Rheumatic Mitral Regurgitation

Backflow through the mitral valve caused by rheumatic damage: leaflet thickening and retraction, chordal shortening and fusion, and annular dilatation. In acute rheumatic carditis, annulitis and chordal elongation or rupture cause leaflet prolapse and acute regurgitation.

• Rheumatic heart disease affects about 40 million people and causes about 300,000 deaths a year, mostly in sub-Saharan Africa, South Asia and the Pacific. Echocardiographic screening finds a few cases per 1000 children in endemic regions (up to about 30 per 1000 in some settings), many without a history of rheumatic fever.
• Mechanism: group A streptococcal throat infection triggers an immune response against cardiac tissue by molecular mimicry, and repeated attacks produce progressive fibrosis. Regurgitation is the commonest lesion in acute rheumatic fever and in children; mixed regurgitation and stenosis is common in adults.
• Consequences: left atrial dilatation and atrial fibrillation, left ventricular volume overload with dilatation and dysfunction, pulmonary hypertension, heart failure, stroke and endocarditis.

• Chronic: asymptomatic for years, then fatigue, exertional dyspnoea, orthopnoea, palpitations (atrial fibrillation), oedema. Acute severe regurgitation: pulmonary oedema.
• Signs: displaced, hyperdynamic apex, soft first heart sound, apical pansystolic murmur radiating to the axilla, S3, loud pulmonary second sound with pulmonary hypertension, irregular pulse in atrial fibrillation. In acute carditis: tachycardia out of proportion to fever, pericardial rub, and a soft mid-diastolic apical murmur (Carey Coombs murmur).
• Rheumatic fever features: fever, migratory polyarthritis, chorea, erythema marginatum, subcutaneous nodules, raised CRP and ESR, prolonged PR interval, and evidence of recent streptococcal infection.
• Differential diagnosis: mitral valve prolapse (myxomatous), ischaemic mitral regurgitation, functional regurgitation in dilated cardiomyopathy, infective endocarditis, mitral annular calcification, congenital cleft valve, hypertrophic cardiomyopathy with systolic anterior motion, papillary muscle rupture, and drug induced valve disease (ergot, dopamine agonists).
• Complications: heart failure, atrial fibrillation with thromboembolism, pulmonary hypertension, infective endocarditis, left ventricular dysfunction, and recurrent rheumatic fever with progressive damage.

• ECG: P mitrale or atrial fibrillation, left ventricular hypertrophy, and prolonged PR interval in carditis. Chest X-ray: left atrial enlargement, cardiomegaly, pulmonary congestion.
• Echocardiography: thickened, restricted posterior leaflet (restricted leaflet motion), shortened chordae, annular dilatation, and the regurgitant jet direction. Severe regurgitation: vena contracta 0.7 cm or more, effective regurgitant orifice area 0.4 cm2 or more, regurgitant volume 60 mL or more, regurgitant fraction 50% or more, pulmonary vein systolic flow reversal. Left ventricular end systolic diameter greater than 40 mm or ejection fraction 60% or less signals left ventricular decompensation; pulmonary systolic pressure greater than 50 mmHg is significant.
• Transoesophageal echocardiography for mechanism and repair planning; cardiac MRI for quantification when echocardiography is discordant.
• Blood tests in suspected acute rheumatic fever: throat swab culture, antistreptolysin O titre and anti-DNase B, CRP, ESR, blood cultures if febrile (exclude endocarditis), HIV test.

