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Rheumatic fever notes for MBBs

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Acute Rheumatic Fever (ARF) - MBBS Notes

Definition

Acute rheumatic fever is a delayed, immune-mediated, non-suppurative inflammatory complication occurring about 2-4 weeks after an untreated or inadequately treated Group A beta-hemolytic Streptococcus (GAS), Streptococcus pyogenes pharyngitis.
It predominantly affects children aged 5-15 years and may cause permanent valvular heart disease, termed rheumatic heart disease (RHD).

Etiopathogenesis

  • Trigger: Pharyngeal infection with rheumatogenic strains of GAS.
  • It follows pharyngitis, not streptococcal skin infection.
  • Antibodies and T cells formed against streptococcal M-protein cross-react with host tissues due to molecular mimicry.
  • Involved tissues:
    • Heart: myocardium, endocardium, pericardium
    • Joints
    • Skin
    • Central nervous system

Pathology

The characteristic lesion in rheumatic carditis is the Aschoff body:
  • Focal granulomatous inflammation with fibrinoid necrosis
  • Contains macrophages called Anitschkow cells with caterpillar-shaped nuclei
  • May be seen in all three layers of the heart in pancarditis.

Clinical Features

Usually occur 2-4 weeks after sore throat.

Major manifestations

  1. Carditis / valvulitis
  2. Migratory polyarthritis
  3. Sydenham chorea
  4. Erythema marginatum
  5. Subcutaneous nodules

Minor manifestations

  • Fever
  • Arthralgia
  • Raised ESR and/or CRP
  • Prolonged PR interval on ECG

Diagnosis: Revised Jones Criteria

Diagnosis requires evidence of preceding GAS infection plus either:
  • Two major criteria, OR
  • One major and two minor criteria

Evidence of preceding GAS infection

Any one of:
  • Positive throat culture for GAS
  • Positive rapid streptococcal antigen test
  • Raised or rising antistreptolysin O titre (ASO)
  • Raised anti-DNase B titre
  • Recent scarlet fever
Chorea alone or indolent carditis may be diagnosed as ARF even when evidence of recent streptococcal infection is absent.

Jones criteria table

Major criteriaMinor criteria
Carditis, clinical or subclinicalFever
Migratory polyarthritisArthralgia
Sydenham choreaElevated ESR or CRP
Erythema marginatumProlonged PR interval
Subcutaneous nodules

Important point

In moderate- or high-risk populations, monoarthritis, polyarthralgia, and sometimes aseptic monoarthritis may qualify differently under risk-based Jones criteria.

Major Manifestations

1. Carditis

The most serious manifestation, occurring in about 50-70% of patients. It usually presents as pancarditis, but valvulitis is the clinically important component.

Valvular involvement

  • Mitral valve is most commonly affected.
  • Acute lesion: mitral regurgitation.
  • Aortic regurgitation may coexist.
  • Chronic disease commonly causes mitral stenosis, with or without mitral regurgitation.

Features

  • Tachycardia disproportionate to fever
  • New murmur:
    • Pansystolic apical murmur radiating to axilla: mitral regurgitation
    • Early diastolic decrescendo murmur: aortic regurgitation
  • Cardiomegaly
  • Pericardial rub or effusion
  • Heart failure
  • Carey Coombs murmur: mid-diastolic apical murmur due to active mitral valvulitis, not mitral stenosis.

Investigations

  • ECG: PR prolongation, arrhythmia
  • Chest X-ray: cardiomegaly, pulmonary congestion
  • Echocardiography with Doppler: detects clinical and subclinical carditis, valvular regurgitation, ventricular function, and pericardial effusion.

2. Migratory Polyarthritis

  • Commonly affects large joints:
    • Knees
    • Ankles
    • Elbows
    • Wrists
  • Typical features:
    • Painful, swollen, warm joints
    • Migratory pattern: resolves in one joint and appears in another
    • Asymmetric
    • Dramatic response to salicylates or NSAIDs
    • Does not cause permanent joint deformity

3. Sydenham Chorea

A late manifestation, often appearing weeks to months after streptococcal infection. It may occur alone.

Features

  • Rapid, purposeless, irregular involuntary movements
  • Emotional lability
  • Hypotonia
  • Clumsiness and deteriorating handwriting
  • Facial grimacing
  • Milkmaid's grip: irregular squeezing of examiner's fingers
  • Pronator sign: pronation of hands when arms are extended
  • May be unilateral, termed hemichorea
Chorea usually resolves spontaneously, but it may last several months.

4. Erythema Marginatum

  • Rare, evanescent, non-pruritic rash
  • Pink macules or serpiginous rings with central clearing
  • Mainly over trunk and proximal limbs
  • Spares face
  • More visible with warmth

5. Subcutaneous Nodules

  • Small, firm, painless, mobile nodules
  • Located over extensor surfaces and bony prominences:
    • Elbows
    • Knees
    • Wrists
    • Occiput
    • Spine
  • Usually associated with severe carditis.

