Novel SCN5A variant associated with flecainide-responsive multifocal ventricular arrhythmia and recovered cardiomyopathy.

Multifocal Ectopic Purkinje-related Premature Contractions (MEPPC) is a rare genetic arrhythmogenic syndrome caused by gain-of-function mutations in the SCN5A gene, leading to frequent multifocal premature ventricular contractions and risk of cardiomyopathy. We report a case highlighting the diagnostic and therapeutic challenges associated with unrecognized MEPPC. A 27-year-old woman presented with highly symptomatic ventricular and supraventricular arrhythmias and severe left ventricular dysfunction, refractory to conventional therapy and ablation. Initiation of flecainide resulted in immediate arrhythmia suppression and full recovery of cardiac function. Genetic testing revealed two SCN5A variants: a novel likely pathogenic p.(Val215Ala) located in a known MEPPC hotspot, and p.(Phe1570Cys), a variant with known loss-of-function properties, unlikely to be causative in MEPPC but potentially modulating the phenotype. This report underscores the importance of early recognition of MEPPC based on arrhythmic patterns and the critical role of targeted genetic testing in optimizing treatment strategies.