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.

This is a retrospective study of all pediatric heart transplant recipients at a single institution between 2010 and 2014. All possible Allomap® scores were recorded. Other variables recorded at the time of each Allomap® score included immunosuppressive regimen, patient demographics and endomyocardial biopsy results (EMB). Patients were excluded if they had undergone other solid or multi-solid organ transplantation.

There were 100 Allomap® scores in 42 patients. The median Allomap® score for all patients was 32 (IQR, 30-35). The median time from transplantation to Allomap® score was 1569 days (IQR 268-3597). 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 [<2 years: 34(IQR, 33-36), 2-12 years: 33 (IQR, 30-35), >12 years: 32 (IQR, 29-35), p=0.143]. Forty-five scores had a concomitant biopsy. Per biopsy, 28 (62%) patients had ISHLT grade 0 and 16 (36%) had ISHLT grade 1 rejection. Allomap® scores were higher in patients with evidence of acute cellular rejection (ACR) on EMB (grade 0: median 32, IQR 29-35 v. grade 1: median 35, IQR 32-36,p=0.044). Allomap® scores were similar across all immunosuppression regimens (p=0.403), with TAC+MMF (n=43, median score 33) and TAC+SIR (n=27, median score 31) being the most commonly used regimens. In patients with multiple Allomap® readings (n=28), the median change in Allomap® score from baseline reading was 2 (IQR, 2-5).

In pediatric heart transplant recipients with biopsy evidence of ACR, the corresponding Allomap® scores were higher than in patients without ACR. Allomap® scores did not appear to be affected by patient age or immunosuppression regimen. Further studies should be performed to confirm the lack of association with age and immunosuppressive regimen as well as to determine if greater variability in Allomap® scores are associated with worse outcomes in pediatric heart transplant recipients.

« Back to 2015 American Transplant Congress