Rate and patient features associated with recurrence of acute myocarditis.

Abstract

BACKGROUND: Rate and patient features associated with recurrence after acute myocarditis are largely unknown. METHODS AND RESULTS: First recurrence of acute myocarditis was studied in 1662 patients aged 16-70 years using a registry data of 29 hospitals in Finland (median follow-up 4.5 years). Matched intoxication patients served as controls. Incidence rate of first time hospitalization due to acute myocarditis was 5.52 (CI 5.26-5.79) per 100,000 person-years during 2001-2008. During the first 30 days 5.5% (CI 3.5-4.4%) of patients were re-admitted to hospital with acute myocarditis (p<0.0001 vs. controls). After 30 days, recurrence rate was 7.0% (CI 5.7-8.6%; p<0.0001 vs. controls). Acute myocarditis recurred after 365 days in 4.7% (CI 3.2-6.7%) of patients (p<0.0001 vs. controls). During the whole follow-up, recurrence rate was 10.3% (CI 8.8-12.1%; p<0.0001 vs. controls) with median recurrence time of 34.5 days. Prolonged (>7 days) initial admission was associated with recurrences during (HR 2.9; CI 1.6-5.2) and after first month (HR 1.8; CI 1.2-3.2), and overall (HR 2.0; CI 1.3-3.2). Ventricular arrhythmia at initial occurrence was associated with recurrence after 30 days (HR 8.6; CI 2.5-30.1), after 1 year (HR 22.6; CI 2.5-201.4) and overall (HR 6.7; CI 2.3-6.7). Other features associated with recurrence were younger age (>365 days), inflammatory bowel disease (during first month), and chronic pulmonary disease (≥ 30 days). CONCLUSIONS: Acute myocarditis reoccurs in a significant proportion of patients. Prolonged initial admission, ventricular arrhythmias, younger age, inflammatory bowel disease and chronic pulmonary disease are associated with recurrences at different phases after acute myocarditis.