Myocarditis

Abstract

The JCS 2023 Guidelines on the Diagnosis and Treatment of Myocarditis classifies myocarditis as acute, chronic active, chronic, chronic inflammatory cardiomyopathy, or postmyocarditis cardiomyopathy. Endomyocardial biopsy is the gold standard for the diagnosis of myocarditis, but cardiac magnetic resonance imaging (MRI) has become increasingly important in recent years. In cases with suggestive symptoms, signs, and clinical course accompanied by elevated cardiac troponin levels, cardiac MRI findings that meet the Lake Louise criteria can be used to diagnose acute myocarditis without endomyocardial biopsy. However, endomyocardial biopsy is essential for the definitive diagnosis of chronic active myocarditis and chronic inflammatory cardiomyopathy. In this review, we provided an overview of the diagnosis, treatment, and management of myocarditis in accordance with the 2023 revised guidelines, including our own case studies. The diagnosis of myocarditis cannot be based on clinical course and noninvasive tests alone, and it needs to be confirmed by myocardial biopsy or cardiac MRI. A certain number of cases that were clinically diagnosed as dilated cardiomyopathy were chronic active myocarditis and chronic inflammatory cardiomyopathy. Appropriate diagnosis, treatment, and management of these patients are expected to improve the outcomes of severe heart failure in both childhood and adulthood.