Question

Young male died during exercise. History of similar history in a sibling. On gross morphology: septal thickening was seen. Most common cause of death?

• A. DCM
• B. RCM
• C. HOCM
• D. Viral Myocarditis

Hint:

Young athlete + sudden death on exertion + family history + asymmetrical septal hypertrophy = the classic sarcomeric cardiomyopathy.

Answer 1

The Correct Option is C

Mechanism-first approach. Start from the autopsy finding that anchors the diagnosis: septal thickening. Asymmetrical hypertrophy of the interventricular septum is the structural signature of Hypertrophic Cardiomyopathy. Layer onto this the two clinical anchors - sudden death triggered by exertion and a similarly affected sibling - and the genetics fall into place: this is an autosomal dominant sarcomere disease (commonly $\beta$-myosin heavy chain or myosin-binding protein C mutations).

Why exercise kills in HOCM: the thickened septum narrows the left ventricular outflow tract, and the chaotically arranged (disarrayed) myocyte fibres form a substrate for re-entrant ventricular tachyarrhythmias. Under the catecholamine surge of exercise, contractility rises and outflow obstruction worsens, tipping the heart into ventricular fibrillation - the leading cause of sudden cardiac death in young athletes.

Eliminating the rest: a dilated, baggy heart points to Dilated Cardiomyopathy; a rigid ventricle with prominent atria points to Restrictive Cardiomyopathy; a flabby heart with inflammatory infiltrate points to Viral Myocarditis. None of these produce focal asymmetrical septal hypertrophy in a young patient with a positive family history.

Hence the answer is HOCM (Option C).