Mitral Regurgitation

Mitral regurgitation (MR) is systolic backflow from the left ventricle into the left atrium.

Primary (degenerative) MR: myxomatous disease, prolapse, flail leaflet (chordal rupture), endocarditis, rheumatic disease, cleft leaflet.

Secondary (functional) MR: left ventricular dilatation or ischaemic remodelling with leaflet tethering, or atrial functional MR in atrial fibrillation and HFpEF.

Acute MR: papillary muscle rupture, endocarditis, chordal rupture.

Severe MR: vena contracta 7 mm or more, effective regurgitant orifice 0.4 cm2 or more (0.2 in secondary), regurgitant volume 60 mL or more, pulmonary vein flow reversal.

Complications: atrial fibrillation, left ventricular dysfunction, pulmonary hypertension, heart failure, endocarditis, sudden death in flail leaflets.

• Chronic: asymptomatic for years, then dyspnoea, fatigue, palpitations.
• Holosystolic apical murmur radiating to the axilla, soft S1, S3, displaced apex; late systolic murmur with click in prolapse; eccentric jets mimic other murmurs.
• Acute: pulmonary oedema and shock, soft murmur.

• Echocardiography (transthoracic and transoesophageal): mechanism, severity, ventricular size and function (end systolic diameter over 40 mm, ejection fraction 60% or less indicate dysfunction), pulmonary pressure, repair feasibility.
• Cardiac MRI for quantification in doubtful cases.
• Exercise echo in asymptomatic patients with equivocal severity.
• Coronary angiography before surgery; BNP; Holter for arrhythmia.

Primary MR

• Surgery indications: symptoms; asymptomatic with ejection fraction 60% or less, end systolic diameter 40 mm or more, new atrial fibrillation, pulmonary systolic pressure over 50 mmHg, flail leaflet with high repair likelihood.
• Mitral valve repair preferred (over 95% feasible in posterior prolapse) over replacement. Mechanical prosthesis needs warfarin; bioprosthesis.
• Transcatheter edge to edge repair (MitraClip, PASCAL) for high surgical risk.
• Medical: diuretics, vasodilators (limited role); anticoagulation for atrial fibrillation.

Secondary MR

• Optimise guideline directed heart failure therapy first (sacubitril/valsartan, beta blocker, MRA, SGLT2 inhibitor), CRT if indicated, revascularisation.
• Persisting severe symptomatic MR with ejection fraction 20 to 50% and appropriate anatomy: transcatheter edge to edge repair (COAPT: reduced hospitalisation and mortality).
• Surgery during coronary bypass for severe MR.

Acute MR

Afterload reduction (sodium nitroprusside 0.25 to 0.5 micrograms/kg/min), diuretics, inotropes, IABP; urgent surgery.

Follow up

Echo every 6 to 12 months for severe asymptomatic disease; endocarditis prophylaxis after prosthetic repair; dental care.