Impact of donor blood type on outcomes after prolonged allograft ischemic times

Objective: The study objective was to determine the influence of allograft ischemic time on heart transplant outcomes among ABO donor organ types given limited prior reports of its survival impact.

Methods: We identified 32,454 heart transplants (2000-2016) from the United Network for Organ Sharing database. Continuous and categoric variables were analyzed by parametric and nonparametric testing. Survival was determined using log-rank or Cox regression tests. Propensity matching adjusted for preoperative variables.

Results: By comparing allograft ischemic time less than 4 hours (n = 6579) with 4 hours or more (n = 25,875), the hazard ratios for death at 15 years after prolonged ischemic time (≥4 hours) for blood types O, A, B, and AB were 1.106 (P < .001), 1.062 (P < .001), 1.059 (P = .062), and 1.114 (P = .221), respectively. Unadjusted data demonstrated higher mortality for transplantation of O versus non-O donor hearts for ischemic time 4 hours or more (hazard ratio, 1.164; P < .001). After propensity matching, O donor hearts continued to have worse survival if preserved for 4 hours or more (hazard ratio, 1.137, P = .008), but not if ischemic time was less than 4 hours (hazard ratio, 1.042, P = .113). In a matched group with 4 hours or more of ischemic time, patients receiving O donor organs were more likely to experience death from primary graft dysfunction (2.5% vs 1.7%, P = .052) and chronic allograft rejection (1.9% vs 1.1%, P = .021). No difference in death from primary graft dysfunction or chronic allograft rejection was seen with less than 4 hours of ischemic time (P > .150).

Conclusions: Compared with non-O donor hearts, transplantation with O donor hearts with ischemic time 4 hours or more leads to worse survival, with higher rates of primary graft dysfunction and chronic rejection. Caution should be practiced when considering donor hearts with the O blood type when anticipating extended cold ischemic times.