Mitral Regurgitation

Meet the patient

A 62-year-old man is admitted at 3am, four days after an inferior STEMI that was stented without complication. He has woken gasping for air, coughing pink froth. His blood pressure is 96/60, he is cold and clammy, and his oxygen saturations are 84 percent on room air.[1]

The registrar listens carefully at the apex and hears... almost nothing. A faint, short murmur, easily missed. The chest is full of crackles to the apices. The instinct is to reach for furosemide and label this "left ventricular failure" — and that instinct is how patients die.[1]

The exam question hiding in this bed is acute severe mitral regurgitation from papillary muscle rupture, and the reason the murmur is soft is that the LA and LV pressures have already equalised. Everything below exists to make you reach for the echo before the diuretic, and to know when chronic MR must be operated before the ventricle fails.[1][3]

What MR is — and why the same murmur is two different diseases

Mitral regurgitation is the backward flow of blood from the left ventricle into the left atrium during systole through an incompetent mitral valve. It is the commonest organic valvular lesion in adults in the developed world after aortic sclerosis, and its prevalence rises steeply with age as degenerative and functional disease accumulate.[1]

The conceptual skill in MR is to recognise that the same murmur and the same echo grading describe two very different diseases:[2]

• Chronic MR — a slow, compensated remodelling illness in which the LA and LV dilate for years before symptoms. The danger is operating too late (irreversible LV dysfunction), hence surgery is recommended for asymptomatic severe primary MR once LV size or function crosses thresholds.
• Acute MR — a haemodynamic emergency (papillary muscle or chordal rupture) with no time for compensation: a small, stiff LA is suddenly overloaded, LA pressure spikes, and the patient presents in cardiogenic shock and pulmonary oedema.[1]

The mitral valve is not just two leaflets — it is an apparatus of leaflets (anterior and posterior, each with three scallops — anterolateral A1/A2/A3, posterolateral P1/P2/P3), the annulus (a dynamic saddle-shaped fibrous ring), chordae tendineae (primary, secondary and tertiary), papillary muscles (anterolateral and posteromedial) and the underlying LV myocardium. Failure of any one component can produce MR, which is why the differential of causes is broad and a structured mechanistic classification is essential.[1]

Classification — Carpentier is the mechanistic map examiners want

MR is classified three overlapping ways — by mechanism (Carpentier), by aetiology (primary versus secondary), and by time-course (acute versus chronic). All three must be answerable in a viva.[1]

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The Carpentier functional classification — the mechanistic map to reproduce verbatim:[1][2]

• Type I — normal leaflet motion. The leaflets move normally but leak because of annular dilation (functional, LV dilation), leaflet perforation (endocarditis) or a cleft (congenital).
• Type II — excess leaflet motion (prolapse or flail). The leaflet edge overrides the annular plane in systole. Classic of degenerative disease and MVP and chordal rupture. Usually affects the posterior leaflet (P2 scallop).
• Type IIIa — restricted leaflet motion in BOTH diastole and systole. Rheumatic (leaflet thickening, commissural fusion, chordal shortening), radiation, carcinoid, SLE (Libman-Sacks).
• Type IIIb — restricted leaflet motion in SYSTOLE only. The classic ischaemic or functional pattern — the leaflets are tethered by a dilated, spherical LV pulling the papillary muscles apically and laterally.[1]

Time-course:[1]

• Chronic — compensated (asymptomatic) for years, then decompensated. Causes: degenerative or MVP, rheumatic, functional, annular calcification.
• Acute — hours to days; no compensatory remodelling. Causes: papillary muscle rupture post-MI, chordal rupture (MVP, trauma, spontaneous), leaflet perforation (endocarditis), prosthetic valve dysfunction, blunt chest trauma, acute ischaemic papillary muscle dysfunction, acute rheumatic.[1]

Causes — split acute from chronic, because the tempo decides the pathway

The aetiology table is the single most tested item in an MR viva, because the tempo dictates the entire management pathway. Separate acute from chronic causes in your answer.[1]

Acute causes (hours to days — surgical emergency)

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Papillary muscle rupture post-MI is the archetype. It occurs in 1 to 2 percent of acute MIs, typically 2 to 7 days after infarction, and almost always involves the posteromedial papillary muscle — it has a single blood supply (the posterior descending artery), versus the dual LAD and circumflex supply of the anterolateral muscle. Partial rupture produces severe but survivable MR; complete rupture is usually fatal within hours without surgery. Operative mortality is high (25 to 40 percent) but surgery is the only chance of survival.[1]

Chordae tendineae rupture occurs spontaneously in myxomatous MVP (especially Barlow disease with multiple flail segments), with trauma, with infective endocarditis, and rarely as the presenting feature of a connective-tissue disorder. The result is an acute flail leaflet with sudden severe MR.[1]

Infective endocarditis causes MR through a vegetation preventing coaptation, leaflet perforation, chordal rupture, or abscess with annular destruction. Acute severe MR in IE is an indication for emergency surgery.[1]

