Background: AlloMap® gene expression testing is a non-invasive screening tool approved for use in heart transplant recipients age 15 and older. Experience with AlloMap® in pediatric heart transplant recipients is limited. We sought to describe the variations in AlloMap® scores seen in pediatric heart transplant recipients.
Methods and Findings: This is a retrospective study of all pediatric heart transplant recipients with AlloMap® scoring at a single institution between 2013 and 2014. All possible scores were recorded. Other variables recorded at the time of each AlloMap® score included immunosuppressive regimen, patient demographics and endomyocardial biopsy (EMB) results. Patients were excluded if they had undergone other solid or multi-solid organ transplantation. Onehundred AlloMap® scores were available from 42 patients, with a median age at transplantation of 4.3 years. The median AlloMap® score for all patients was 32 (IQR, 30-35). Of the 100 AlloMap® scores, 10% were collected in patients <2 years, 41% in 2-12 years and 49% were >12 years of age. There was little difference in the median score between age groups (p=0.143). Forty-five scores had a concomitant biopsy. Twenty-eight (62%) patients had ISHLT grade 0 and 16 (36%) had ISHLT grade 1 rejection. AlloMap® scores were higher in patients with evidence of ISHLT grade 1 acute cellular rejection (ACR) on EMB (p=0.044). AlloMap® scores were similar across all immunosuppression regimens (p=0.403), with TAC+MMF (n=43) and TAC+SIR (n=27) being the most commonly used regimens. In patients with multiple AlloMap® readings, the median change in AlloMap® score from baseline reading was 2 (IQR, 2-5) without significant change on biopsy findings.
Conclusions: In pediatric heart transplant recipients, AlloMap® scores were higher in patients with ISHLT grade 1 rejection than in patients with ISHLT grade 0 rejection. AlloMap® scores did not appear to be affected by patient age or immunosuppression regimen. Further studies should be performed to confirm the findings of this study and determine the place for AlloMap® in post-transplant monitoring of pediatric patients.
Courtney Sutton, Ryan Butts, Ali Burnette, Andrew Savage, Walter Uber and A Lauren Haney
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