Does temporary mechanical circulatory support with Impella 5.5 induce de novo human leukocyte antigen antibodies production in heart transplantation candidates?

Background: Little is known about de novo human luekocyte antigen (HLA) antibody development with Impella 5.5 temporary mechanical circulatory assist support and downstream effects following heart transplantation in the new heart allocation system. Methods: Thirteen Impella and 17 control patients without device support were prospectively enrolled between December 2020 and June 2022. HLA antibodies with calculated panel reactive antibodies (cPRA) were assessed pre and postdevice implantation and within 1-year postheart transplantation. Results: Baseline prevalence of HLA antibodies and median cPRA were similar between groups. Patients in the study arm were on Impella support for a median of 7 days. No significant differences in HLA antibodies were observed postdevice or postheart transplant. One patient in the Impella arm developed rejection and required treatment. One Impella patient died due to infection and 1 control patient died due to primary graft dysfunction. Conclusions: Short-term use of Impella 5.5 in the new heart allocation system does not appear to increase risk of de novo HLA antibody development. Further studies are needed to validate these preliminary findings.