Idiopathic Dilated Cardiomyopathy as a Late Complication of Healed Viral (Coxsackie B virus) Myocarditis: Historical Analysis, Review of the Lliterature, and a Postulated Unifying Hypothesis

A historically based literature review of the relationship between acute viral myocarditis and the subsequent development of a dilated cardiomyopathic state is presented. A strong emphasis on a state of definitional ambiguity in the literature as regards the timing of the myopathic state following a viral infection is noted, i.e. does the myopathic state develop acutely and concomitantly with viral myocarditis due to overwhelming viral mediated myocardial cell necrosis, subacutely due to negative remodeling following severe but not overwhelming viral mediated myocardial cell necrosis, subacutely due to a sustained immune mediated myocarditis or in a delayed time frame following complete recovery from the initial infection (i.e. a return of normal histology and the absence of any cellular infiltrate and the presence of normal cardiac function). Evidence for the first two mechanisms is supported by the literature; evidence for the immune mediated chronic myocarditis remains controversial while hard evidence for the development of an idiopathic dilated cardiomyopathy (IDCM) as a late downstream complication following complete recovery from a bout of myocarditis is nonexistent. Recent basic virologic studies of myocarditis and the potential effects of retained noninfectious viral genomic material within the myocardium are reviewed. These studies allow for the proposal of a hypothetical mechanism whereby IDCM develops as a downstream complication of acute viral myocarditis.