Investigations

To demonstrate inflammation

  • ESR: elevated
  • CRP: elevated
  • CBC: leukocytosis may be present

To prove recent GAS infection

  • ASO titre
  • Anti-DNase B titre
  • Throat swab culture
  • Rapid antigen detection test

Cardiac assessment

  • ECG: prolonged PR interval, rhythm abnormalities
  • Echocardiography with Doppler: mandatory where available
  • Chest X-ray: cardiac enlargement or pulmonary edema in heart failure

Treatment

Management has four components:
  1. Eradicate streptococcal infection
  2. Control inflammation and symptoms
  3. Treat carditis and heart failure
  4. Prevent recurrence with secondary prophylaxis

1. Eradication of GAS

Even if throat culture is negative, give antibiotics once ARF is diagnosed.

Preferred regimen

  • Benzathine penicillin G, intramuscular single dose
    • <27 kg: 600,000 units IM
    • ≥27 kg: 1.2 million units IM

Alternatives

  • Penicillin V orally for 10 days
  • Amoxicillin orally for 10 days
  • If penicillin allergy: macrolide such as azithromycin, guided by local resistance patterns

2. Anti-inflammatory treatment

Arthritis without carditis

  • Aspirin or an NSAID such as naproxen.
  • Symptoms generally improve rapidly.

Carditis

  • Mild carditis: NSAIDs may be used for symptomatic inflammatory control.
  • Moderate or severe carditis, especially with heart failure: corticosteroids may be considered in specialist care.
  • Anti-inflammatory medicines improve symptoms but do not reliably prevent chronic valvular disease.

3. Treatment of heart failure

If carditis produces heart failure:
  • Bed rest and monitoring
  • Salt restriction
  • Diuretics, such as furosemide
  • ACE inhibitor if appropriate
  • Digoxin may be considered cautiously in selected cases
  • Manage severe valvular regurgitation with cardiology input

4. Management of Sydenham chorea

  • Rest and reassurance
  • Avoid situations where involuntary movements may cause injury
  • Severe disabling chorea may be treated with:
    • Sodium valproate
    • Carbamazepine
    • Haloperidol in selected cases
    • Corticosteroids may be considered in severe cases

Secondary Prophylaxis

Secondary prophylaxis prevents recurrent ARF and progression of rheumatic heart disease.

Preferred regimen

Benzathine penicillin G IM every 3-4 weeks
  • <27 kg: 600,000 units
  • ≥27 kg: 1.2 million units
Three-weekly dosing is often preferred in high-risk settings or after recurrence despite four-weekly prophylaxis.

Duration of prophylaxis

Clinical situationDuration
ARF without carditis5 years after last attack or until age 21 years, whichever is longer
ARF with carditis but no residual valvular disease10 years after last attack or until age 21 years, whichever is longer
ARF with residual valvular diseaseAt least 10 years after last attack or until age 40 years, whichever is longer
Severe valvular disease / valve surgeryOften lifelong, based on cardiology advice

Complications

Acute

  • Congestive cardiac failure
  • Pericardial effusion
  • Arrhythmias

Chronic

  • Rheumatic heart disease
  • Mitral stenosis
  • Mitral regurgitation
  • Aortic valve disease
  • Atrial fibrillation
  • Left atrial thrombus and systemic embolism
  • Pulmonary hypertension
  • Infective endocarditis risk in damaged valves

Differential Diagnosis

Polyarthritis

  • Septic arthritis
  • Juvenile idiopathic arthritis
  • Systemic lupus erythematosus
  • Viral arthritis
  • Reactive arthritis

Carditis

  • Viral myocarditis
  • Infective endocarditis
  • Congenital heart disease
  • Kawasaki disease

Chorea

  • Wilson disease
  • Drug-induced chorea
  • Systemic lupus erythematosus
  • Huntington disease, though uncommon in childhood

Prevention

Primary prevention

Prompt diagnosis and adequate antibiotic treatment of GAS pharyngitis prevents the first attack of ARF.

Secondary prevention

Long-term penicillin prophylaxis in anyone with prior ARF, especially those with carditis or established RHD.

Exam Pearls

  • ARF follows GAS pharyngitis, not impetigo.
  • The commonest major manifestation is migratory polyarthritis.
  • The most important manifestation prognostically is carditis.
  • The commonest valve involved is the mitral valve.
  • Acute rheumatic carditis commonly produces mitral regurgitation.
  • Chronic rheumatic heart disease most classically produces mitral stenosis.
  • Histological hallmark: Aschoff bodies with Anitschkow cells.
  • Diagnosis: evidence of recent GAS infection plus 2 major or 1 major + 2 minor Jones criteria.
  • Echocardiography can detect subclinical carditis.
  • Long-term benzathine penicillin prophylaxis is central to preventing recurrence and chronic valve damage.
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