What is the leading cause of death in hypertrophic obstructive cardiomyopathy?

• A. Ventricular fibrillation
• B. Myocardial infarction due to coronary occlusion
• C. Stroke
• D. Heart failure

Answer: (A)

In hypertrophic obstructive cardiomyopathy, the main threat to life is sudden cardiac death from malignant ventricular arrhythmias. The thickened, fibrotic heart muscle creates an electrical substrate that promotes re-entrant and triggered ventricular tachyarrhythmias. When a ventricular fibrillation event occurs, organized contraction is lost and the patient can collapse suddenly, which is the most common fatal mechanism, especially in younger individuals during exertion. Other potential fatal paths—myocardial infarction from blocked coronaries, stroke from emboli, or progressive heart failure—do occur but are less likely to be the immediate cause of death in this condition. The emphasis is on the risk of sudden death from ventricular fibrillation due to the structural and electrical abnormalities characteristic of HCM.