The Natural History of Pre-Existing Donor Specific Antibody and Amnestic Responses after Heart Transplantation

Purpose Sensitized patients have prolonged wait times for heart transplant and often low-level donor specific antibodies (DSA) will be crossed when accepting a donor heart. The purpose of this study was to determine if positive low-level DSA at the time of transplant increase in strength post transplant and increase the risk of antibody mediated rejection (AMR). Methods We reviewed 72 heart transplant patients between 2010 and 2018 in whom low-level DSA were crossed. DSA strength, as measured by mean fluorescence intensity (MFI) and AMR on biopsy was assessed at 1, 3, 6, 12 months post transplant. Other outcomes assessed: freedom from first-year rejection (acute cellular rejection (ACR), any treated rejection (ATR)), freedom from cardiac allograft vasculopathy (CAV, as defined by stenosis ≥30% by angiography), and freedom from graft dysfunction (LVEF ≤40%). Patients were compared to a contemporaneous control group conditional to 1-year survival without DSA at transplant. Results Approximately one-third of patients with pre-existing DSA at transplant demonstrated an increase in DSA strength. Patients with pre-existing DSA had decreased freedom from ATR and AMR but no differences in freedom from CAV, graft dysfunction, or ACR compared to the control group. Conclusion Crossing low-level DSA may increase the risk of AMR, but there is no difference in clinically important sequelae such as CAV or graft dysfunction. Thus, accepting low-level DSA at the time of transplant appears feasible and could broaden the donor pool.