Prosthetic valve dysfunction — thrombosis of a mechanical valve, dehiscence of a suture ring, structural deterioration of a bioprosthesis, or a stuck leaflet in a bileaflet mechanical valve — produces acute or subacute MR and is a surgical or transcatheter emergency.[1]

Blunt chest trauma (road traffic collisions, falls, CPR) can avulse chordae or a papillary muscle head, producing acute MR days to weeks after the injury; a careful history is decisive.[1]

Chronic causes (years — watchful timing)

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Degenerative (myxomatous) MR is the commonest cause of chronic primary MR in the developed world (60 to 70 percent), and divides into two pathologies examiners contrast: Barlow disease (younger patients, diffuse myxomatous change, thick redundant billowing leaflets, multiple prolapsing segments, complex repair) and fibroelastic deficiency (older patients, thin translucent leaflets with a single flail segment, usually P2, a straightforward durable repair). The distinction predicts surgical complexity and repairability.[1]

Rheumatic MR remains the commonest cause worldwide. Rheumatic carditis produces leaflet thickening, commissural fusion, chordal shortening and calcification — usually a mixed MS plus MR picture. The annulus and subvalvar apparatus are heavily involved, so repair is less feasible and mitral valve replacement is often required. Secondary prevention with benzathine penicillin G is part of management.[1]

Ischaemic (functional) MR arises from LV remodelling after myocardial infarction: regional wall motion abnormality (especially infero-basal) displaces the posteromedial papillary muscle, tethering the leaflets (Carpentier IIIb). It may be acute (papillary muscle dysfunction in stunned or infarcted myocardium) or chronic (progressive remodelling).[1]

Functional (non-ischaemic) MR occurs in dilated cardiomyopathy and HFrEF — LV spherical dilation stretches the annulus and tethers the leaflets, and chronic AF with LA enlargement further dilates the annulus. The valve is structurally normal; the MR is a geometric consequence of LV and LA disease.[1]

Mitral annular calcification (MAC) in the elderly (especially women, diabetics, renal failure, Paget disease) is a degenerative calcification of the mitral annulus (a U-shaped ring) that restricts leaflet closure and may invade the conduction system producing heart block. Severe MAC is a surgical challenge — there is no annulus to sew to.[1]

Connective-tissue, systemic and drug causes: Marfan syndrome and Ehlers-Danlos (leaflet prolapse from defective fibrillin or collagen); SLE (Libman-Sacks endocarditis — verrucous vegetations on the atrial surface of the mitral leaflets, often with antiphospholipid antibodies); hypertrophic cardiomyopathy (systolic anterior motion of the mitral leaflet plus MR); prior mediastinal radiotherapy (decades later — fibrotic, calcified, restricted leaflets, Type IIIa); carcinoid (right-sided valves). Drug-induced valvulopathy — fenfluramine-phentermine (fen-phen), dexfenfluramine, ergotamine, pergolide, cabergoline (serotonergic agonists) — produces carcinoid-like lesions: thickened, restricted leaflets with a plaque-like fibrous coating, often regurgitant.[1]

Mitral valve prolapse (MVP) itself is the most common primary precursor in the West: prevalence roughly 2 to 3 percent of the population, female predominance in the young (Barlow myxomatous form), with a characteristic mid-systolic click with or without a late systolic murmur. Most MVP is benign; the minority with severe MR, flail leaflet, or marked myxomatous change are the ones who develop complications.[1]

Epidemiology — cause by geography and setting

MR is the commonest valve lesion of adults in developed countries — mild MR is detectable on echo in roughly 1 to 2 percent of the population, and the prevalence of moderate-to-severe MR rises sharply after age 65, driven by degenerative disease in the elderly and functional MR in the expanding heart-failure population. The age-adjusted prevalence of at-least-moderate MR is approximately 2 percent of adults and approaches 10 percent in those over 75.[1][2]

Cause by geography and setting (high-yield):[1]

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Mortality where it matters: untreated severe symptomatic chronic MR carries a 5-year mortality of roughly 40 percent, and severe secondary MR in HFrEF independently doubles mortality. Acute MR from papillary muscle rupture is near-100 percent fatal without surgery.[1]

Pathophysiology — chronic volume overload versus acute pressure overload

The fundamental lesion is a leak in systole: part of the LV stroke volume takes the low-resistance path back into the LA instead of the high-resistance path into the aorta. The consequences differ completely depending on time-course and on LA compliance.[1][3]

