Overview
Definition
A genetic disorder characterized by left ventricular hypertrophy (usually asymmetric and involving the septum) unexplained by abnormal loading conditions.
Epidemiology
Prevalence of 1 in 500. A leading cause of sudden cardiac death in young athletes.
Etiology & Risk Factors
- Autosomal dominant mutations in cardiac sarcomere genes (e.g., MYH7, MYBPC3)
Clinical Symptoms
- Often asymptomatic
- Dyspnea on exertion
- Chest pain
- Syncope (especially post-exertional)
- Palpitations
Clinical Approach
Diagnosis
- Echocardiogram (asymmetric septal hypertrophy, SAM - systolic anterior motion of the mitral valve)
- ECG (massive LVH, deep narrow 'dagger-like' Q waves in inferior/lateral leads)
- Auscultation: Systolic murmur that INCREASES with Valsalva/standing (decreased preload)
Management
- Beta-blockers (first-line to prolong diastole and decrease contractility)
- Non-DHP CCBs (Verapamil) if beta-blockers not tolerated
- Avoid volume depletion and pure vasodilators
- ICD placement if high risk for sudden cardiac death
- Surgical myectomy or alcohol septal ablation for severe outflow tract obstruction
Complications
- Sudden cardiac death (V-Fib)
- Atrial fibrillation
- Heart failure