Does cytomegalovirus serology impact outcome after pediatric heart transplantation?

Background: Cytomegalovirus (CMV) infection has been implicated in a number of complications after heart transplantation. A recent study suggested that children with positive CMV serology (CMV(+)) before transplantation are at increased risk of developing coronary allograft vasculopathy (CAV) and death when compared with CMV(-) recipients. We analyzed data from the Pediatric Heart Transplant Study Group to determine the impact of recipient CMV status and CMV mismatching on outcome. In addition, the use and efficacy of CMV prophylaxis were studied.

Methods: Subjects <18 years of age who underwent heart transplantation during the period from 1993 to 2007 were analyzed. Those transplants in which either the recipient or donor were <6 months of age were excluded due to the confounding effects of maternal antibody. The primary outcome variable was freedom from CAV (mild or greater). Secondary outcomes included freedom from death and freedom from clinical CMV infection. Risk factors were assessed using parametric hazard regression.

Results: Of the 1,598 subjects included in the analysis, 637 (40%) were CMV(+) at the time of transplantation. Some form of CMV prophylaxis was administered to 67% of all recipients, most commonly with a CMV mismatch (donor CMV(+)/recipient CMV(-)). Freedom from clinical CMV infection at 5 years was 91%. Pre-transplant CMV serology was not associated with mortality (p = 0.40) or risk of developing CAV (p = 0.10). CMV mismatch was associated with increased risk of clinical CMV disease (p < 0.001). The use of CMV prophylaxis had no association with mortality or development of CAV. There was also no significant association between CMV prophylaxis and the development of clinical CMV infection.

Conclusions: CMV(+) serology at time of pediatric heart transplantation had no demonstrable association with death or development of CAV. CMV(-) recipients who receive a CMV(+) organ are at increased risk of clinical CMV disease. CMV prophylaxis was commonly used, although further studies are needed to establish an optimal approach for prevention of CMV disease in this population.