Mitral Valve Prolapse

Detailed Overview

MVP is the most common cause of primary mitral regurgitation in developed countries. While the vast majority of individuals with MVP are asymptomatic and have a benign course, a subset may develop severe mitral regurgitation, infective endocarditis, or sudden cardiac death (malignant MVP syndrome). The condition is frequently identified incidentally during physical examination by the characteristic mid-systolic click and late systolic murmur. Diagnosis and risk stratification heavily rely on echocardiography.

Epidemiology & Demographics

MVP affects approximately 2% to 3% of the general population. It is slightly more prevalent in females, especially in younger age groups, but severe MVP requiring surgery is more common in males > 50 years of age.

Etiological Mechanism

The majority of cases are primary (idiopathic) with familial clustering (autosomal dominant inheritance with variable penetrance, linked to loci on chromosomes 11, 15, and 16). Secondary MVP is associated with connective tissue disorders such as Marfan syndrome (FBN1 mutation) and Ehlers-Danlos syndrome, as well as polycystic kidney disease.

Primary Causes

Idiopathic myxomatous degeneration

Marfan syndrome

Ehlers-Danlos syndrome

Osteogenesis imperfecta

• Family History: A first-degree relative with MVP increases the risk significantly.
• Connective Tissue Disease: Conditions like Marfan syndrome predispose individuals to early and severe MVP.

Histologically, MVP is characterized by the proliferation of the spongiosa layer of the valve with accumulation of proteoglycans (myxomatous degeneration), displacing the fibrosa layer. This leads to weakened, redundant valve leaflets and chordae tendineae. During systole, the increased left ventricular pressure forces the weakened leaflets to balloon backwards (prolapse) past the mitral annulus into the left atrium. This abnormal motion can put stress on the papillary muscles and left ventricular myocardium, contributing to arrhythmogenesis.

Characteristic Clinical Presentation

• Asymptomatic: Most patients have no symptoms and are diagnosed incidentally.
• Atypical chest pain: Sharp, localized chest pain unrelated to exertion.
• Palpitations: Sensation of rapid or irregular heartbeats, often due to premature ventricular contractions (PVCs).
• Dyspnea or fatigue: May develop if significant mitral regurgitation ensues.

Physical Examination Signs

• Mid-systolic click, heard best at the apex.
• Late systolic murmur if accompanied by mitral regurgitation; the murmur lengthens with standing/Valsalva and shortens with squatting.

• Severe Mitral Regurgitation: Due to progressive leaflet stretching or sudden chordal rupture.
• Infective Endocarditis: Abnormal blood flow and endothelial damage predispose to bacterial seeding.
• Arrhythmias: Including PVCs, supraventricular tachycardias, and rarely ventricular tachycardia/fibrillation leading to sudden cardiac death.

Diagnostic Criteria & Guidelines

Echocardiographic demonstration of systolic displacement (prolapse) of one or both mitral valve leaflets by ≥ 2 mm into the left atrium beyond the plane of the mitral annulus in the parasternal long-axis view.

Differential Diagnosis

• Hypertrophic Cardiomyopathy
• Rheumatic Mitral Valve Disease
• Tricuspid Valve Prolapse
• Atrial Septal Defect

Laboratory Tests & Biomarkers

• Genetic Testing: Considered if syndromic features (e.g., Marfan) are present (e.g., FBN1 testing).

Imaging Modalities & Findings

• Echocardiogram:
• Holter Monitor:

• Classic MVP
  Leaflet thickness > 5 mm, indicating significant myxomatous degeneration.
• Non-classic MVP
  Leaflet thickness < 5 mm.

Second-Line & Adjunctive Therapy

If beta-blockers are not tolerated or ineffective, non-dihydropyridine calcium channel blockers (e.g., Diltiazem) can be used. For high PVC burden or malignant arrhythmias, antiarrhythmics or ablation may be considered.

Surgical & Procedural Management

Surgical Mitral Valve Repair is the definitive treatment if the patient develops severe symptomatic mitral regurgitation, or asymptomatic severe MR with LVEF ≤ 60% or LVESD ≥ 40 mm. Repair is preferred over replacement.

Recommended Lifestyle Changes

• Avoid stimulants such as excessive caffeine and pseudoephedrine, which can exacerbate palpitations.
• Maintain adequate hydration.
• Aerobic exercise is generally encouraged, but competitive sports may be restricted if severe MR or history of malignant arrhythmias exists.

Patient Counseling & Advice

Reassure the patient that MVP is usually a benign condition that does not affect life expectancy. Explain the symptoms of progression (shortness of breath, extreme fatigue) and the importance of regular follow-up. Endocarditis prophylaxis is NO LONGER recommended for MVP alone.

Follow-Up & Monitoring Schedule

Asymptomatic patients with MVP and no/mild MR: clinical exam every 3-5 years. If moderate to severe MR: echocardiogram every 6-12 months.

Preventive Strategies

MVP cannot be prevented as it is primarily genetic. Complications can be minimized by avoiding severe hypertension and treating infections promptly.

Generally excellent. The mortality rate is similar to the general population. Less than 10% of patients require surgical intervention over their lifetime.