Chronic MR — the volume-overload model

1. Regurgitant volume enters the LA each systole. The total LV stroke volume equals forward stroke volume plus regurgitant volume; the LV therefore ejects a larger total volume at a lower afterload (because blood escapes two ways — the regurgitant orifice acts as a second, low-resistance outflow). By Laplace (wall stress equals pressure times radius over twice wall thickness), the lower systolic pressure and eccentric hypertrophy keep wall stress near-normal despite dilation.
2. The LA and LV dilate to accommodate the extra volume. LV mass increases by eccentric hypertrophy (sarcomeres added in series). EF is preserved or even supranormal because afterload is low — which is why EF overestimates true myocardial contractility in MR and why the threshold for operating (EF under 60 percent) is higher than for other lesions.
3. Compensation can last years: LA compliance rises, LV filling pressure stays near-normal, and the patient is asymptomatic. Forward output is maintained by the increased total stroke volume.
4. Decompensation: as the LV dilates further, contractile fibres overstretch, systolic function falls (often silently), filling pressure rises, LA pressure transmits to the pulmonary veins, and the patient develops exertional dyspnoea, orthopnoea, fatigue. LA enlargement predisposes to atrial fibrillation. Late disease brings pulmonary hypertension (from chronic LA hypertension), tricuspid regurgitation (secondary), and right heart failure.[1]

Acute MR — the pressure-overload emergency

1. A sudden large regurgitant orifice (papillary muscle or chordal rupture) dumps volume into a small, non-compliant LA that has had no time to dilate.
2. LA pressure and pulmonary venous pressure spike in systole (giant v waves on the pulmonary capillary wedge tracing — often exceeding 50 mmHg).
3. The result is acute pulmonary oedema and a fall in forward output, producing cardiogenic shock. The LV cannot compensate because the afterload fall cannot rescue a suddenly enormous regurgitant fraction; EF may even look normal while forward output collapses.[1]

Why ischaemic MR favours the posteromedial papillary muscle

The posteromedial papillary muscle has a single blood supply (the posterior descending artery), whereas the anterolateral papillary muscle has dual supply (LAD plus circumflex). Ischaemia or infarction of the posteromedial muscle (inferior MI) therefore causes dysfunction or rupture far more often — the single most examinable structural fact in MR.[1]

Functional (secondary) MR — geometry, not the valve

In HFrEF or ischaemic cardiomyopathy the LV dilates and becomes spherical; the papillary muscles are displaced apically and laterally, tethering the leaflets so they cannot coapt (Carpentier IIIb). The regurgitant orifice is dynamic — it worsens with ischaemia and with increased LV volume, and shrinks with diuretic or vasodilator therapy and resynchronisation (CRT). This dynamic behaviour explains why treatment of the underlying cardiomyopathy is the first step in secondary MR, and why a fixed surgical annuloplasty without addressing the failing LV often fails.[2]

Clinical presentation — chronic hides, acute shouts

Chronic compensated MR is often asymptomatic for years, detected on a routine murmur or an incidental echo. As decompensation begins:[1]

• Exertional dyspnoea then orthopnoea and paroxysmal nocturnal dyspnoea (pulmonary venous congestion).
• Fatigue from low forward cardiac output.
• Palpitations — atrial ectopics, then atrial fibrillation from LA enlargement.
• Less commonly: right-heart symptoms (ankle swelling, abdominal distension from hepatomegaly, ascites) once pulmonary hypertension and right-heart failure supervene.
• Haemoptysis, hoarseness (Ortner syndrome from the LA compressing the recurrent laryngeal nerve), and embolic events are rarer but described in severe chronic MR.[1]

Acute MR (papillary muscle or chordal rupture) is dramatic:[1]

• Sudden severe dyspnoea, orthopnoea, frothy or pink sputum (acute pulmonary oedema).
• Hypotension, cool peripheries, oliguria, altered sensorium (cardiogenic shock).
• Often in the first 2 to 7 days post-MI (papillary muscle rupture), or after trauma, or spontaneously in severe MVP (chordal rupture).
• The murmur may be surprisingly soft or even absent in acute severe MR because the LA and LV pressures equalise early in systole, abolishing the gradient that generates the murmur — a classic exam trap. Always echo a shocked post-MI patient with new pulmonary oedema.[1]

Mitral valve prolapse presentation: a young, thin woman; atypical chest pain, palpitations, anxiety, autonomic symptoms (postural orthostatic tachycardia, panic-like episodes); the classic auscultatory finding is a mid-systolic click that moves closer to S1 with Valsalva or standing (less preload means earlier prolapse) and later with squatting or handgrip (more preload). A late systolic murmur follows the click if MR is present.[1]

The differential — one systolic murmur, seven answers

A systolic murmur is not always MR. The high-yield differentials with their distinguishing features:[1]

