Diagnosis of Arrhythmogenic Cardiomyopathy in a Young Patient With Recurrent Myocarditis: The Importance of Genetic Testing.

Genetic testing for cardiomyopathies has become a pivotal tool in diagnosing conditions with diverse and often overlapping clinical presentations. Arrhythmogenic cardiomyopathy (ACM), which affects approximately 1 in 5000 individuals, is a life-threatening condition associated with life-threatening arrhythmias and sudden cardiac death (SCD). While ACM typically presents with right- or left-sided heart failure, ventricular arrhythmias, or SCD, it can also manifest as acute or recurrent myocarditis. These inflammatory episodes, known as the "hot phase" of ACM, are less common but highly relevant in certain clinical contexts. We present the case of a 20-year-old male with recurrent episodes of acute myocarditis, confirmed by evidence of myocardial inflammation on cardiac magnetic resonance imaging (cMRI). Genetic testing revealed a pathogenic mutation in the desmoplakin (DSP) gene associated with ACM, raising the suspicion that the recurrent myocarditis episodes represent a "hot phase" of this inherited condition. In conclusion, this case underscores the importance of considering ACM in patients with recurrent myocarditis and highlights the role of genetic testing in uncovering underlying etiologies.