Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young athletes. The underlying histological finding that predisposes to lethal arrhythmias in HCM is best described as:
- A Massive coagulative necrosis with replacement fibrosis of the septal area
- B Myocardial amyloid deposition causing restrictive physiology
- C Inflammatory infiltrate with granuloma formation in the conduction system
- D Myofibre disarray — haphazard arrangement of myocytes with disorganised myofibrillar architecture and interstitial fibrosis ✓
Explanation
The hallmark histological finding of HCM is myofibre disarray: myocytes are arranged in chaotic, interwoven patterns perpendicular to each other, with disorganised myofibrillar architecture within individual cells, and surrounded by interstitial and replacement fibrosis. This disarray creates abnormal electrical conduction pathways (re-entry circuits) predisposing to ventricular tachycardia/fibrillation. HCM results from mutations in sarcomeric proteins (most commonly beta-myosin heavy chain and myosin binding protein C), and myofibre disarray is present in >95% of patients.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.