Objective: Recent clinical and echocardiographic studies have identified dilated cardiomyopathy in 10-20% of HIV-infected adults. The purpose of this study was to determine the role of cardiotropic cytomegalovirus (CMV) infection in the development of HIV-associated cardiomyopathy.
Design: We generated sense and antisense digoxigenin-labeled riboprobes derived from the CMV immediate-early (IE) and delayed-early (DE) genes and applied them retrospectively to endomyocardial biopsy samples and control autopsy cardiac samples from HIV-infected patients.
Setting: Tertiary care, referral hospital.
Patients: Twelve consecutive HIV-infected patients with global left ventricular hypokinesis demonstrated on two-dimensional echocardiography; eight randomly selected control autopsy cardiac samples from HIV-infected patients without cardiac disease during life.
Measurements and main results: Of the 12 endomyocardial biopsy specimens, six (50%) were found to have specific myocyte nuclear and perinuclear hybridization for transcripts of the CMV IE gene, consistent with non-permissive or latent infection. Similar patterns were not found in any of the eight autopsy control samples. All six patients presented with unexplained congestive heart failure and had CD4 counts less than 100 x 10(6)/l; all six biopsy samples had immunohistochemical evidence of increased myocardial major histocompatibility complex (MHC) class I expression, a finding typical of non-HIV myocarditis. None of the endomyocardial biopsy samples had characteristic CMV inclusions and no specific hybridization was noted with the DE gene riboprobe, suggesting that no active viral DNA replication was present. Only two of the six patients with myocyte hybridization with the IE riboprobe had clinical evidence of solid organ infection with CMV at the time of cardiovascular presentation.
Conclusions: This study is the first to demonstrate the expression of the IE gene of CMV within myocytes from HIV-infected patients with cardiomyopathy, suggesting a non-permissive infection of myocytes without classical intranuclear inclusions. Myocyte infection may be necessary to trigger cellular and humoral-mediated cardiac injury and may be best identified using in situ hybridization techniques.