[Myocarditis and cardiomyopathy]

In situ hybridization studies have shown that myocardial enterovirus infections may be detected in acute and chronic enterovirus-induced myocarditis, indicating the possibility of myocardial enterovirus persistence in the human heart. As well, such infections can be observed in patients with dilated cardiomyopathy, a condition which may evolve from chronic myocarditis. The discovery of possible enterovirus persistence in the human heart is supported by the finding in different strains of immunocompetent mice, demonstrating that coxsackievirus B3, typically a cytolytic enterovirus, is capable of evading immunological surveillance in a host-dependent fashion, thus inducing a persistent type of heart muscle infection. Progress is currently being made in unraveling the molecular mechanisms of enterovirus persistence, the diversity of host and virus genetics and their impact on the nature and severity of myocardial injury. Apart from providing an etiologic diagnosis, there are therapeutic implications from in situ demonstration of myocardial enterovirus infection. Evaluation of specific antiviral agents, for example interferons, may lead to the development of new therapeutic strategies capable of providing protection against myocardial enterovirus infection.