Viral myocarditis and the subsequent immune response to injury it elicits are a major cause of acute and chronic nonischemic dilated cardiomyopathy. Clinical presentation in myocarditis varies widely from asymptomatic electrocardiographic or laboratory findings to fulminant heart failure. Although histological examination, usually of myocardium obtained by endomyocardial biopsy, is required to confirm a diagnosis of myocarditis, patients may at times be treated based on a possible or probable diagnosis. Cardiac magnetic resonance imaging using a combination of T2- and T1-weighted sequences has a high sensitivity and specificity for myocarditis. Patients with acute myocarditis frequently improve with standard heart failure care, but occasionally require mechanical circulatory support. There is a growing interest in and use of immunomodulatory and antiviral therapies for select patients with chronic symptomatic cardiomyopathy despite optimal medical management...