Key Facts

Mitral valve prolapse (MVP) is the billowing of one or both mitral valve leaflets into the left atrium during systole by ≥2 mm beyond the mitral annular plane. It is the most common valvular abnormality and is usually benign.

Epidemiology

• Prevalence: ~2-3% of the general population
• More commonly diagnosed in women, but men more likely to develop significant MR
• Peak diagnosis in young adulthood (20-40 years)
• Most common cause of isolated mitral regurgitation requiring surgery in developed countries

Aetiology

• Primary (myxomatous): most common; redundant leaflet tissue with myxomatous degeneration
  • Often idiopathic or familial (autosomal dominant with variable penetrance)
  • FLNA gene mutations in some X-linked familial cases
• Secondary: associated with connective tissue disorders
  • Marfan syndrome, Ehlers-Danlos syndrome, osteogenesis imperfecta
  • Polycystic kidney disease, Graves disease
  • Turner syndrome, William syndrome

Pathophysiology

• Myxomatous degeneration: accumulation of glycosaminoglycans in the spongiosa layer → leaflet thickening and redundancy
• Redundant leaflet billows into LA during systole
• Chordae may elongate or rupture → flail leaflet → acute severe MR
• In most patients: trivial or mild MR, clinically insignificant
• Progressive myxomatous change over decades may lead to significant MR requiring intervention

Typical Presentation

• Most patients are asymptomatic — discovered incidentally on auscultation or echocardiography
• Atypical chest pain (non-exertional, sharp, left-sided)
• Palpitations (usually benign PVCs or SVTs)
• Anxiety, fatigue (associated, not causative)
• Dyspnoea if significant MR develops

Auscultatory Findings

• Mid-systolic click (tensing of redundant leaflet/chordae)
• ± Late systolic murmur (MR following the click)
• Dynamic auscultation (exam favourite):
  • Standing/Valsalva: click and murmur move earlier in systole (reduced preload → earlier prolapse)
  • Squatting: click and murmur move later (increased preload → delayed prolapse)

Complications

• Progressive mitral regurgitation (most important)
• Chordal rupture → acute severe MR
• Infective endocarditis (risk proportional to degree of MR)
• Arrhythmias: PVCs, SVTs, rarely ventricular arrhythmias
• Cerebrovascular events (rare): platelet-fibrin deposits on valve
• Sudden cardiac death (very rare, associated with arrhythmic MVP)

Red Flags

• Symptoms of significant MR (dyspnoea, exercise intolerance)
• Acute chest pain with sudden dyspnoea (chordal rupture → acute MR)
• Syncope (arrhythmic MVP — rare)
• Marfanoid habitus (screen for Marfan syndrome)

Bedside

• Auscultation: mid-systolic click ± late systolic murmur with dynamic manoeuvres
• ECG: usually normal; may show T-wave inversions in inferior leads, PVCs

Bloods

• Routine bloods generally normal
• BNP/NT-proBNP: if heart failure suspected

Imaging

• Transthoracic echocardiography: diagnostic gold standard
  • Leaflet displacement ≥2 mm beyond annular plane in parasternal long-axis view
  • Leaflet thickness ≥5 mm (myxomatous/Barlow disease)
  • Assess degree of MR, LV function and dimensions
• TOE: detailed valve anatomy pre-surgical repair
• Cardiac MRI: if echo equivocal; late gadolinium enhancement in papillary muscles may identify arrhythmic MVP

Special Tests

• Holter monitor: if palpitations; assess for ventricular ectopy
• Exercise testing: if symptoms disproportionate to echo findings
• Genetic testing: if Marfan or other connective tissue disorder suspected

Non-pharmacological

• Reassurance for asymptomatic patients with trivial/mild MR
• No exercise restriction for mild MVP without significant MR
• Avoid excessive caffeine, stimulants if palpitations bothersome
• Serial echocardiographic monitoring: annually if moderate MR; 3-5 yearly if mild

Pharmacological

• Beta-blockers (e.g., propranolol 10-40mg TDS): for symptomatic palpitations/chest pain
• Standard heart failure medications if significant MR develops (ACEi, beta-blocker, diuretics)
• Antibiotic prophylaxis: not routinely recommended by NICE for dental procedures (only if prior endocarditis)
• Antiplatelet therapy for unexplained TIA/stroke (aspirin 75mg or clopidogrel 75mg)

Surgical/Interventional

• Mitral valve repair: preferred for severe MR from MVP (repair rates >90% in experienced centres)
• Indications: same as for primary MR (symptomatic severe MR; asymptomatic with LVEF ≤60% or LVESD ≥40 mm; flail leaflet; new AF; pulmonary hypertension)
• Emergency surgery: for acute chordal rupture with severe MR and haemodynamic compromise

Referral Criteria

• Moderate or greater MR: cardiology follow-up for serial monitoring
• Severe MR: surgical assessment
• Symptoms disproportionate to echo findings: further investigation
• Marfanoid features: genetics referral

• Excellent prognosis for the majority: same life expectancy as general population
• ~5-10% develop significant MR requiring intervention over 10-20 years
• Risk of progression: older age, male sex, thickened leaflets (>5 mm), flail leaflet
• Risk of endocarditis: ~1-2% lifetime if no significant MR; higher with MR
• Sudden cardiac death: extremely rare (<1 in 10,000 per year); associated with bileaflet prolapse, complex ventricular ectopy, fibrotic papillary muscles
• Post-mitral valve repair for MVP: excellent long-term outcomes with >90% freedom from reoperation at 10 years

Dynamic Auscultation in MVP

Features of Arrhythmic MVP (High-Risk Subset)