Qingli Yang, Lijing Ye, Liting Wang, Yi Zhang, Yi Zhu, Jun Shen
Background: Fulminant myocarditis (FM) is a life-threatening inflammatory cardiac disease in children, frequently triggered by viral infections. Although mechanical circulatory support has improved short-term survival, data on viral etiology and long-term outcomes remain limited, particularly in Asian populations. Methods: We conducted a mixed retrospective-prospective analysis of pediatric FM patients at the Children's Hospital of Fudan University from 2015 to 2025. Clinical data from 2015 to 2023 were collected retrospectively, while data from 2024 onward were collected prospectively. Clinical data, microbiological findings (PCR and metagenomic next-generation sequencing), treatment strategies, and outcomes were extracted from electronic medical records. Follow-up data for survivors were collected through December 2025. Results: A total of 53 children with FM were included. Median age was 91.5 months; 43.4% were male, and 56.6% were female. Common presenting symptoms included fever (64.2%) and vomiting (56.6%). Microbiological evidence was identified in 11 patients (20.8%), with rhinovirus (5.7%) and influenza virus (5.7%) being the most frequent, followed by enterovirus (3.8%) in peripheral specimens. During hospitalization, 79.2% required mechanical ventilation, 64.2% received extracorporeal membrane oxygenation (ECMO), and 45.3% underwent continuous renal replacement therapy (CRRT). Intravenous immunoglobulin (IVIG) was administered to 84.9%. In-hospital mortality was 13.2% (7/53), and 17.0% (9/53) of patients were discharged against medical advice (DAMA). Among 35 followed patients (median 12.4 months), most achieved favorable cardiac recovery; however, persistent conduction abnormalities, structural cardiac changes, and neurological sequelae were observed in a minority. Conclusions: Pediatric FM carries substantial in-hospital morbidity and resource utilization, despite favorable recovery rates in most survivors. The low pathogen detection rate in peripheral blood and the lack of endomyocardial tissue sampling preclude definitive conclusions regarding the underlying etiology, whether active viral replication or immune-mediated injury predominates. Endomyocardial biopsy-based investigations are urgently needed to clarify the underlying pathobiology.