Clinical profiling and Outcomes of Viral Myocarditis manifesting with Ventricular Arrhythmias

Clinical features and risk stratification of patients with viral myocarditis (VM) complicated by ventricular arrhythmias (VA) are incompletely understood. We aim to describe arrhythmia patterns and outcomes in patients with VM and early-onset VA. We present a single center study, enrolling patients with VM proven by endomyocardial biopsy, and evidence of VA within 24 hours of hospitalization. The incidence of major adverse events (MAE), including all-cause death, severe heart failure, advanced atrioventricular blocks, or major VA, was evaluated during a 24-month follow-up (FU), and compared with a matched group of virus-negative myocarditis. Of patients with VM (n=74, mean age 47±16 years, 66% males, LVEF 51±13%), 20 (27%) presented with major VA (VT/VF), and 32 (44%) had polymorphic VA. Patients with polymorphic VA more commonly had evidence of ongoing systemic infection (24/32 vs. 10/42, p=0.004) and experienced greater occurrence of MAE at discharge (15/32 vs. 2/42, p<0.001). However, the incidence of MAE during FU was higher in patients with monomorphic VA compared to those with polymorphic VA (17/42 vs. 2/28, p=0.002). Patients with monomorphic VA displayed frequently signs of chronic cardiomyopathy, and had outcomes comparable with virus-negative myocarditis (Log rank p=0.929). Presentation with VT/VF was independently associated with MAE (at discharge: HR 4.7, 95%CI 1.6-14.0, p=0.005; during FU: HR 6.3, 95%CI 2.3-17.6, p<0.001). In patients with VM, polymorphic VA point to ongoing systemic infection and early adverse outcomes, whereas monomorphic VA suggest chronic cardiomyopathy and greater incidence of MAE during FU. Presentation with VT/VF is independently associated with MAE.