Absence of viral nucleic acids in early and late dilated cardiomyopathy.

OBJECTIVE To investigate whether viral infection acts as a trigger factor for the development of dilated cardiomyopathy in genetically predisposed individuals with a family history of disease. SETTING Patients attending the cardiomyopathy unit in a cardiac tertiary referral centre. DESIGN Nested polymerase chain reaction (nPCR) was used to determine whether enteroviral, adenoviral, or cytomegaloviral nucleic acids were detectable in the myocardium of 19 asymptomatic relatives of patients with dilated cardiomyopathy; all these relatives had echocardiographic abnormalities thought to represent early disease. Explanted hearts from patients with end stage dilated cardiomyopathy were also studied and were compared with 25 controls (ischaemic heart disease (21), valvar heart disease (2), hypertrophic cardiomyopathy (1), restrictive cardiomyopathy (1)). Myocardial tissue from two fatal cases of culture positive coxsackie myocarditis was used as a positive control. RESULTS No viral nucleic acid was detected in any group other than in those with myocarditis. Spiking of random wells with purified recombinant viral nucleic acids confirmed the sensitivity and reproducibility of the assays. CONCLUSIONS Myocardial viral infection is not detectable in relatives of patients with dilated cardiomyopathy who are suspected of having early disease. There is no evidence that viruses act as a trigger factor for initiating the dilated cardiomyopathy in these patients.