ABO Incompatible Heart Transplantation in Pediatric Recipients with High Isohemagglutinin Titers in the U.S.: A Multi-Institutional Analysis

Abstract

UNOS has liberalized the criteria for ABO incompatible (ABOi) heart transplant (HT) for patients less than two years of age. However, to date, the impact of high isohemagglutinin titers on graft survival has not been studied. Pediatric recipients (age <2) listed for heart transplantation in the UNOS database from 2008-2018 were reviewed. We compared graft survival between ABO-compatible (ABOc) and ABOi recipients and also between ABOi recipients transplanted with low (<;1:16) and high isohemagglutinin titers (>;1:16). Of 1687 HT performed in patients less than 2 years of age, 209 (13%) received ABOi transplants. (Figure 1) Majority of recipients listed for ABOi transplants had blood group O (67.5%). 18/209 (8.6%) recipients had high titers pre-transplant. Compared to ABOc recipients, ABOi recipients had similar distribution of age, gender, ethnicity, and were on similar cardiac support (inotropes, ventilator, ECMO, VAD) (p >; 0.05 for all). The wait-list times were also similar between both groups (64.2±50.8 vs 63.5±45.4 days, p >; 0.05). In patients less than 2 years, compared to ABOc transplants, ABOi transplants had similar 1-year (12.8 vs. 11%; P=0.39) and overall graft failure (21.1 vs. 19.9%; P=0.68). Compared to those with low-titers, patients transplanted with high isohemagglutinin titers, had similar 1-year (5.6% vs 12.6%; P=0.70) and overall graft failure (16.7% vs 18.2%; P=0.99) (Figure 1). Overall, utilization of ABOi transplantation is low in the relevant age group with most common recipients being blood group O. The use of ABOi transplant does not involve patient selection bias and has not affected the wait time. ABOi transplant recipients have graft survival similar to ABOc recipients. Most importantly, strength of anti-A or B titers do not impact graft survival in ABOi recipients.