A group from Italy has detected an unusually high rate of active HHV-6 infection among hospital patients with cardiac disease. The group reports 18.6% (13/70) of subjects with cardiac disease had detectable HHV-6 viremia, a number markedly elevated above the only 2% of healthy subjects found to have viremia using the same assay. HHV-8 viremia, on the contrary, was not detected in any patient samples.
While the group did not find coronary instability particularly associated with active HHV-6, the findings are intriguing and may point to an increased risk of HHV-6 reactivation among adult patients under particular conditions of stress such as hospital admission due to cardiac disease. Previous reports indicate that the detection of HHV-6 increases dramatically among several related groups of patients, including those admitted to medical or surgical intensive care units regardless of previous etiology (Razonable 2002). In addition, the group indicates that the possibility that the cardiac patients in this study may also be “independently at an increased risk of HHV-6 reactivation, possibly due to endothelial damage or stress secondary to coronary disease or cardiac valvular disease.”
The mean viral load measured among cardiac patients in this cohort was low (104 copies/mL plasma), affirming previous reports that indicate a difficulty to ascertain the extent of low-level active HHV-6 infection in patients with cardiac conditions without biopsy or use of a highly sensitive assay. As studies continue to show that HHV-6 is a significant cause of heart complications such as myocarditis, physicians must begin to use more elaborate techniques to identify patients who may benefit from anti-HHV-6 therapy in this setting.