ABO-Incompatible Heart Transplantation—Experience of a Single Center

Objectives: Children under 1 year have the highest mortality on the heart transplant waiting list (HTX). However, ~15% of donor organs under 2 years of age cannot be mediated in the absence of suitable recipients. In comparison to the ABO-compatible (ABOc), the ABO-incompatible (ABOi) HTX is a possibility to mediate as many donor organs as possible.

Methods: Between June 2012 and February 2018, 23 patients under 2 years were transplanted at our Pediatric Heart Center (ABOi n = 8; ABOc n = 15). Both groups were compared retrospectively (pre-, intra-, postoperative, and follow-up). The treatment strategy was based on an internal protocol.

Results: The biometric data of both groups were comparable. Ventricular assist device therapy before HTX was more frequent in ABOi (ABOi 50% vs. 13% in ABOc); waiting time in ABOi significantly longer (ABOi median 71 days [3–339] vs. ABOc median 19 days [ 1–132]; p = 0.02). The ischemic time (ABOi 257 ± 65 minutes vs. ABOc 241 ± 56 minutes) and intensive care duration (ABOi mean 30 ± 27 days vs. ABOc 31 ± 12 days) were comparable. The frequency of graft rejection was 13%. CMV reactivation occurred comparably frequently (ABOi 25% vs. ABOc 26%). Bacteremia with antibiotic treatment tended to occur more frequently in ABOi (50% vs. 13% in ABOc). The immunosuppression of both groups was performed according to the same scheme. Within the first year, three patients died (ABOi n = 2; ABOc n = 1). Causes of death in ABOi were malignancy (n = 1) and multiorgan failure in mitochondriopathy (n = 1); in the ABOc patient sudden cardiac death. Malignancy occurred in each group once within the first year. The overall survival, rejection rate, graft function, and general susceptibility to infection (outpatient domestic infections) were higher in the group of ABOc patients (50% ABOi vs. 85% ABOc).

Conclusion: ABOi-HTX can be successfully performed in children < 2 years. Due to the small number of patients, there are no significant differences between the two groups except for longer waiting times on the list. It is to be discussed whether the allocation can be performed according to the principle of urgency and prospect of success at least in this age group independent of the blood group. It remains to be checked whether ABOi-HTX can also be successfully performed in patients > 2 years.