• Aortic stenosis — ejection systolic murmur at the right upper sternal border radiating to the carotids; crescendo-decrescendo; soft or absent A2; ejection click; slow-rising pulse; heaving sustained apex. Handgrip decreases AS (more afterload delays opening) and increases MR; Valsalva decreases AS and MR but increases HOCM.
• HOCM — ejection systolic at the lower left sternal edge; increases with Valsalva and standing (less preload, more obstruction) and decreases with squatting or handgrip; bifid "triple ripple" apex; often a diastolic murmur from concomitant MR.
• Ventricular septal defect (VSD) — pansystolic murmur at the lower left sternal edge with a thrill; radiation is not to the axilla; increases with handgrip; sudden onset post-MI or congenital. Bundle-branch block on ECG.
• Tricuspid regurgitation (TR) — pansystolic at the lower left sternal edge; Carvallo sign (murmur increases with inspiration); prominent cv waves in the JVP and a pulsatile liver; inspiration augments right-sided murmurs, the opposite of left-sided.
• Pulmonary regurgitation (Graham Steell) — early diastolic decrescendo at the lower left sternal edge; pulmonary hypertension features; not a systolic murmur.
• Mitral stenosis — mid-diastolic rumble with presystolic accentuation, opening snap, loud S1; differentiation is by timing, not site.
• Aortic regurgitation — early diastolic decrescendo at the left sternal edge with an Austin Flint mid-diastolic rumble (confused with MS); collapsing water-hammer pulse.[1]

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Bedside assessment — general, pulse, apex, auscultation

General: look for a marfanoid habitus (tall, arm span greater than height, arachnodactyly, high-arched palate, pectus — MVP or Marfan), stigmata of rheumatic fever (mitral facies, history of chorea or Sydenham), endocarditis (splinter haemorrhages, Janeway lesions, Osler nodes, Roth spots, conjunctival petechiae), right-heart failure (raised JVP, hepatomegaly, ankle oedema, ascites), and signs of ischaemia (post-MI scars on ECG, prior revascularisation).[1]

Pulse: AF is common (LA enlargement); the pulse may be small-volume in low-output states or bounding in chronic compensated high-volume MR. Pulsus alternans indicates advanced LV failure.[1]

Apex: displaced, hyperdynamic (thrusting), laterally displaced from LV dilation. An apical systolic thrill suggests severe MR.[1]

Auscultation (reproduce verbatim):[1]

• S1 — soft or absent (incomplete or delayed valve closure; the classic finding). In mild MR, S1 may be normal.
• S2 — usually normal splitting; wide splitting if MR shortens LV ejection (early A2). Loud P2 if pulmonary hypertension has supervened.
• S3 — a third heart sound is common in significant chronic MR (rapid early filling of a volume-loaded LV) and does NOT imply heart failure in this context, as it would in AS.
• Murmur — pansystolic (holosystolic), high-pitched, blowing, loudest at the apex, radiating to the axilla (posterolateral jet) or to the left sternal edge or base (anterior or anterior-leaflet jet). Intensity does not reliably correlate with severity — a soft murmur in acute MR is the classic trap.
• MVP — mid-systolic (non-ejection) click with or without a late systolic murmur. The click moves toward S1 with Valsalva or standing, away from S1 (later) with squatting or handgrip.[1]

Bedside manoeuvres (memorise the table):[1]

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Investigations — confirm, grade, and exclude CAD before surgery

The goal of investigation is to confirm the diagnosis, define the mechanism (Carpentier type), grade severity, assess the LV (size and function) and the pulmonary circulation, and exclude concomitant CAD before surgery.[4]

Electrocardiogram (ECG): non-specific but supportive. LA enlargement (a bifid P-wave in lead II — "mitral P", P-wave duration over 120 ms, terminal P-negative force in V1 greater than 40 ms squared); atrial fibrillation; LV hypertrophy (voltage criteria) and strain; Q waves (prior infarction) suggesting ischaemic MR; right-axis deviation or RBBB if pulmonary hypertension has developed.[1]

Chest X-ray: cardiomegaly with LA enlargement (a double shadow along the right heart border, splaying of the carina, left main bronchus elevation, straightening of the left heart border); in chronic MR, signs of pulmonary venous congestion (upper-lobe blood diversion, Kerley B lines, interstitial oedema); in acute MR, florid pulmonary oedema with a near-normal heart size (no time to dilate).[1]

Transthoracic echocardiography (TTE) — the cornerstone. TTE defines mechanism, severity, LV and LA size, pulmonary artery pressure, and excludes other valve disease.[4]

• Mechanism — leaflet morphology (myxomatous or prolapse, rheumatic thickening, vegetation, flail, restricted tethering), annular size, regional wall motion.
• Severity — integrated using colour Doppler jet area, vena contracta width, the proximal isovelocity surface area (PISA)-derived effective regurgitant orifice area (EROA) and regurgitant volume or fraction, and the pulmonary venous flow pattern (systolic blunting or reversal in severe MR).[1]

Severity grading of primary MR (ASE or EACVI, reproduced verbatim):[4]

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For secondary MR the severe thresholds are lower (EROA at least 0.30 cm2, regurgitant volume at least 45 mL) because the regurgitant orifice is dynamic and the LV is already failing.[2]

Transoesophageal echocardiography (TOE or TEE): reserved for inconclusive TTE, detailed preoperative anatomy (which scallop is flail — usually P2; feasibility of repair), intraoperative guidance, and to assess for LAA thrombus before cardioversion. 3D TOE is now standard in surgical planning and dramatically improves the surgeon's spatial map of the prolapsing segment.[1]

Other imaging:[1]

