Incidence and characteristics of tachyarrhythmias in patients with acute myocarditis

Purpose: Acute myocarditis may be associated with life threatening tachyarrhythmias and a poor outcome. The purpose of this study was to define the incidence and clinical characteristics of tachyarrhythmias in young patients with acute myocarditis. Methods: We retrospectively reviewed all patients 25 years of age who received a clinical or biopsy proven diagnosis of acute myocarditis from October 2002 to December 2012 at a tertiary care institution. Clinically significant tachyarrhythmias (CSTs) were defined as requiring treatment with antiarrhythmic medications. Results: Seventy patients met the inclusion criteria (76% male, 22.4±3.5 years). The diagnosis of myocarditis was made clinically with 43% (n=30) confirmed with biopsy. Eighteen patients required intubation and 38 were treated with inotropes. There were 18 patients with CSTs (4 supraventricular, 3 non-sustained VT, 11 sustained VT/VF). Cardioversion or defibrillation was required in 10/18 (55%). Patients with CSTs were more likely to have been treated with inotropes (16/18, 89%) than those without tachyarrhythmias. Twenty patients required mechanical support (IABP, n=16, ECMO n=3, Impella n=1). Patients with CSTs were more likely to require mechanical support as compared to patients without. Twenty-two patients were transplanted and five died. Patients with CSTs were more likely to experience death or transplant as compared to patients without CSTs. When controlling for age and ejection fraction, CSTs remain a predictor of death or transplant. Left ventricular ejection fraction was an independent predictors of CSTs, while gender, CRP, ESR, and troponins were not. Conclusion: Patients with acute myocarditis have a considerable incidence of clinically significant tachyarrhythmias. The morbidity and mortality is significantly higher in patients with tachyarrhythmias.