The role of viral infections in the development of dilated cardiomyopathy.

Enteroviruses (EVs) are the most frequent pathogens in myocarditis and in the subsequently developing dilated cardiomyopathy as well. Furthermore, persistence of other viruses might play a pathogenic role in the evolution from myocarditis to dilated cardiomyopathy. Explanted heart of 28 patients, who underwent heart transplantation were screened for EV, AdV3 and HHV6 sequences in order to assess the incidence of cardiac viral infection that may be implicated in the pathogenesis of cardiomyopathy, and estimate viral distribution in the myocardium. Viral sequences were extracted from five different regions of the hearts. Nested PCR was used to amplify conservative regions of AdV3, HHV6 and EVs. Histological examination was performed on routinely processed myocardial samples. AdV3 was verified in one fourth of the patients. ADV3 and HHV6 sequences coexisted in one case with inflammatory cardiomyopathy. Some patients had more than one positive area of their heart. AdV3 positive right ventricular samples were double in amount compared to the left ones. None of the patients had positive result for EV. This is the first occasion to identify AdV3 (a mainly respiratory infective virus) sequence in explanted hearts of cardiomyopathy patients. Though the clinical importance of our results is still unclear, AdV3 could be a new member of the viral group with possible pathogenic effect on the myocardium. Regional distribution of viral sequence location confirmed that the right ventricular wall as a biopsy sampling site might be adequate for endomyocardial biopsy pro diagnostic purposes.