• Cardiac MRI — the gold standard for LV volumes, EF and mass, useful when echo windows are poor and for myocardial viability (late gadolinium enhancement to distinguish ischaemic from non-ischaemic functional MR, and to quantify MR volume directly by phase-contrast).
• Coronary angiography — before surgery in men over 40, postmenopausal women, and anyone with risk factors or ischaemic ECG, to exclude concomitant CAD needing CABG at the same operation.
• Exercise echocardiography — in symptomatic patients whose resting echo severity looks disproportionate, or to document a rise in pulmonary artery systolic pressure (PASP over 60 mmHg on exercise supports intervention).[9]

BNP or NT-proBNP — a rising level in asymptomatic severe MR is an adverse prognostic marker and a Class IIa trigger for closer surveillance or early surgery consideration.[1]

Acute MR — the resuscitation bundle

Acute severe MR is a cardiovascular emergency. The priorities are oxygenation, afterload reduction, inotropic support and mechanical support while arranging definitive (surgical) repair.[1][2]

• Airway and breathing — high-flow oxygen; non-invasive ventilation (CPAP or BiPAP) for pulmonary oedema (reduces the work of breathing, improves oxygenation, drops preload and afterload); intubate if failing.
• Vasodilator therapy (the single most useful pharmacological lever) — IV sodium nitroprusside 0.3 to 3 micrograms/kg/min (titrated), or IV glyceryl trinitrate 10 to 200 micrograms/min, to reduce afterload and preferentially drive blood forward into the aorta. Avoid if hypotensive.
• Inotropes — dobutamine 2.5 to 20 micrograms/kg/min or milrinone 0.125 to 0.75 micrograms/kg/min for low-output or cardiogenic shock; milrinone also reduces afterload (an inodilator).
• Mechanical circulatory support — an intra-aortic balloon pump (IABP) reduces afterload and augments coronary perfusion, dramatically improving forward output in acute MR; consider VA-ECMO in refractory shock as a bridge to surgery.
• Diuretics — IV furosemide 20 to 80 mg bolus (or infusion) for pulmonary congestion.
• Avoid pure vasoconstrictors where possible (they worsen the regurgitant fraction by raising afterload); if vasopressors are unavoidable, noradrenaline is preferred to pure alpha-agonists.
• Emergency surgery — once stabilised, the definitive treatment is urgent mitral valve repair or replacement. In ischaemic acute MR (papillary muscle rupture) the operative mortality is high (25 to 40 percent) but surgery is the only chance of survival.[1]

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Definitive management — primary and secondary MR diverge

Management is fundamentally different for primary versus secondary MR and is driven by symptoms, LV size and function, and repairability.[1][2]

Primary (organic) MR — the surgical triggers

[1] [8]

Symptomatic severe primary MR with LVEF over 30 percent — surgery is Class I (repair preferred).[1]

Why the EF threshold is 60 percent, not 50 percent. EF overestimates contractility in MR because afterload is low; an EF of 55 percent in severe MR is already abnormal. Waiting for EF to fall to 50 percent means the ventricle is already irreversibly damaged — the central pitfall in MR timing.[1]

Repair versus replacement — the cornerstone decision

Mitral valve repair is strongly preferred (Class I) for posterior leaflet (especially P2) prolapse or flail, where durable repair rates at expert centres exceed 95 percent. Repair preserves the native subvalvar apparatus (better LV function), avoids lifelong anticoagulation (mechanical valves) and reoperation (bioprosthetic valves), and carries lower operative and long-term mortality than replacement. Replacement is reserved for extensive bileaflet disease, severe calcification, rheumatic destruction, destructive endocarditis, or when repair is not feasible at the operating centre. When replacement is necessary, chordal-sparing techniques preserve LV function and reduce postoperative LV dysfunction.[1]

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Surgical techniques examiners reward you for naming:[1]

• Annuloplasty ring — a prosthetic ring (complete or partial band) sewn around the mitral annulus to reduce its size and restore coaptation. Used alone in functional MR (a restrictive or undersized annuloplasty) and added to nearly every degenerative repair to stabilise the annulus. Undersized annuloplasty is the classic operation for functional or ischaemic MR (often combined with CABG).
• Triangular or quadrangular resection — the standard operation for posterior (P2) prolapse: resect the prolapsing segment, reconstruct the leaflet, reinforce with an annuloplasty ring. The most durable repair in all of valve surgery.
• Chordal replacement (neochordae) — synthetic polytetrafluoroethylene (ePTFE, Gore-Tex) chords anchored to the papillary muscle and the prolapsing leaflet edge, used especially for anterior leaflet and bileaflet prolapse.
• Edge-to-edge (Alfieri) stitch — approximates the free edges of the anterior and posterior leaflets at the regurgitant jet, creating a double-orifice valve. The surgical basis of the transcatheter MitraClip.
• Chordal-sparing MVR — preserving the native leaflets and subvalvar apparatus during replacement prevents catastrophic postoperative LV dysfunction.[1]

