Dilated Cardiomyopathy: A Novel BAG3 Mutation Associated with Aggressive Disease Progression and Ventricular Arrhythmias

We present the case of a 46-year-old man with a history of complex ventricular arrhythmias preceding the development of asymptomatic mild left ventricular dysfunction, who presented with acute-onset heart failure and was ultimately diagnosed with dilated cardiomyopathy. Genetic testing identified a novel, likely pathogenic mutation in exon 4 of the <i>BAG3</i> gene (NM_004281, c.1128del, (p.(Ser377AlafsTer47)), not previously reported in the literature. Given the presence of multiple clinical features indicative of a poor prognosis, he underwent prophylactic placement of a subcutaneous implantable cardioverter-defibrillator. The clinical presentation of this novel <i>BAG3</i> mutation suggests that it may be associated with a significant arrhythmic phenotype. This case underscores the importance of close follow-up and genetic testing in patients presenting with mild left ventricular dysfunction and ventricular arrhythmias.