[I-AEPCJS-03] Biopsy-proven Chronic Active Myocarditis in Children
Myocarditis is a group of inflammatory diseases involving the myocardium, and manifests a broad spectrum of clinical course. The concepts and definitions of chronic myocarditis, chronic inflammatory cardiomyopathy, and inflammatory dilated cardiomyopathy have not been standardized internationally. In particular, there is discrepancy in the definitions between Japan and Western countries, causing some confusion. In 2023 Japanese Guideline on the diagnosis and treatment of myocarditis, “chronic active myocarditis” has been redefined as a condition of myocardial inflammation persisting for ≥30 days and accompanied by cardiomyocyte injury including myocardial necrosis, which described as “chronic myocarditis” in the previous Japanese guidelines (1996, 2004, and 2009). Heart failure and arrhythmias often occur, presenting dilated cardiomyopathy-like features. In some cases, chronic active myocarditis develops subclinically and follows a chronic course, whereas in others it shows persistence and prolongation of acute myocarditis. We present eleven pediatric patients with biopsy-proven chronic active myocarditis in our institute, and discuss their clinical courses, therapies, prognoses, and the management of chronic active myocarditis.