Pediatric acute myocarditis: current evidence and practical recommendations.

Abstract

Acute myocarditis (AM) in children and adolescents remains a diagnostic and therapeutic challenge because of its heterogeneous presentation, overlap with dilated cardiomyopathy, and potential for fulminant deterioration, with approximately 5.9% risk of early mortality. We performed a narrative review integrating contemporary guidelines, consensus documents, and weighted analyses from systematically selected large pediatric cohorts to summarize current evidence on epidemiology, diagnosis, risk stratification, and treatment. Pediatric AM shows a male predominance and a bimodal age distribution. Early recognition is often difficult because initial manifestations may be non-specific and the differential diagnosis varies across age groups. Younger children more often present with dilated phenotypes and prominent gastrointestinal symptoms, frequently reflecting low cardiac output and systemic congestion, whereas adolescents may present with an uncomplicated phenotype characterized by chest pain and regional wall motion abnormalities. Severe disease remains a relevant burden, with fulminant myocarditis accounting for approximately one quarter of cases and carrying markedly higher mortality. Initial evaluation should therefore focus on early risk stratification, integrating clinical severity, biomarkers, electrocardiogram, echocardiography, and etiological testing. This approach may help identify high-risk viral phenotypes associated with enteroviruses or parvovirus B19, while also recognizing systemic inflammatory syndromes such as multisystem inflammatory syndrome in children, which may mimic AM but usually responds to timely immunomodulatory treatment. We propose a practical risk-based strategy that classifies patients into low-, intermediate-, and high-risk groups to guide monitoring, referral, cardiac magnetic resonance, endomyocardial biopsy, and therapy. High-risk patients require early referral to tertiary centers with pediatric intensive care, cardiac surgery, and temporary mechanical circulatory support availability. Treatment should be individualized according to risk, ranging from supportive care to mechanical circulatory support, transplant evaluation, and selected immunomodulation. Prospective registries and randomized trials are needed to validate risk-based pathways and define evidence-based therapies.