Long-Term Arrhythmic Risk Assessment in Biopsy-Proven Myocarditis

OBJECTIVES This study sought to assess long-term arrhythmic risk in patients with myocarditis who received an implantable cardioverter-defibrillator (ICD). BACKGROUND The arrhythmic risk of patients with myocarditis overtime remains poorly known. METHODS The study enrolled 56 patients with biopsy-proven myocarditis who received an ICD for either primary (57%) or secondary prevention (43%) according to current guidelines. Clinical characteristics, biopsy findings, electrophysiological data from endocardiat 3-dimensional etectroanatomic voltage mapping, and device interrogation data were analyzed to detect arrhythmic events overtime. Coronary angiography excluded significant coronary artery disease in all patients. RESULTS At a mean follow-up of 74 +/- 60 months (median 65 months), 25 (45%) patients had major ventricular arrhythmias treated by ICD intervention (76% being terminated by ICD shock and 24% by antitachyarrhythmia burst pacing). At multivariable analysis, the presence of sustained ventricular tachycardia on admission (hazard ratio: 13.0; 95% confidence interval: 2.0 to 35.0; p = 0.032) and the extension of the areas of tow potentials at the bipolar endocardial mapping (hazard ratio: 1.19; 95% confidence interval: 1.04 to 1.37; p = 0.013) were the only independent predictors of appropriate ICD interventions. A cutoff value of 10% of abnormal bipolar area at etectroanatomical ventricular mapping discriminated patients with appropriate ICD interventions with a sensitivity of 89% and a specificity of 85%. CONCLUSIONS The study demonstrates that the prevalence of life-threatening ventricular arrhythmias in patients with myocarditis receiving an ICD according to current guidelines is high and the arrhythmic risk persists late overtime. Etectroanatomical ventricular mapping may be a useful toot to identify patients at greater arrhythmic risk. (C) 2020 by the American College of Cardiology Foundation.