Mitral regurgitation in the elderly

Definition and classification. Mitral regurgitation (MR) is systolic backflow from the left ventricle into the left atrium through an incompetent mitral valve. Classify as PRIMARY (degenerative/organic) — a structural abnormality of the leaflets, chordae or annulus, versus SECONDARY (functional) — a structurally normal valve failing because of left ventricular or left atrial remodelling. This distinction determines the entire management pathway. Also classify by acute versus chronic.

Causes in older adults. Primary: mucoid (myxomatous) degeneration with mitral valve prolapse — mucoid degeneration affects mainly the mitral valve, allowing the leaflet to stretch under normal intracardiac pressure and prolapse into the left atrium in systole; it is found in about 1% of autopsies over the age of 65. Also mitral annular calcification, a disease of older adults found in 9% of autopsies over 50, rising strikingly with age and particularly in women — from 3.2% under 70 to 44% over 90 — which often results in mitral insufficiency or conduction abnormalities and rarely stenosis, is an important contributor to congestive heart failure in older adults, and is a site for endocarditis. Other primary causes: infective endocarditis, rheumatic disease (important in India), and chordal rupture, which is the usual mechanism of death directly from mucoid degeneration. Secondary: ischaemic MR after myocardial infarction, dilated cardiomyopathy, and atrial functional MR from long-standing atrial fibrillation with left atrial and annular dilatation — increasingly recognised as a distinct and common entity in the very old.

Clinical features. Chronic MR is often long asymptomatic, then presents with exertional dyspnoea, fatigue, orthostatic intolerance, palpitations and atrial fibrillation, and finally with pulmonary hypertension and right heart failure. Acute severe MR — from papillary muscle rupture after myocardial infarction or from endocarditis — presents as abrupt pulmonary oedema and cardiogenic shock, often with only a soft or absent murmur because atrial and ventricular pressures rapidly equalise. Signs of chronic MR: a pansystolic murmur at the apex radiating to the axilla, a soft S1, a third heart sound, a displaced hyperdynamic apex beat and, in mitral valve prolapse, a mid-systolic click with a late systolic murmur — though the murmur of prolapse can occur at any time in systole. Distinguishing features on manoeuvres: the murmur of mitral regurgitation does NOT increase after a premature ventricular contraction and decreases with amyl nitrite and Valsalva, unlike the aortic murmurs. Mitral insufficiency caused by mucoid degeneration is usually well tolerated and rarely requires surgery; with mitral annular calcification the regurgitation is usually mild to moderate, and as many as two-thirds of patients with mitral annular calcification present with an apical systolic murmur of mitral regurgitation.

Investigations. Echocardiography is the best technique for diagnosing mitral annular calcification and for assessing MR overall — it defines the mechanism, severity (regurgitant volume, effective regurgitant orifice area, vena contracta), left ventricular size and ejection fraction, left atrial size and pulmonary artery pressure. Transoesophageal echocardiography is used to define anatomy before intervention and to detect endocarditis. Add ECG (atrial fibrillation, left atrial enlargement, conduction abnormality with annular calcification), chest radiograph, BNP, exercise echocardiography for exertional symptoms with apparently moderate MR, and coronary angiography before surgery. In severe chronic MR the ejection fraction is spuriously flattered by the low-impedance leak, so an EF below 60% already indicates significant left ventricular dysfunction.

Management. Acute severe MR is a surgical emergency: stabilise with afterload reduction (nitroprusside), diuretics and an intra-aortic balloon pump if hypotensive, and proceed to urgent surgery. Chronic primary MR: there is no medical therapy that alters the natural history — surgery (mitral valve repair in preference to replacement) is indicated for symptomatic severe MR, or for asymptomatic severe MR with an ejection fraction ≤ 60%, an end-systolic diameter ≥ 40 mm, new atrial fibrillation or pulmonary hypertension. Chronic secondary MR: the first step is optimal guideline-directed heart failure therapy plus cardiac resynchronisation and revascularisation where indicated, because functional MR frequently improves with successful treatment of the ventricle. Surgery is indicated only after this has failed, and there is a well-established survival benefit from correcting coexistent moderate or greater ischaemic mitral regurgitation at the time of CABG surgery. Additional geriatric points: anticoagulate for atrial fibrillation; note that mitral annular calcification carries a higher incidence of cerebral embolism, so anticoagulation with warfarin may be indicated; surgery for annular calcification is usually indicated only if endocarditis is superimposed; and a bioprosthesis is preferred over 70 years for a valve in the mitral position. Subacute bacterial endocarditis prophylaxis is no longer recommended for mitral valve prolapse.

Transcatheter edge-to-edge repair (TEER, "MitraClip") is now established for older patients who are unsuitable for surgery. Building on COAPT, two 2024 randomised trials in secondary MR with heart failure — RESHAPE-HF2 and MATTERHORN (both NEJM 2024) — showed that TEER added to guideline-directed medical therapy reduced heart failure hospitalisation and improved symptoms and quality of life, with MATTERHORN additionally showing non-inferiority to surgery for the composite of death, hospitalisation, reintervention and assist device implantation, but with significantly fewer major adverse events. Because it is performed percutaneously without cardiopulmonary bypass, TEER is especially attractive in the frail elderly, and current ACC/AHA and ESC valve guidance recommends it for appropriately selected patients with severe symptomatic MR at high or prohibitive surgical risk, after Heart Team assessment.