Management of patients with myocarditis and arrhythmogenic phenotype

Abstract Acute myocarditis (AM) is an inflammatory condition of the myocardium that may lead to severe complications, including acute heart failure and life-threatening ventricular arrhythmias (VAs). In-hospital VAs are estimated to affect 2.5% of adult patients with AM. Recent insights suggest a genetic predisposition to develop VA in a subset of patients with AM. This review will focus on arrhythmogenic manifestations of AM, highlighting risk stratification for VA after an acute episode and the contribution of genetic factors, emphasizing the need to integrate clinical, imaging, and genetic findings. In addition, prognostic information derived from cardiac magnetic resonance imaging will be discussed, pointing out the association between VA and the presence, extension, and septal localization of late gadolinium enhancement. The overlap between inherited arrhythmogenic and inflammatory cardiomyopathies will be explored, with specific attention to the identification of desmosomal gene variants, which are associated with recurrent myocarditis-like episodes and a higher risk of VA. Cardiac sarcoidosis, giant cell myocarditis, and immune checkpoint inhibitors-related myocarditis will be discussed as a paradigm of inflammatory cardiomyopathies with increased arrhythmic burden. Finally, the clinical challenges of managing patients with AM and arrhythmogenic presentation will be tackled, looking at indications for implantable cardioverter defibrillators after the acute phase.