A 24-year-old man presents with sustained monomorphic ventricular tachycardia of left bundle branch block morphology with superior axis. MRI shows regional right ventricular akinesia with late gadolinium enhancement. Family history includes a sibling who died suddenly at 20 years. Which protein complex defect underlies this condition?

• A Sarcomeric proteins including beta-myosin heavy chain
• B Sarcolemmal calcium channel subunits
• C Desmosomal proteins including plakoglobin and desmoplakin ✓
• D Mitochondrial oxidative phosphorylation enzymes

Explanation

Arrhythmogenic right ventricular cardiomyopathy results from defective desmosomal proteins such as plakophilin-2, plakoglobin, and desmoplakin, leading to myocyte detachment, fibrofatty replacement, and ventricular arrhythmia. Left bundle branch block VT with superior axis points to RV origin. Sarcomeric mutations cause hypertrophic cardiomyopathy, calcium channel defects cause catecholaminergic polymorphic VT, and mitochondrial defects cause hypertrophic or dilated phenotypes.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.