Clinical findings in acute viral myocarditis. With special attention to experimental and immunological evidence.

According to analysis of 40,000 autopsies, the incidence of myocarditis is approximately 3.5%, the diagnosis of which had not been established in the majority prior to death. The clinical characteristics of myocarditis encompass a wide spectrum from an asymptomatic course to sudden cardiac death. Symptoms and findings of congestive heart failure or an inflammatory virus disease may be present. There is usually evidence of nonspecific clinical, radiologic, electrocardiographic, echocardiographic and blood chemistry abnormalities. In the presence of myocarditis, gallium scintigrams are generally pathologic. Virologic and serologic studies may have an important, albeit not decisive, role in establishing the diagnosis. In the acute phase, endomyocardial biopsy can document inflammatory changes. For the most part, treatment is symptomatic. Ventricular arrhythmias and high-grade conduction disturbances prerequisite vigilant monitoring as well as adequate medical and, if indicated, electrical therapy. In addition to conventional treatment, steroids, more recently, in combination with azathioprine, have been employed in patients with subacute and chronic myocarditis. The course of myocarditis is frequently benign although, in some cases, congestive heart failure may develop. Laboratory studies in DBA/2 mice with congestive heart failure subsequent to surviving myocarditis have shown myocardial fibrosis and hypertrophy without mononuclear cell infiltrates indicative of transition to dilated cardiomyopathy.