• Prevent progression and recurrent attacks.
• Acute rheumatic fever:
  • Benzathine benzylpenicillin 1.2 million units IM once (600,000 units if under 30 kg), or penicillin V 500 mg orally twice daily for 10 days (250 mg for children).
  • Aspirin 75 to 100 mg/kg/day in 4 divided doses for children (adults 4 to 8 g/day in divided doses) for arthritis, for 1 to 2 weeks then taper over 4 to 6 weeks; monitor for salicylate toxicity.
  • Carditis with heart failure: prednisolone 1 to 2 mg/kg/day (maximum 80 mg) for 2 to 3 weeks, then taper over 2 to 4 weeks; diuretics; ramipril 1.25 to 5 mg daily.
  • Chorea: carbamazepine 7 to 20 mg/kg/day in 2 to 3 divided doses, or sodium valproate 15 to 20 mg/kg/day; bed rest and a calm environment.
• Secondary prophylaxis (essential to stop progression):
  • Benzathine benzylpenicillin 1.2 million units IM every 3 to 4 weeks (600,000 units if under 30 kg); every 3 weeks in high risk patients.
  • Penicillin V 250 mg orally twice daily is an alternative; sulfadiazine 1 g daily (500 mg if under 30 kg) or erythromycin 250 mg twice daily for penicillin allergy.
  • Duration: without carditis, 5 years after the last attack or to age 21, whichever is longer; with carditis but no residual valve disease, 10 years or to age 21; with persistent valve disease, 10 years or to age 40, whichever is longer, sometimes for life.
• Symptomatic and chronic therapy:
  • Furosemide 20 to 80 mg daily for congestion; ramipril 1.25 to 10 mg daily for heart failure or hypertension.
  • Bisoprolol 1.25 to 10 mg daily for heart failure or rate control in atrial fibrillation; digoxin 0.125 to 0.25 mg daily.
  • Atrial fibrillation: warfarin to INR 2.0 to 3.0; direct oral anticoagulants are not advised when moderate or severe mitral stenosis coexists, and evidence in pure rheumatic regurgitation is limited.
  • Infective endocarditis prophylaxis only after valve replacement or previous endocarditis: amoxicillin 2 g orally (50 mg/kg in children) 30 to 60 minutes before dental procedures; azithromycin or clarithromycin 500 mg (15 mg/kg in children) if allergic to penicillin (clindamycin is no longer recommended).
• Surgery:
  • Indications: symptomatic severe regurgitation; asymptomatic severe regurgitation with ejection fraction 30 to 60% or end systolic diameter 40 mm or more, new atrial fibrillation, or pulmonary systolic pressure greater than 50 mmHg.
  • Repair is preferred (annuloplasty ring, leaflet extension with pericardial patch, chordal transfer), though repair is less durable in rheumatic than in degenerative disease (about 70 to 80% free from reoperation at 10 years). Preserve the subvalvular apparatus if replacing the valve.
  • Replacement: mechanical valve in younger patients (warfarin to INR 3.0, range 2.5 to 3.5 for a mitral valve); bioprosthesis in patients over 65 or unable to take warfarin (it degenerates quickly in young patients).
  • Operative mortality about 1 to 3% for repair and 3 to 8% for replacement. Percutaneous edge-to-edge repair has limited evidence in rheumatic valves because of restricted, thickened leaflets.
• Special groups:
  • Pregnancy: mild or moderate regurgitation is usually tolerated; furosemide for congestion; metoprolol for rate control; avoid ACE inhibitors and ARBs. Maintain secondary prophylaxis with penicillin. Mechanical valves need specialist anticoagulation planning (enoxaparin 1 mg/kg twice daily with anti-Xa monitoring, or warfarin at a dose of 5 mg or less per day, with expert advice).
  • Children: secondary prophylaxis, early echocardiographic follow up, and early repair rather than replacement.
  • Elderly: bioprosthetic replacement; avoid prolonged bypass in frail patients.
  • HIV: antiretroviral therapy; no change in penicillin prophylaxis.
• Red flags: acute pulmonary oedema, new atrial fibrillation or embolism, fever with a new murmur, syncope, rapid ventricular dilatation, missed prophylaxis injections.
• Follow up: severe asymptomatic regurgitation every 6 months with echocardiography; moderate every year; mild every 1 to 2 years. Screen household contacts with echocardiography in endemic areas.