Human herpes virus 6 in archival cardiac tissues from children with idiopathic dilated cardiomyopathy or congenital heart disease

Objective: To explore the possible role of human herpes virus 6 (HHV-6) in cardiac disorders in childhood in a retrospective study on archival specimens of explanted hearts. Methods: 16 children (median age at transplantation 11.0 years) with idiopathic dilated cardiomyopathy (DCM) and 19 children (median age at transplantation 1.0 year) with congenital heart disease (CHD), previously found to be negative for other cardiotropic viruses such as enteroviruses, adenovirus, parvovirus B19, cytomegalovirus and Epstein-Barr virus, were tested for HHV-6 by quantitative real-time PCR and by genotyping. In addition, HHV-7/8 infection was investigated by qualitative PCR. Results: HHV-6 B variant was detected in 11 of 35 samples (31.4%) with a mean viral load of 3.1 × 10² copies/u.g of DNA. When assessed by heart disorder, the prevalence was different in the two groups (43.7% in DCM and 21% in CHD) while the mean viral loads were similar. In a logistic multivariate analysis HHV-6 was independently associated with DCM, taking CHD as reference and adjusting for age (best estimate: OR = 6.94; 95% CI 1.00 to 49.85; p = 0.05). Conclusions: Although the clinical significance of the results is unknown, HHV-6 B genome is frequently detected in explanted hearts from children with DCM and to a lesser extent with CHD, thus adding evidence for HHV-6 cardiac involvement.