A fatal case of Human Herpesvirus 6 chronic myocarditis in an immunocompetent adult.

Background: Human Herpesvirus 6 (HHV-6) is an important cause of fulminant or acute viral myocarditis in immunocompromised or immunocompetent patients. However the physiopathological mechanisms of HHV-6 related acute myocarditis and the involvement of subsequent HHV-6 reactivation phases in the development of chronic cardiomyopathies remain to be assessed.

Objectives: To describe a case of fatal HHV-6 chronic myocarditis in an immunocompetent adult.

Study Design: Case report and detailed histological and viral diagnoses by combination of histology/immunohistochemistry and polymerase chain reaction techniques on cardiac tissues.

Results: Histopathological analysis of ventricular tissues showed large interstitial and scarring fibrotic areas with a moderate mononuclear cell infiltrate compatible with histological aspect of chronic myocarditis. Detection of both HHV-6 by real-time PCR and viral glycoproteins in mononuclear and endothelial cells by immunohistochemistry evidenced an ongoing cardiac HHV-6 replication with viral late protein synthesis activity.

Conclusions: This case report indicates that HHV-6 can establish a chronic active myocarditis leading to heart failure in immunocompetent subjects.