: Lewis rat valvulitis models are used to dissect molecular-mimicry epitope specificity (M-protein vs. myosin vs. other candidate antigens), test candidate GAS vaccine constructs for cardiac cross-reactivity/safety (a major use case given the vaccine-safety concerns noted in §13), and study T-cell/antibody effector mechanisms of valve damage.

Other model systems: No robust zebrafish, Drosophila, C. elegans, or iPSC-organoid RHD model was identified in this search — the field remains centered on the Lewis rat immunization paradigm, with in vitro human valve endothelial/interstitial cell cross-reactivity assays as a complementary (non-whole-organism) system for mechanism dissection.

Summary Table — Suggested Ontology Term Anchors (verify all before curation)

Domain Suggested term Confidence
Organism/pathogen NCBITaxon:1314 (Streptococcus pyogenes) High
Phenotype HP:0001653 (mitral regurgitation), HP:0001718 (mitral stenosis), HP:0001659 (aortic regurgitation), HP:0001650 (aortic valve stenosis), HP:0002072 (chorea), HP:0001369 (arthritis), HP:0001482 (subcutaneous nodule), HP:0005110 (atrial fibrillation), HP:0001635 (heart failure) Moderate–high; verify labels via OAK
Anatomy UBERON heart valve / mitral valve / aortic valve terms, UBERON:0000165 (pharynx), UBERON:0000980 (synovial joint) Moderate; verify exact CURIEs
Cell types CL:0000624 (CD4+ T cell), CL:0000235 (macrophage), CL:0000786 (plasma cell), CL:0000057 (fibroblast) Moderate
Genes HLA-DRB1, HLA-DQA1, HLA-DQB1, IGHV4-61, MYH6, VIM, ADRB1 Moderate; HLA CURIE convention needs confirmation
Chemicals/drugs CHEBI:15365 (aspirin), CHEBI:7476 (naproxen), CHEBI:8382 (prednisone), CHEBI:10033 (warfarin) High for common drugs; verify benzathine penicillin G CURIE
Treatment action NCIT:C15986 (Pharmacotherapy), NCIT:C15329 (Surgical Procedure) High for generic anchors; verify any procedure-specific NCIT code
ICD-10-CM I00–I02 (acute rheumatic fever), I05–I09 (chronic RHD) High

Sources