Left-Dominant Arrhythmogenic Cardiomyopathy in a Young Athlete: Silent Danger on the Pitch.

BACKGROUND

Arrhythmogenic left ventricular cardiomyopathy (ALVC) may present with a myocarditis-like inflammatory "hot phase" and carries the risk of ventricular arrhythmias.

CASE SUMMARY: A 21-year-old athlete presented with hemifacial and arm paresthesia and chest discomfort. He had parietal ischemic lesions, elevated high-sensitivity I troponin, left ventricle (LV) dilation, apical hypokinesia, apical thrombus, and multifocal nonischemic late gadolinium enhancement with edema. A cardioembolic stroke due to myocarditis with an LV thrombus was assumed. However, he had progressive LV remodeling with persistent late gadolinium enhancement. Endomyocardial biopsy showed low-grade inflammation. Genetic testing identified a pathogenic MYBPC3 variant. The patient declined exercise restriction and experienced exercise-triggered ventricular fibrillation. A subcutaneous implantable cardioverter-defibrillator was inserted, and he remained asymptomatic.

DISCUSSION: The presentation and longitudinal course supported ALVC rather than myocarditis.

TAKE-HOME MESSAGES: ALVC can mimic myocarditis and may be unmasked by exercise exposure. Serial cardiac magnetic resonance, endomyocardial biopsy, and genetic testing can confirm the diagnosis.