Acute Myocarditis: From Pathophysiology to Risk-Stratified Management-A Clinical Review

Acute myocarditis is an inflammatory disease of the myocardium with an annual incidence of 4-14 per 100,000 individuals, predominantly affecting young adults. Its clinical features are frequently nonspecific, mimicking acute coronary syndrome, which makes early recognition and management challenging. The disease results from infectious (predominantly viral) and noninfectious triggers, including autoimmune disorders, immune checkpoint inhibitors and mRNA vaccines. Pathophysiology involves a dysregulated interplay between innate immunity and adaptive immunity.

Presentation is typically dominated by chest pain, with dyspnea and syncope reported less frequently. Cardiac magnetic resonance (CMR), with the 2018 updated Lake Louise criteria, has become the cornerstone of noninvasive diagnosis, whereas endomyocardial biopsy (EMB), in experienced centres, remains the gold standard for histological characterization and guiding immunosuppressive therapy.

Uncomplicated myocarditis usually resolves spontaneously. However, approximately 25% of patients with myocarditis have left ventricular systolic dysfunction, ventricular arrhythmias or acute heart failure. Mortality ranges from 1% to 7%, depending on presentation, aetiology and specific populations. Treatment centers on guideline-directed heart failure therapy, with immunosuppression reserved for complicated presentations and virus-negative, autoimmune or histologically specific subtypes. Mechanical circulatory support is critical in fulminant cases, where mortality is high.

This clinical review synthesizes recent guideline updates and emerging trial data, primarily from literature published in the past 10 years, to support a phenotype-driven approach to acute myocarditis, in which management is guided by clinical severity, suspected aetiology, selective use of CMR and EMB and targeted therapy. Ongoing trials investigating corticosteroids, targeted biologics and novel therapies may further refine personalized immunomodulatory strategies.