Intraoperative Anti-A/B Immunoadsorption Is Associated With Significantly Reduced Blood Product Utilisation With Similar Outcomes in Paediatric ABO-Incompatible Heart Transplantation

Background: Intraoperative anti-A/B immunoadsorption (ABO-IA) was recently introduced for ABO-incompatible heart transplantation. Here we report the first case series of patients transplanted with ABO-IA, and compare outcomes with those undergoing plasma exchange facilitated ABO-incompatible heart transplantation (ABO-PE). Methods: Data were retrospectively analysed on all ABO-incompatible heart transplants undertaken at a single centre between 1st January 2000 and 1st June 2020. Data included all routine laboratory tests, demographics and pre-operative characteristics, intraoperative details and post-operative outcomes. Primary outcome measures were maximum post-transplant isohaemagglutinin titres, graft survival, occurrence of rejection and volume of blood product transfusions. Secondary outcome measures were length of intensive care and hospital stay. Demographic and survival data were also obtained for ABO-compatible transplants during the same time period for comparison. Results: Thirty-seven patients underwent ABO-incompatible heart transplants, with 27 (73%) using ABO-PE and 10 (27%) using ABO-IA. ABO-IA patients were significantly older than ABO-PE patients (p <0.001) and the total volume of blood products transfused during the hospital admission was significantly lower (164 [126 - 212] ml/kg vs. 323 [268 - 379] ml/kg, p <0.001). No significant differences were noted between methods in either pre or post-transplant maximum isohaemagglutinin titres, incidence of rejection, length of intensive care or total hospital stay. Survival comparison showed no significant difference between antibody reduction methods, or indeed ABO-compatible transplants (p = 0.47). Conclusions: This novel technique allows a significantly older population than typical to undergo ABO-incompatible heart transplantation, as well as significantly reducing blood product utilisation. Furthermore, intraoperative anti-A/B immunoadsorption does not demonstrate increased post-transplant isohaemagglutinin rebound or rates of rejection compared to ABO-PE. Survival is equivalent between ABO-IA, ABO-PE and ABO-compatible heart transplantation. Funding Statement: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: British Heart Foundation Research Fellowship to RI (FS/19/52/34563). Declaration of Interests: The authors declare no conflicts of interests. Ethics Approval Statement: Fulfilling the ethical guidelines of the Helsinki Declaration and approved by the Institutional Review Board as part of a wider study on Antibody Immunoadsorption for Transplantation (19HL02). Individual consent was not required since only routinely collected deidentified hospital data was evaluated within the secure digital research environment as part of an existing research database approval (17/LO/0008).