What is the significance and management of mitral valve prolapse?

Significance and Management of Mitral Valve Prolapse

Mitral valve prolapse (MVP) is predominantly a benign condition affecting 1-2.5% of the population, but requires risk stratification based on specific high-risk features including leaflet thickness ≥5mm, significant mitral regurgitation (MR), male gender over 45 years, and bileaflet involvement, as these patients face substantially higher risks of complications including progressive MR requiring surgery, endocarditis, arrhythmias, and sudden cardiac death. 1, 2

Clinical Significance and Risk Stratification

Prevalence and Natural History

• MVP prevalence is 1-2.5% using current strict echocardiographic criteria (≥2mm systolic billowing above the mitral annulus in parasternal long-axis view), far lower than previously reported due to refined diagnostic standards 1
• The condition is most commonly diagnosed in the third and fourth decades of life, with higher incidence in women for diagnosis but paradoxically worse outcomes in men 3, 4
• Most patients remain asymptomatic for an average of 25 years after initial murmur detection, but once symptoms develop, rapid deterioration often occurs within one year 5

High-Risk Features Requiring Intensive Monitoring

The following echocardiographic and clinical features identify patients at substantially elevated risk:

• Leaflet thickness ≥5mm is the single most important predictor of complications, associated with increased rates of endocarditis (3.5% vs 0%), severe MR (11.9% vs 0%), and need for valve replacement (6.6% vs 0.7%) 1
• Bileaflet prolapse, particularly in women with T-wave abnormalities and complex ventricular ectopy, defines a high-risk syndrome for sudden cardiac death 1
• Male gender over age 45 years concentrates risk disproportionately, with approximately 5% of affected men ultimately requiring valve surgery versus 1.5% of women 4
• Redundant leaflets with myxomatous degeneration carry higher risk than simple fibroelastic deficiency 1

Major Complications and Their Management

Progressive Mitral Regurgitation

• Severe MR develops in approximately 15% of MVP patients, often precipitated by chordal rupture (occurring in 51% of surgical cases) or atrial fibrillation (56% of surgical cases) 5, 6
• Surgery is mandatory for symptomatic patients with severe primary MR and LVEF >30% 2
• Asymptomatic patients require surgery when severe MR is accompanied by any of: LVEF <60%, LV end-systolic dimension ≥40mm, new-onset atrial fibrillation, or pulmonary hypertension 2
• Mitral valve repair is strongly preferred over replacement when technically feasible, with superior outcomes at experienced centers 1, 2

Sudden Cardiac Death Risk

• SCD occurs in 1.4-2.4% of MVP patients, with the highest risk in middle-aged women (around age 40) with prior syncope or documented ventricular arrhythmias 6, 1
• Among 163 sudden cardiovascular deaths in young people, MVP was the sole cardiac pathology in 10% 1
• LV fibrosis in papillary muscles has been identified in MVP patients with ventricular arrhythmias or SCD 1
• Infero-lateral ST segment changes and QT prolongation may serve as markers of arrhythmic risk 1

Infective Endocarditis

• MVP is the leading predisposing cardiovascular diagnosis in most endocarditis series 1
• Endocarditis occurs in 2.9% of MVP patients overall 6
• Antibiotic prophylaxis is indicated only for patients with audible pan-systolic or end-systolic murmurs indicating MR 6

Thromboembolic Events

• MVP is found in 20-30% of patients with neurological events before age 45 6
• Fibrin emboli are responsible for visual symptoms involving ophthalmic or posterior cerebral circulation 1

Management Algorithm

Surveillance Strategy Based on MR Severity

Mild MR (asymptomatic):

• Clinical follow-up every 12 months 2
• Echocardiography every 2 years 2

Moderate MR (asymptomatic):

• Clinical follow-up every 6 months 2
• Annual echocardiography 2

Severe MR (asymptomatic):

• Clinical evaluation every 6 months 2
• Annual echocardiography 2
• Immediate surgical referral if any of the following develop: symptoms, LVEF <60%, LVESD ≥40mm, new atrial fibrillation, or pulmonary hypertension 2

Medical Management

Heart Failure Symptoms:

• ACE inhibitors should be used in patients with advanced MR and severe symptoms who are not surgical candidates 2
• There is no evidence supporting vasodilators including ACE inhibitors in chronic MR without heart failure 2
• Beta-blockers and spironolactone for standard heart failure management 2

Arrhythmia Management:

• Beta-blockers are first-line therapy for frequent ventricular ectopy (>30/hour), bigeminy, polymorphism, or documented ventricular tachycardia 6
• ICD implantation should be considered for patients presenting with sustained ventricular tachyarrhythmias 1

Anticoagulation:

• Target INR 2-3 for permanent or paroxysmal atrial fibrillation, history of systemic embolism, or left atrial thrombus 2
• Anti-platelet agents for primary prevention in high-risk patients; anticoagulation for recurrent thromboembolic events 6

Surgical Considerations

Optimal Candidates for Repair:

• Single segment posterior leaflet flail due to fibroelastic deficiency without calcification has the highest success rate and should never undergo replacement without attempted repair 1
• Focal posterior prolapse or flail can be managed by most experienced surgeons 1

Complex Cases Requiring Specialized Centers:

• Anterior leaflet prolapse, bileaflet involvement, or Barlow's disease require referral to high-volume centers with experienced mitral surgeons 1
• Nonresection techniques using PTFE neochord reconstruction or chordal transfer are preferred for anterior leaflet and bileaflet prolapse 1

Critical Pitfalls to Avoid

• Do not delay surgery until symptoms develop or LV dysfunction occurs, as earlier intervention leads to improved survival and functional outcomes 2
• Symptom onset is itself a negative prognostic event even with preserved LV function; symptom improvement with diuretics does not change this prognostic significance 2
• Echocardiographic assessment can underestimate MR severity in late-systolic prolapse where regurgitation occurs only in very late systole 2
• The presence of moderate or greater residual MR at the time of surgery is the most important predictor of long-term repair failure 1
• Physical examination showing very late soft systolic murmur with no diastolic filling sound and clear lungs suggests only mild-to-moderate MR despite potentially misleading echo calculations 2