Usefulness of arrhythmias as predictors of death and resource utilization in children with myocarditis.

Myocarditis in children can result in significant morbidity and mortality, yet limited prognostic data exist. The aim of this study was to test the hypothesis that pediatric patients with arrhythmias during hospitalization for acute myocarditis have worse outcomes and increased resource utilization. A retrospective study using the Pediatric Health Information System database was performed to examine the effects of clinically significant arrhythmias on in-hospital mortality, length of stay, and costs per day. Data were obtained for children ≤18 years of age, discharged from January 1, 2004 to March 31, 2013, with a diagnosis of myocarditis. Clinically significant tachyarrhythmia was defined as supraventricular tachycardia, atrial fibrillation or flutter, or ventricular tachycardia or fibrillation in patients receiving antiarrhythmic medications or cardioversion. Clinically significant bradyarrhythmia was defined as second-degree, complete, or other heart block for which a pacemaker was placed. Multivariable analyses were performed. A total of 2,041 subjects with myocarditis were identified. Tachyarrhythmias were reported in 234 (11.5%) and bradyarrhythmias in 22 (1.1%). Overall mortality was 8.7%. In multivariable analyses, after considering the effects of gender, age at admission, geographic region, year and month of admission, presence of congenital heart disease or an identified virus, and use of steroids, nonsteroidal anti-inflammatories, or inotropes, and after controlling for clustering by institution, tachyarrhythmias were associated with a 2.3 times increase in the odds of mortality (95% confidence interval 1.6 to 3.3, p < 0.001), a 58% increase in length of stay (95% confidence interval 38% to 82%, p < 0.001), and a 28% increase in costs per day (95% confidence interval 15% to 43%, p < 0.001). Bradyarrhythmia was not associated with mortality, length of stay, or costs per day. In conclusion, tachyarrhythmias are associated with significant increases in mortality and resource utilization in children with myocarditis.