What does a click heard on auscultation indicate and how is it managed?

Midsystolic Click on Auscultation: Diagnosis and Management

A midsystolic click heard on auscultation is most commonly indicative of mitral valve prolapse (MVP) and requires echocardiographic confirmation for definitive diagnosis and risk stratification. 1

Diagnostic Significance of a Midsystolic Click

A midsystolic click is a high-pitched sound of short duration that occurs during systole and represents the primary auscultatory feature of mitral valve prolapse syndrome. This sound results from the sudden tensing of the mitral valve apparatus as the leaflets prolapse into the left atrium during systole. 1

Key characteristics of the midsystolic click include:

• One or more clicks may be present
• Varies in intensity and timing according to left ventricular loading conditions
• Often followed by a late systolic murmur (medium to high-pitched, loudest at cardiac apex)
• The murmur may have a musical or honking quality
• Dynamic changes with positional maneuvers 1

Dynamic Auscultation

Dynamic auscultation is particularly useful for establishing the diagnosis of MVP:

• Standing position: Decreases end-diastolic volume, causing earlier prolapse in systole, with the click-murmur complex occurring shortly after the first heart sound
• Squatting position: Increases ventricular volume, reduces myocardial contractility, increases LV afterload, causing the click-murmur complex to move toward the second heart sound 1

Diagnostic Evaluation

Initial Assessment

1. Physical examination: The primary diagnostic evaluation for MVP is a thorough physical examination focusing on the characteristic midsystolic click and potential late systolic murmur 1

2. Echocardiography: Two-dimensional and Doppler echocardiography is the most useful noninvasive test for defining MVP 1, 2

   • Class I recommendation: Echocardiography is indicated for diagnosis of MVP and assessment of mitral regurgitation, leaflet morphology, and ventricular compensation in asymptomatic patients with physical signs of MVP 1

Echocardiographic Diagnostic Criteria

• Valve prolapse of 2 mm or more above the mitral annulus in the long-axis parasternal view
• Leaflet coaptation occurring on the atrial side of the annular plane
• Leaflet thickness of 5 mm or more (indicates higher risk) 1, 2

Risk Stratification

High-risk features in MVP include:

• Leaflet thickness ≥5 mm
• Moderate to severe mitral regurgitation
• Left ventricular dysfunction (EF ≤60%)
• Left atrial enlargement
• Flail leaflet 2

Management Approach

Asymptomatic Patients

1. Reassurance: A major component of management for MVP patients with mild symptoms, as most have a benign prognosis 2, 3

2. Follow-up recommendations:

   • Asymptomatic patients with no/mild mitral regurgitation: Clinical evaluation every 3-5 years 2
   • Patients with high-risk features: Annual follow-up with serial echocardiography 2

3. Regular exercise and normal lifestyle should be encouraged in most patients with MVP 2

Symptomatic Patients

1. Symptom management:

   • Beta blockers may be used to manage tachyarrhythmias and increased adrenergic symptoms 2
   • Volume expansion, support stockings, and mineralocorticoid therapy or clonidine may be used for orthostatic symptoms 2

2. Antiplatelet therapy:

   • Aspirin therapy (75-325 mg per day) is recommended for symptomatic patients with MVP who experience cerebral transient ischemic attacks 2

3. Anticoagulation:

   • Warfarin therapy for patients with MVP and atrial fibrillation who are older than 65 years, have hypertension, have mitral regurgitation murmur, or have a history of heart failure 2

Complications and Surgical Intervention

MVP can lead to complications including:

• Mitral regurgitation
• Atrial fibrillation
• Congestive heart failure
• Endocarditis
• Ventricular arrhythmias
• Sudden cardiac death (rare, <2% of cases) 1, 2

Surgical intervention (repair preferred over replacement) may be indicated for:

• Symptomatic severe mitral regurgitation
• Asymptomatic severe mitral regurgitation with LV dysfunction (EF <60%)
• LV end-systolic dimension ≥40 mm
• New onset atrial fibrillation
• Pulmonary hypertension (pulmonary artery systolic pressure >50 mmHg) 2

Common Pitfalls to Avoid

1. Overdiagnosis: Not all systolic clicks are due to MVP; careful dynamic auscultation and echocardiographic confirmation are essential 2

2. Misattribution of symptoms: MVP is not associated with nonspecific symptoms like atypical chest pain, dyspnea, anxiety or panic attacks 4

3. Unnecessary anticoagulation: Only prescribe for patients with appropriate indications to avoid bleeding risks 2

4. Missed diagnosis: MVP can be present without classic auscultatory findings, and clicks may be intermittent and variable 1

5. Inadequate follow-up: Patients with high-risk features require closer monitoring 2