Anticoagulation after mechanical MVR: lifelong warfarin with INR target 3.0 (range 2.5 to 3.5) for a mechanical mitral valve — higher than the aortic target, because the mitral position is more thrombogenic (lower flow velocity); add aspirin 75 to 100 mg if there are additional risk factors. Bioprosthetic valves: warfarin INR 2.5 for 3 months then aspirin alone (unless another indication). Mechanical valves last 20 to 30 years; bioprosthetic valves deteriorate structurally over 10 to 15 years (faster in younger patients and renal failure).[1]

Secondary (functional) MR — treat the cardiomyopathy first

Treat the underlying cardiomyopathy first — guideline-directed medical therapy (GDMT) for HFrEF: beta-blocker plus ACE-inhibitor or ARNI plus MRA plus SGLT2 inhibitor at target doses, diuretics for congestion, digoxin or anticoagulation for AF, and cardiac resynchronisation therapy (CRT) if QRS over 150 ms with LBBB (CRT reduces functional MR by improving LV synchrony and reducing annular size).[2]

Surgery or TEER for secondary MR is adjunctive, reserved for symptoms refractory to optimal GDMT with persistent severe MR. Both surgical restrictive annuloplasty (often at the time of CABG in ischaemic MR) and transcatheter edge-to-edge repair (TEER, MitraClip) are options; TEER is preferred in high surgical-risk patients. The 2021 ESC guideline elevates TEER to a Class IIa recommendation in symptomatic patients with severe secondary MR despite optimal GDMT who are unsuitable for surgery.[2]

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Anticoagulation for atrial fibrillation in MR (the commonest complication) — use CHA2DS2-VASc (score at least 2 in men or at least 3 in women means oral anticoagulation; the mitral valve disease itself no longer mandates anticoagulation unless it is rheumatic MS, which remains a high-risk condition). DOACs are acceptable in non-valvular AF (which includes non-rheumatic MR); for rheumatic MR with AF, warfarin is conventional.[1]

Special situations you will actually meet

• Mitral valve prolapse (MVP) — young women; mid-systolic click with or without a late systolic murmur; the click moves toward S1 with Valsalva. Most are benign; beta-blockers for symptomatic palpitations or chest pain; surveillance echo for progressive MR; surgery for severe MR. High-risk features: flail leaflet, severe MR, marked LA enlargement, EF fall — these define the minority needing intervention. Risk-stratify with echo: thickened (over 5 mm) redundant leaflets plus severe MR carry higher risk of sudden death and endocarditis.[1]
• Ischaemic MR — papillary muscle dysfunction (Type IIIb, chronic) or rupture (acute, days 2 to 7 post-MI). The posteromedial papillary muscle (single PDA supply) ruptures more often than the anterolateral (dual LAD plus LCx supply). Acute rupture is a surgical emergency with high mortality. Chronic ischaemic MR — revascularise (CABG) with or without restrictive annuloplasty; outcome depends on LV viability and reversibility.[1]
• Functional MR (non-ischaemic) — DCM or HFrEF; treat the cardiomyopathy, consider CRT, TEER if refractory. Dynamic — severity changes with volume status and ischaemia, so exercise or stress echo can unmask severity.[9]
• Rheumatic MR — commonest cause in the developing world; often mixed MS and MR; thickened leaflets, restricted motion (Type IIIa), calcified annulus; repair less feasible, so often MVR. Antistreptococcal prophylaxis with benzathine penicillin G 1.2 million units IM every 3 to 4 weeks (or for at least 10 years after the last attack, or until age 40).[1]
• Infective endocarditis — acute or subacute MR from a vegetation preventing coaptation, leaflet perforation, or chordal rupture; manage per endocarditis guidelines (cultures, targeted antibiotics for 4 to 6 weeks, surgery for heart failure, uncontrolled infection, a large vegetation over 10 mm, embolism).[1]
• Mitral annular calcification (MAC) — elderly women, diabetics, CKD; a U-shaped calcific ring; restricts leaflet closure; may invade the conduction system (heart block). A surgical challenge (no annulus to sew to); transcatheter options are emerging.[1]
• Acute severe MR (papillary muscle or chordal rupture) — emergency as above; afterload reduction (nitroprusside, IABP) plus emergency surgery.[1]
• Drug-induced valvulopathy (fenfluramine, cabergoline, pergolide) — withdraw the offending drug; leaflet changes may stabilise or regress; surgery if severe MR persists.[1]
• Hypertrophic cardiomyopathy — systolic anterior motion (SAM) of the mitral leaflet produces LVOT obstruction plus MR; treat with beta-blockers or disopyramide, avoid vasodilators and inotropes; septal reduction therapy (myectomy or alcohol ablation) if refractory.[1]

How patients with MR come to harm (the preventable list)

