Myocarditis

Abstract

This chapter evaluates myocarditis, which is a rare, potentially deadly, and often underdiagnosed cause of acute or chronic heart failure that primarily affects children and younger adults. Historically, the diagnosis of myocarditis was confirmed by histologic analysis of endomyocardial biopsy (EMB) specimens with findings of an inflammatory cellular infiltrate of the myocardium with or without myocyte necrosis and/or degeneration of adjacent myocytes. The type of inflammatory infiltrate, its distribution in cardiac tissue, and the degree of myocardial injury help construct the differential diagnosis. Clinically, myocarditis is defined by the time course and severity of illness. Acute myocarditis is the presence of an acute cardiomyopathy with myocardial inflammation. Meanwhile, chronic myocarditis is subdivided into two entities: chronic active myocarditis and chronic persistent myocarditis. The chapter also considers fulminant myocarditis, cardiac sarcoidosis, and idiopathic giant cell myocarditis (GCM).