Neonatal Cardiac Dilation and Dysfunction: Time to Look in the Genes.

Cardiomyopathy is a disease of the myocardium that can present with ventricular hypertrophy, dilation, or dysfunction and subsequently result in clinical heart failure. Dilated cardiomyopathy is the most common phenotype; however, it can be difficult to differentiate from myocarditis, particularly in neonates. Important causes of ventricular dysfunction in the pediatric population range from primary cardiomyopathies that affect the structure or function of the myocardium to systemic diseases that lead to secondary myocardial injury. We describe a term newborn who presented with a cardiac murmur and cyanotic spell and subsequently was found to have biventricular dysfunction on echocardiogram. Due to a positive respiratory viral panel for enterovirus, the patient was thought to have viral myocarditis; however, biomarkers revealed no evidence of systemic or myocardial inflammation on laboratory investigation. Furthermore, severe right ventricular dilation was present, which was less consistent with myocarditis. A primary cardiomyopathy was suspected, and genetic testing revealed a likely pathogenic variant of the ACTC1 gene. This case demonstrates the diagnostic dilemma of determining the etiology in neonatal cardiomyopathy and highlights the utility of genetic testing for diagnostic and prognostic information in such clinical scenarios.