• Missing acute MR in the post-MI patient with pulmonary oedema and a soft murmur — the LA and LV pressures have equalised; only the echo will save them, and only the surgeon will fix them.[1]
• Operating too late in chronic primary MR — waiting for symptoms; by then LV dysfunction is irreversible. The EF-under-60-percent and LVESD-at-least-40-mm triggers exist precisely to prevent this.[1]
• Trusting the EF — EF overestimates contractility in MR because afterload is low; an EF of 55 percent in severe MR is already abnormal.[1]
• Treating secondary MR like primary — surgery on functional MR without optimising GDMT fails; treat the cardiomyopathy first.[2]
• Over-relying on colour jet area — it is load-dependent and eccentric jets understate severity; integrate EROA, vena contracta and pulmonary venous flow.[4]
• Forgetting anticoagulation in AF — AF in MR carries stroke risk; assess CHA2DS2-VASc.[1]
• Prescribing a DOAC in rheumatic MR with AF — only non-rheumatic MR qualifies for a DOAC; rheumatic mitral disease still means warfarin.[1]

Prognosis and disposition

• Mitral valve repair — operative mortality under 1 percent in expert centres for degenerative MR; 10-year survival over 90 percent, freedom from reoperation over 95 percent. Repair is the single biggest determinant of long-term outcome.[1]
• Mitral valve replacement — operative mortality 2 to 6 percent depending on comorbidity; mechanical valves durable (20 to 30 years) but require lifelong warfarin; bioprosthetic valves avoid warfarin but have structural deterioration (10 to 15-year reoperation rates).[1]
• Untreated severe chronic MR — progressive LV dilation and dysfunction; 5-year mortality of roughly 40 percent once symptomatic; once EF falls below 50 percent the outlook worsens markedly.[1]
• Acute MR (papillary muscle rupture) — mortality 25 to 40 percent with surgery, near-100 percent without; early diagnosis and IABP bridge to surgery are decisive.[1]
• Functional or secondary MR — prognosis tracks the underlying cardiomyopathy; MR severity is an independent adverse marker in HFrEF (COAPT showed a survival benefit of TEER in selected patients).[5]
• Asymptomatic severe primary MR — surveillance echo annually (or 6-monthly if borderline LV size or progressive MR); prompt reporting of new symptoms; refer to a heart valve centre when triggers are met. Endocarditis prophylaxis only if prosthetic valve, prior IE, or specific congenital disease.[1]

Pregnancy and special populations

• Pregnancy — mild-to-moderate chronic MR is usually well tolerated (systemic vascular resistance falls in pregnancy, reducing regurgitant volume). Severe MR may decompensate from the gestational volume load (especially third trimester and labour); manage with beta-blockers (rate control), diuretics (avoid over-diuresis), serial echo, and avoid the supine position (aortocaval compression). Vaginal delivery with early epidural (avoid sudden BP swings) is preferred; caesarean for obstetric indications. ACE-inhibitors and ARBs are CONTRAINDICATED in pregnancy (switch to labetalol, nifedipine or methyldopa). Anticoagulation for AF: LMWH in pregnancy, warfarin avoided in the first trimester. Repair before pregnancy if severe primary MR is planned.[1]
• Elderly — annular calcification is common, functional MR from HFrEF or HFpEF, comorbidity raises surgical risk; TEER is preferred for inoperable severe MR. Watch for coexistent AS and AF.[1]
• Children — congenital causes (cleft mitral leaflet, atrioventricular septal defect, parachute mitral valve); repair preferred to preserve valve growth; weight-based drug dosing.[1]
• Rheumatic or Indigenous populations — younger patients with mixed MS and MR, recurrent acute rheumatic fever; secondary prophylaxis with benzathine penicillin G is part of management; high recurrence rates.[1]
• End-stage renal disease — heavy annular calcification, accelerated bioprosthetic deterioration, high surgical risk; TEER or medical management often preferred.[1]

Evidence and the names that score marks

Landmark trials examiners name:[1]

• COAPT (2018, NEJM) — in secondary MR with HFrEF, TEER (MitraClip) on top of maximal GDMT reduced heart-failure hospitalisations and all-cause mortality at 2 years in patients with disproportionate MR (MR severity greater than expected for LV size). A positive trial that redefined secondary MR management.[5]
• MITRA-FR (2018, NEJM) — in proportionate secondary MR (larger failing LVs, milder MR), TEER added to GDMT did not reduce death or HF hospitalisation. A negative trial that taught us to select COAPT-type patients.[6]
• EVEREST II (2011, NEJM) — randomised TEER versus surgery in predominantly primary MR; TEER was safer but less effective (more residual MR and reoperation). Established surgery as the gold standard for primary MR and TEER for inoperable or high-risk patients.[7]
• Kang 2009 (Circulation) — early mitral repair in asymptomatic severe degenerative MR reduced the composite of operative mortality, hospitalisation for HF, and progression to symptomatic MR — supporting an early-surgery strategy at expert centres.[8]

Guideline differences:[1][2]

