Outcomes of Myocarditis in Patients with Normal Left Ventricular Systolic Function on Admission

The objective of this study was to describe a cohort of patients with clinical myocarditis and normal left ventricular (LV) systolic function on admission. A retrospective chart review at seven tertiary pediatric hospitals identified patients aged < 19 years admitted with an ICD-9 code of myocarditis between 2008 and 2012. Patients were excluded if admission LV systolic ejection fraction was < 50%, fractional shortening (FS) was < 28% or if the admitting or consulting cardiologist did not suspect myocarditis. A total of 75 patients met inclusion criteria. The median age was 15.5 years with an Interquartile Range (IQR) of 13.6-16.6. 33% were female. Patients presented most commonly with chest pain (75%) and dyspnea (24%). On admission, median B-type natriuretic peptide (BNP) was 132 pg/mL (IQR 57-689) and median troponin I (TnI) was 8.4 ng/mL (IQR 2.0-20.3). Electrocardiogram revealed ST elevation in the majority (55%). Magnetic resonance imaging was obtained on 40%, with 63% of those showing evidence of inflammation. Therapies included inotropic support (15%), mechanical ventilation (12%), antiarrhythmic medications (9%), and Extracorporeal Membrane Oxygenation (5%). Those with poor outcomes were noted to have significantly higher BNP, TnI, and creatine kinase levels on presentation. One patient was transplanted and 35% were discharged on heart failure medications. At one year follow-up one patient had died of unspecified causes, 15% required readmission for cardiac reasons, and 21% continued on heart failure medications. The risk associated with clinical myocarditis in the setting of normal ventricular function at presentation may be higher than previously suspected.