Clinical Characteristics of Pediatric Myocarditis Stratified by Left Ventricular Ejection Fraction and Factors Associated with ECMO Support.

Pediatric myocarditis presents with heterogeneous clinical manifestations and may progress to severe cardiac dysfunction requiring advanced life support. This retrospective study included 78 children with clinically suspected myocarditis treated between January 2021 and December 2024. Children were stratified by left ventricular ejection fraction (LVEF) at admission and further analyzed according to the use of extracorporeal membrane oxygenation (ECMO). Children with LVEF <50% more frequently presented with gastrointestinal symptoms, shock, arrhythmias, organ dysfunction, and higher rates of pediatric intensive care unit (PICU) admission and ECMO support. Left ventricular ejection fraction <50%, arrhythmia, younger age, hypoalbuminemia, elevated lactate and myocardial injury biomarkers were associated with ECMO support. Reduced LVEF in pediatric myocarditis is associated with a higher risk of organ dysfunction and a greater need for advanced life support; ECMO support correlates with markers of myocardial injury and systemic hypoperfusion. These findings may help clinicians recognize high-risk patients early and guide timely escalation of life-support therapies.