Hypertrophic Cardiomyopathy
A genetic condition causing abnormal thickening of the heart muscle, leading to breathing problems, chest pain, and a risk of sudden cardiac death.
Emergency Management: Ventricular Fibrillation. Requires immediate CPR and defibrillation.
Hypertrophic Cardiomyopathy (HCM) is an autosomal dominant genetic disorder characterized by unexplained left ventricular hypertrophy (LVH) ≥ 15 mm, often with asymmetric septal involvement and dynamic left ventricular outflow tract (LVOT) obstruction.
Detailed Overview
HCM is caused by sarcomere gene mutations leading to myocyte disarray and fibrosis. It causes diastolic dysfunction and is a leading cause of sudden cardiac death (SCD) in young athletes. Symptoms worsen when the LVOT gradient increases (due to increased contractility or decreased preload).
Epidemiology & Demographics
Prevalence is 1 in 500. It is the most common inherited heart disease.
Etiological Mechanism
Autosomal dominant mutations in sarcomere genes (MYBPC3, MYH7).
Primary Causes
Genetic mutations in cardiac sarcomere proteins
Mutant sarcomere proteins cause impaired contractility and compensatory gross hypertrophy. Histology shows profound myocyte disarray and interstitial fibrosis. In obstructive HCM, the thickened septum and systolic anterior motion (SAM) of the mitral valve create a dynamic LVOT gradient, impeding blood ejection and causing mitral regurgitation.
Diagnostic Criteria & Guidelines
Echocardiogram showing unexplained LV wall thickness ≥ 15 mm (or ≥ 13 mm with positive family history).
Non-vasodilating beta-blockers: Metoprolol succinate 50-200 mg daily to decrease heart rate and contractility, reducing the LVOT gradient.
Second-Line & Adjunctive Therapy
Mavacamten (cardiac myosin inhibitor) 5 mg PO daily. Non-dihydropyridine CCBs (Verapamil) if beta-blockers contraindicated.
Surgical & Procedural Management
Surgical Septal Myectomy or Alcohol Septal Ablation for severe refractory LVOT obstruction. Implantable Cardioverter-Defibrillator (ICD) for SCD prevention.
Patient Counseling & Advice
Strictly avoid pure vasodilators (nitrates) or inotropes (digoxin). Ensure first-degree relatives get echocardiographic screening.
Follow-Up & Monitoring Schedule
Annual Echo and 48-hour Holter monitor. Periodic reassessment of 5-year SCD risk score.
Preventive Strategies
Primary prevention of SCD via ICD if high-risk criteria are met.
Normal life expectancy for most. Annual mortality ~1% mainly due to heart failure or SCD.