Post-discharge arrhythmic risk stratification of patients with acute myocarditis and life-threatening ventricular tachyarrhythmias.

Background The outcomes of patients presenting with acute myocarditis and life-threatening ventricular tachyarrhythmias (LT-VA) are unclear. The aim of this study was to assess incidence and predictors of recurrence of major arrhythmic events (MAEs) after hospital discharge in such patients. Methods and results We retrospectively analysed 156 patients (median age 44 years; 77% males) discharged with a diagnosis of acute myocarditis and LT-VA from 16 hospitals worldwide. Diagnosis of myocarditis was based on histology or on the combination of increased markers of cardiac injury and cardiac magnetic resonance (CMR) Lake Louise criteria. MAEs were defined as the relapse, after discharge, of sudden cardiac death (SCD) or ventricular fibrillation defibrillated successfully or sustained ventricular tachycardia (sVT) requiring implantable cardioverter-defibrillator therapy or synchronized external cardioversion. Median follow-up period was 23 months (first to third quartile [Q1-Q3] 7-60). Fifty-eight (37.2%) patients experienced MAEs after discharge, at a median time of 8 months (Q1-Q3 2.5-24.0 months; 60.3% of MAEs within the first year). At multivariable Cox analysis, variables independently associated to MAEs were presentation with sVT (hazard ratio [HR] 2.90, 95% confidence interval [CI] 1.38-6.11); late gadolinium enhancement (LGE) involving ≥2 myocardial segments (HR 4.51, 95% CI 2.39-8.53); and absence of positive short-tau inversion recovery (STIR) (HR 2.59, 95% CI 1.40-4.79) at first CMR. Conclusions Among patients discharged with the diagnosis of myocarditis and LT-VA, 37.2% had recurrences of MAEs during follow-up. Initial CMR pattern and sVT at presentation stratify the risk of arrhythmic recurrence.