• AHA/ACC 2020 — surgery triggers as above; mitral valve repair is preferred; early surgery at a Primary or Comprehensive Valve Center with a mitral repair rate over 95 percent for degenerative posterior disease.
• ESC/EACTS 2021 — broadly aligned; sets a Class IIa for early surgery in asymptomatic severe primary MR with preserved LV function and a high likelihood of durable repair; elevates TEER to Class IIa in symptomatic severe secondary MR refractory to GDMT.
• Both guidelines agree: the EF threshold for surgery is under 60 percent (not 50 percent) because EF overestimates contractility in MR; repair is preferred over replacement; TEER is not a substitute for surgery in operable primary MR.[1]

Controversies: the role of TEER in primary MR in high-risk surgical patients; the optimal management of ischaemic MR at the time of CABG (the CTSN trials showed mild-to-moderate ischaemic MR does not benefit from additive annuloplasty at CABG in the short term); whether to intervene on asymptomatic moderate secondary MR at the time of other cardiac surgery; transcatheter mitral valve replacement (TMVR) versus TEER.[1]

The mantra, and the viva honesty line

[1]

The mantra: pansystolic at the apex to the axilla, soft S1, an S3 — and operate at EF 60, not 50, before the ventricle fails.[1][2]

Ward-round test — three stems, thirty seconds each

Stem 1 — the 3am post-MI patient from the top of the topic (answer)

A 62-year-old man, four days after an inferior STEMI, wakes with acute pulmonary oedema and a soft, short murmur at the apex. BP 96/60, saturations 84 percent on room air. What is the diagnosis, the structural reason for that muscle, and the immediate management? Model: Acute severe MR from posteromedial papillary muscle rupture. The posteromedial papillary muscle has a single blood supply (PDA), so it is preferentially infarcted in inferior MI. The murmur is soft because the LA and LV pressures have equalised. Immediate management: oxygen and NIV, IV sodium nitroprusside for afterload reduction, IV furosemide, an IABP as a bridge, and emergency surgical repair or replacement (operative mortality 25 to 40 percent, but near-100 percent without surgery). Reach for the echo before the furosemide.[1]

Stem 2 — the asymptomatic woman with a prolapsing valve (answer)

A 50-year-old woman with known mitral valve prolapse is referred because her echo now shows severe primary MR (EROA 0.44 cm2) with EF 58 percent and LVESD 43 mm. She walks five kilometres a day and denies symptoms. What do you do, and why is the EF threshold different from other valve diseases? Model: She meets a Class I surgical trigger — asymptomatic severe primary MR with EF under 60 percent or LVESD at least 40 mm. Refer to a heart valve centre for mitral valve repair (posterior leaflet prolapse has a 95 percent repair rate). The EF threshold is 60 percent, not 50 percent, because in MR the low afterload inflates the EF — by the time it falls below 60 percent true contractility is already impaired, and waiting risks irreversible LV dysfunction. Do not "watch and wait" once the triggers are crossed.[1][8]

Stem 3 — the heart-failure patient referred for a MitraClip (answer)

A 72-year-old with HFrEF (EF 28 percent, LV end-diastolic volume 240 mL) on maximal GDMT has severe secondary MR (EROA 0.42 cm2, RV 55 mL) and keeps being admitted with pulmonary oedema. Is a MitraClip appropriate, and which trial decides it? Model: Yes — she is a COAPT-type patient: disproportionate secondary MR (severe MR for a relatively small LV). TEER with MitraClip on top of maximal GDMT reduced HF hospitalisation by 47 percent and all-cause mortality at 2 years in COAPT (Stone 2018). She is exactly the phenotype that benefits. MITRA-FR (proportionate MR, larger LV, milder MR) was negative — she is not that patient. Confirm suitability with TOE anatomy (coaptation depth, leaflet length, flail gap) before proceeding.[5][6]

References

1. [1]Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: A report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines J Thorac Cardiovasc Surg, 2021.PMID 33972115
2. [2]Vahanian A, Beyersdorf F, Praz F, et al. 2021 ESC/EACTS Guidelines for the management of valvular heart disease Eur Heart J, 2022.PMID 34453165
3. [3]Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines Circulation, 2014.PMID 24589853
4. [4]Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance J Am Soc Echocardiogr, 2017.PMID 28314623
5. [5]Stone GW, Lindenfeld J, Abraham WT, et al. Transcatheter Mitral-Valve Repair in Patients with Heart Failure N Engl J Med, 2018.PMID 30280640
6. [6]Obadia JF, Messika-Zeitoun D, Leurent G, et al. Percutaneous Repair or Medical Treatment for Secondary Mitral Regurgitation N Engl J Med, 2018.PMID 30145927
7. [7]Feldman T, Foster E, Glower DD, et al. Percutaneous repair or surgery for mitral regurgitation N Engl J Med, 2011.PMID 21463154
8. [8]Kang DH, Kim JH, Rim JH, et al. Comparison of early surgery versus conventional treatment in asymptomatic severe mitral regurgitation Circulation, 2009.PMID 19188506
9. [9]Lancellotti P, Dulgheru R, Go YY, et al. Stress echocardiography in patients with native valvular heart disease Heart, 2018.PMID 29217633