Myocarditis is an inflammatory disease of the myocardium. Most cases of myocarditis are self-limiting, but if not treated promptly, it can progress to dilated cardiomyopathy. Dilated cardiomyopathy often begins insidiously. Once symptoms appear and the patient enters the stage of heart failure, the condition becomes very serious. Additionally, a minority of patients experience a fulminant onset, leading to acute decompensation or sudden death. Fulminant myocarditis and severe myocarditis progress quickly and have a high mortality rate, thus highlighting the dangers of myocarditis.