HHV-6 infection has been reported to cause cardiac complications in both the immunocompromised and the immunocompetent, including myocarditis (Ashrafpoor 2013, Leveque 2011, Mahrholdt 2006), dilated cardiomyopathy (Tatrai 2011), sinus tachycardia (Nishimoto 2012), and “idiopathic” left ventricle dysfunction (Kühl 2005). Furthermore, in 2013 a child with drug-resistant HHV-6B myocarditis was successfully treated with Artesunate, an antimalarial medication known to have efficacy against HHV-6 (Hakacova 2013). Despite increasing reports of HHV-6 myocarditis among immunocompromised patients, however, the virus’s role in the pathology of acute chronic myocarditis remains poorly defined.

A group of physicians from the University Hospital in Reims, France, have reported a case of fatal HHV-6 myocarditis in an immunocompetent patient (Leveque 2011). Although the initial bloodwork and heart biopsies tested came back negative for the presence of HHV-6 infection, post-mortem frozen tissues showed evidence of chronic HHV-6 infection in regions of the heart that had not been biopsied in the initial screening process. This report demonstrates that HHV-6 can establish a nearly undetectable chronic active myocarditis in the immunocompetent which may eventually result in heart failure and death. The authors emphasize the importance of endomyocardial biopsy and molecular analysis on frozen tissue—as opposed to fixed tissues—as HHV-6 was not detected in either serum or in paraffin fixed tissues of this patient. The antibody titers for HHV-6 were not elevated. Endomyocardial biopsies are not performed for most myocarditis cases in the United States, but are done routinely in Germany and in other European centers.

In addition to the direct association with myocarditis, HHV-6 is also associated with heart complications due to endothelial cell dysfunction. For more information, visit our page on HHV-6 & Endothelial Cell Dysfunction/Arteriopathies.