Prior myocarditis and ventricular arrhythmias: The importance of scar pattern

Background: Multiple studies have addressed the importance of anteroseptal scar in patients with nonischemic cardiomyopathy. However, this pattern has never been fully evaluated in patients with prior myocarditis. Objective: The purpose of this study was to evaluate whether anteroseptal scar is associated with worse outcome in patients with prior myocarditis and how it affects the efficacy of catheter ablation (CA). Methods: This was a retrospective study of consecutive patients with prior myocarditis and arrhythmic presentation. Cardiac magnetic resonance and electroanatomic voltage mapping were used to identify the scar pattern. Patients were referred for either CA or escalated antiarrhythmic drug (AAD) therapy. The main outcome was ventricular arrhythmia (VA)–free survival according to the presence of anteroseptal scar. Results: A total of 144 consecutive patients with prior myocarditis were included. Mean age was 42.1 ± 14.9 years, and 58% were men. Ejection fraction was normal in 73% of patients. Anteroseptal scar was present in 44% of cases. Sixty-one patients (42%) underwent CA. Overall, at 2-year follow-up, VA-free survival was 77% in the CA group. After CA, the mean number of AADs taken by each patient decreased from 1.8 to 0.9 per day (p<0.001). The presence of anteroseptal scar was found to be an independent predictor of VA relapse both in patients treated with CA (hazard ratio [HR] 3.6; 95% confidence interval [CI] 1.1–11.4; P =.03) and in the overall population (HR 2.0; 95% CI 1.2–3.5; P =.02). Conclusion: In patients with prior myocarditis and VA, the presence of anteroseptal scar negatively predicts outcomes irrespective of treatment strategy.