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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
Key points
- MR = systolic backflow through mitral valve → LA dilatation → AF, pulmonary congestion, and eventual LV failure
- Primary (organic): MVP, rheumatic, endocarditis, chordal rupture. Secondary (functional): LV dilatation from ischaemic or dilated cardiomyopathy
- Pansystolic murmur at apex, radiating to axilla, best heard in left lateral position
- Acute MR (chordal rupture, post-MI papillary muscle rupture) = surgical emergency with flash pulmonary oedema
- Surgery: valve repair preferred over replacement (better long-term outcomes); transcatheter edge-to-edge repair (MitraClip) for high surgical risk
Overview
Mitral regurgitation (MR) is the backward flow of blood from the left ventricle into the left atrium during systole due to incomplete closure of the mitral valve. It is classified as primary (intrinsic valve disease) or secondary/functional (normal valve with distorted geometry from LV dilatation). Mitral valve prolapse (MVP) is the commonest cause of primary MR in the developed world. Chronic MR is often well tolerated for years until LV decompensation occurs. Acute severe MR (e.g. chordal rupture, post-MI papillary muscle rupture) is a surgical emergency.
Epidemiology
MR is the most common valvular heart disease by prevalence, with moderate-to-severe MR affecting approximately 2% of the general population. MVP affects 2–3% of the population, predominantly women, and is the commonest cause of primary MR in the UK. Secondary MR is seen in up to 50% of patients with heart failure with reduced ejection fraction. Rheumatic MR remains prevalent in low-income settings.
Clinical Features
Symptoms
Chronic MR may be asymptomatic for many years
Exertional dyspnoea (progressive)
Fatigue and reduced exercise tolerance
Palpitations (AF)
Acute MR: sudden severe dyspnoea, flash pulmonary oedema
Orthopnoea and PND
Signs
Pansystolic murmur at apex, radiating to axilla — louder in left lateral decubitus position
Displaced, hyperdynamic apex beat (volume overload)
Soft S1 (incomplete valve closure)
S3 (rapid ventricular filling in severe MR)
MVP: mid-systolic click followed by late systolic murmur
AF (irregularly irregular pulse)
Signs of pulmonary congestion and right heart failure in severe cases
Investigations
First-line
TTEAssess mechanism (primary vs secondary), severity (regurgitant volume, EROA, vena contracta), LA size, LV dimensions and LVEF
ECGP mitrale (bifid P waves — LA enlargement), AF, LVH
Second-line
Chest X-rayLA enlargement (double shadow, straightened left heart border), cardiomegaly, pulmonary congestion
TOE (transoesophageal echo)Superior detail of valve anatomy — essential for surgical planning, especially repair feasibility
Specialist
Cardiac MRIAccurate regurgitant volume quantification when echo is equivocal
Coronary angiographyPre-operative assessment to exclude coexisting CAD
1
Medical management
- Heart failure treatment for symptomatic patients awaiting surgery (ACEi, beta-blocker, diuretics)
- Anticoagulation if AF present (DOAC or warfarin)
- Secondary MR: optimise HF therapy (may reduce functional MR significantly)
2
Surgical intervention — primary MR
- Symptomatic severe primary MR → surgery (repair preferred over replacement)
- Asymptomatic severe MR with LVEF ≤60% or LVESD ≥40 mm → consider surgery
- Valve repair is preferred when feasible — superior long-term outcomes, lower thromboembolic risk, avoids anticoagulation
3
Intervention for secondary MR
- Optimise medical therapy first (ACEi, beta-blocker, MRA, SGLT2i, CRT if indicated)
- Transcatheter edge-to-edge repair (MitraClip) may be considered for severe secondary MR with persistent symptoms despite optimal medical therapy
- Mitral valve surgery at time of CABG if severe MR and undergoing revascularisation
4
Acute severe MR
- Urgent surgical intervention
- Stabilise with vasodilators (reduce afterload), IABP if needed, diuretics for pulmonary oedema
Complications
- Atrial fibrillation: LA dilatation → AF → increased stroke risk
- Pulmonary hypertension: Chronic LA pressure elevation → pulmonary venous hypertension
- Heart failure: Progressive LV volume overload → systolic dysfunction
- Infective endocarditis: Particularly MVP with MR
- Thromboembolism: LA stasis, especially with AF
UKMLA Exam Tips
- 1Pansystolic murmur at apex radiating to axilla = MR — distinguish from VSD (pansystolic at left sternal edge) and TR (pansystolic at left lower sternal edge, louder on inspiration)
- 2MVP mid-systolic click + late systolic murmur — murmur gets longer and click moves earlier with standing/Valsalva (reduced preload)
- 3Post-MI new pansystolic murmur + acute pulmonary oedema = think papillary muscle rupture → urgent surgery
- 4Repair is better than replacement — classic exam question on surgical approach to primary MR
- 5Secondary MR from DCM/ischaemic cardiomyopathy → treat the heart failure first; surgery for the MR is second-line
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