Myocarditis

Abstract

Many investigators favor the hypothesis that idiopathic dilated cardiomyopathy most often results from an acute viral myocarditis, either directly caused by persistent cardiac viral infection or secondary to an autoimmune response triggered by an antecedent exposure to virus. The development of in situ hybridization techniques allows direct demonstration of enterovirus-specific RNA sequences within the myocardium of patients with myocarditis and idiopathic dilated cardiomyopathy. Controversy now centers on the specificity of these findings, because more sensitive polymerase chain reaction amplification techniques have also found enterovirus nucleic acid sequences in a wide variety of cardiac tissues, including normal heart. Whatever the trigger mechanisms, elucidating the basic immunopathogenesis of ongoing myocardial injury in myocarditis and idiopathic dilated cardiomyopathy will likely have a significant impact on the development of novel therapies for immune-mediated heart disease.