A group of physicians from the University Hospital in Reims, France, have reported a case of fatal HHV-6 myocarditis in an immunocompetent patient. 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, and in the absence of diagnosis and treatment, 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, who died of an HHV-6 infection. The antibody titers for HHV-6 were not elevated. Endomyocardial biopsies are not performed for most myocarditis cases in the United States, although they are done routinely in many European countries.
HHV-6 infection has been reported to cause cardiac complications in both the immunocompromised and the immunocompetent, including myocarditis (Mahrholdt 2006) dilated cardiomyopathy (Comar 2009) and “idiopathic” left ventricle dysfunction (Kühl 2005). Despite a recent increase in publications that report HHV-6 myocarditis in immunocompromised patients, however, the virus’s role in the pathology of acute chronic myocarditis remains poorly defined.
Uwe Kühl, who leads a large cardiology practice at Charite-University in Berlin, treats HHV-6 positive myocarditis with valganciclovir and has achieved considerable success. His associate Dirk Lassner reported on these results at the 2011 International Conference on HHV-6 & 7. View video.