(654) Personalizing Cytomegalovirus Prophylaxis in the First Year after Pediatric Heart Transplantation: Impact of a CMV Cell Mediated Immunity-Based Approach

PurposeImmune monitoring of cytomegalovirus (CMV) specific cell-mediated immunity (CMI) in transplant recipients has the potential to decrease morbidity and mortality related to CMV disease. In May 2020, our institution adopted the use of CMV CMI testing to guide extension of CMV prophylaxis (PPX) beyond six months following pediatric heart transplantation (PHT) in vulnerable recipients. Our aim was to compare the incidence of cytomegalovirus DNAemia, CMV disease, and allograft rejection in the first year following PHT before (Cohort 1) and after (Cohort 2) incorporation of a CMV cell mediated immunity (CMI)-based extended prophylaxis protocol for CMV intermediate (IR) and high (HR) risk PHT recipients at a single center.MethodsAll PHT recipients transplanted from May 2018 to October 2021 with a minimum of one year post-transplant follow-up were included. Rates of CMV disease, CMV DNAemia, and episodes of allograft rejection during the first year post-transplant were compared between cohorts.ResultsBaseline CMV risk classification was similar between cohorts (Table). Among IR/HR PHT recipients, 11% (2/18) of patients in Cohort 1 developed CMV disease following CMV PPX; in contrast, no CMV disease (0/25) was noted among patients in whom CMV CMI testing was used to guide CMV PPX (Cohort 2).ConclusionBy selectively targeting extended prophylaxis, transition to a CMV CMI-based prophylaxis protocol may help reduce CMV disease in the first year after pediatric heart transplant compared to time-based protocols. Given the relatively low incidence of CMV disease in this population, larger multi-institutional studies will be needed to establish efficacy. Immune monitoring of cytomegalovirus (CMV) specific cell-mediated immunity (CMI) in transplant recipients has the potential to decrease morbidity and mortality related to CMV disease. In May 2020, our institution adopted the use of CMV CMI testing to guide extension of CMV prophylaxis (PPX) beyond six months following pediatric heart transplantation (PHT) in vulnerable recipients. Our aim was to compare the incidence of cytomegalovirus DNAemia, CMV disease, and allograft rejection in the first year following PHT before (Cohort 1) and after (Cohort 2) incorporation of a CMV cell mediated immunity (CMI)-based extended prophylaxis protocol for CMV intermediate (IR) and high (HR) risk PHT recipients at a single center. All PHT recipients transplanted from May 2018 to October 2021 with a minimum of one year post-transplant follow-up were included. Rates of CMV disease, CMV DNAemia, and episodes of allograft rejection during the first year post-transplant were compared between cohorts. Baseline CMV risk classification was similar between cohorts (Table). Among IR/HR PHT recipients, 11% (2/18) of patients in Cohort 1 developed CMV disease following CMV PPX; in contrast, no CMV disease (0/25) was noted among patients in whom CMV CMI testing was used to guide CMV PPX (Cohort 2). By selectively targeting extended prophylaxis, transition to a CMV CMI-based prophylaxis protocol may help reduce CMV disease in the first year after pediatric heart transplant compared to time-based protocols. Given the relatively low incidence of CMV disease in this population, larger multi-institutional studies will be needed to establish efficacy.