Acute
myocarditis is one of the most challenging diseases to diagnose and treat in cardiology. The true incidence of the disease is unknown.
Viral infection is the most common etiology. Modern techniques have improved the ability to diagnose specific viral pathogens in the myocardium. Currently, parvovirus B19 and adenoviruses are most frequently identified in endomyocardial biopsies. Most patients will recover without sequelae, but a subset of patients will progress to chronic inflammatory and
dilated cardiomyopathy. The pathogenesis includes direct viral myocardial damage as well as autoimmune reaction against cardiac
epitopes. The clinical manifestations of acute
myocarditis vary widely--from asymptomatic changes on electrocardiogram to fulminant
heart failure, arrhythmias and
sudden cardiac death. Magnetic resonance imaging is emerging as an important tool for the diagnosis and follow-up of patients, and for guidance of endomyocardial biopsy. In the setting of acute
myocarditis endomyocardial biopsy is required for the evaluation of patients with a clinical scenario suggestive of giant cell
myocarditis and of those who deteriorate despite supportive treatment. Treatment of acute
myocarditis is still mainly supportive, except for giant cell
myocarditis where
immunotherapy has been shown to improve survival.
Immunotherapy and specific
antiviral treatment have yet to demonstrate definitive clinical efficacy in ongoing clinical trials. This review will focus on the clinical manifestations, the diagnostic approach to the patient with clinically suspected acute
myocarditis, and an evidence-based treatment strategy for the acute and chronic form of the disease.