A hematology group in Australia reported the first confirmed case of biopsy-proven HHV-6 myocarditis post-hematopoietic stem cell transplantation. The 62-year old patient had a relatively low HHV-6 DNA viral load (<200 copies/mL of plasma) three days before the patient passed away due to progressive biventricular failure on day +30. The post-mortem exam confirmed dilated cardiomyopathy and focal changes consistent with viral myocarditis. The cardiac tissue was positive for HHV-6 DNA by nested and quantitative PCR (1.4% of cells) and immunohistochemistry performed by Coppe Labs (USA) revealed HHV-6 antigen in cardiac myocytes.
Separately, a Japanese group reported a woman who developed pericarditis with over 10,000 copies of HHV-6 DNA per ml in the pericardial fluid, after receiving a cord blood transplant.
HHV-6 has been established as a causative agent of myocarditis and both acute and chronic heart failure in immunocompetent patients (Mahrholdt 2006, Kuhl 2005, and Ashrafpoor 2013). HHV-6 can cause a persistent organ infection with little trace in the blood (Buyse 2013). In a similar case of fatal myocarditis in an immunocompetent man, the HHV-6 was discovered only at autopsy (Leveque 2011).
Read the full case report on HHV-6 myocarditis:Brennan 2015
Read the case report on HHV-6 pericarditis: Yoshida 2015