Background: Acute myocarditis, a primary inflammatory cardiac disease commonly caused by viral infection, is an important cause of morbidity and mortality in children. Data obtained from forensic studies found an incidence of 15–33% for acute myocarditis in sudden deaths in the pediatric age group. Currently, there is a lack of data regarding the incidence and factors associated with short-term outcomes in pediatric patients admitted for acute myocarditis.

The aim of the study was to identify predictors for in-hospital mortality in a pediatric population admitted with acute myocarditis.

Material and methods: We conducted a retrospective observational cohort study that included 21 patients admitted for acute myocarditis. Clinical, laboratory, ECG, and imaging data acquired via 2D transthoracic echocardiography and cardiac magnetic resonance imaging were collected from the medical charts of each included patient. The primary end-point of the study was all-cause mortality occurring during hospitalization (period ranging from 10 to 14 days). The study population was divided into 2 groups according to the occurrence of the primary end-point.

Results: The mean age of the study population was 99.62 ± 77.25 months, and 61.90% (n = 13) of the patients were males. The in-hospital mortality rate was 23.9% (n = 5). Patients in the deceased group were significantly younger than the survivors (55.60 ± 56.18 months vs. 113.4 ± 78.50 months, p = 0.039). Patients that had deceased presented a significantly higher level of LDH (365 ± 21.38 U/L vs. 234.4 ± 63.30 U/L, p = 0.0002) and a significantly higher rate of ventricular extrasystolic dysrhythmias (60% vs. 6.25%, p = 0.02, OR: 22.5, 95% CI: 1.5–335) compared to survivors. The 2D echocardiography showed that patients that had deceased presented more frequently an impaired left ventricular ejection fraction (<30%) (p = 0.001) and a significantly higher rate of severe mitral regurgitation (p = 0.001) compared to survivors.

Conclusions: The most powerful predictors for in-hospital mortality in pediatric patients admitted for acute myocarditis were the presence of ventricular extrasystolic dysrhythmias on the 24h Holter ECG monitoring, impaired left ventricular systolic function (LVEF <30%), the presence of severe mitral regurgitation, and confirmed infection with Mycoplasma pneumoniae.