Inflammation as a Predictor of Recurrent Ventricular Tachycardia After Ablation in Patients With Myocarditis

BACKGROUND Little is known about the risk stratification of patients with myocarditis undergoing ventricular tachycardia (VT) ablation. OBJECTIVES This study sought to describe VT ablation results and identify factors associated with arrhythmia recurrences in a cohort of patients with myocarditis. METHODS The authors enrolled 125 consecutive patients with myocarditis, undergoing VT ablation. Before ablation, disease stage was evaluated, to identify active (AM) versus previous myocarditis (PM). The primary study endpoint was assessment of VT recurrences by 12-month follow-up. Predictors of VT recurrences were retrospectively identified. RESULTS All patients (age 51 +/- 14 years, 91% men, left ventricular ejection fraction 52% +/- 9%) had history of myocarditis diagnosed by endomyocardial biopsy (59%) and/or cardiac magnetic resonance (90%). Furthermore, all had multiple episodes of drug-refractory VTs. Multimodal pre-procedural staging identified 47 patients with AM (38%) and 78 patients with PM (62%). All patients showed low-voltage areas (LVA) at electroanatomical map (97% epicardial or endoepicardial); of them, 25 (20%) had wide borderzone (WBZ, constituting >50% of the whole LVA). VT recurrences were documented in 25 patients (20%) by 12 months, and in 43 (34%) by last follow-up (median 63 months; interquartile range: 39 to 87). At multivariable analysis, AM stage was the only predictor of VT recurrences by 12 months (hazard ratio: 9.5; 95% confidence interval: 2.6 to 35.3; p < 0.001), whereas both AM stage and WBZ were associated with arrhythmia recurrences anytime during follow-up. No VT episodes were found after redo ablation was performed in 23 patients during PM stage. CONCLUSION Our findings suggest that VT ablation should be avoided during AM, but is often of benefit for recurrent VT after the acute phase of myocarditis. (C) 2020 by the American College of Cardiology Foundation.