Several lines of evidence suggest the involvement of infectious agents in the pathogenesis of atherosclerosis. Furthermore, a correlation between infection-driven inflammatory burden and acute manifestation of coronary artery disease has been hypothesized. The aim of this work was to assess whether human herpesvirus (HHV)-6 and HHV-8, two DNA viruses with a distinct tropism for endothelium and lymphocytes, may be associated with coronary instability. An age- and gender-matched cross-sectional study was undertaken in 70 patients with testing of plasma HHV-6 and HHV-8 DNA load in different cardiovascular clinical settings: 29 patients with acute myocardial infarction, 21 patients with stable coronary artery disease, and 20 patients without coronary and carotid artery atherosclerosis subjected to cardiac valve replacement. In all patients, HHV-6 and HHV-8 plasma DNA was tested by using highly sensitive, calibrated quantitative real-time PCR assays which employ a synthetic DNA calibrator to adjust for DNA extraction and amplification efficiency. HHV-8 viremia was undetectable in all three groups. HHV-6 viremia was detected in a substantial fraction of the samples examined (18.6%) without significant differences among the three groups (ST segment elevation myocardial infarction: 17.2%; stable coronary artery disease: 14.3%; patients without coronary and carotid artery atherosclerosis: 25%). Furthermore, no significant differences in plasma HHV-6 load were observed amongst the three groups of patients. These findings indicate that coronary instability is not associated specifically with active HHV-6 or HHV-8 infection. However, an unusually high rate of active HHV-6 infection was documented among patients without atherosclerosis admitted to hospital with cardiac disease.
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