Utilization of Mechanical Circulatory Support Devices and Impact on Outcomes in the New Heart Allocation System: An Analysis of the UNOS Registry

Abstract

In October 2018, a new heart transplantation (HT) allocation system was implemented with the intent of prioritizing the most medically urgent candidates, including those with cardiogenic shock requiring percutaneous support, extracorporeal membrane oxygenation (ECMO), and surgical support devices. We hypothesized that utilization of acute mechanical circulatory support (MCS) increased nationwide as a result of the new allocation system. The UNOS database were queried to identify patients listed for HT on or after January 2017. Patients were categorized into: 1) old allocation (listed and removed before 10/18/2018) and 2) new allocation (listed on or after 10/18/2018) groups. Patients who crossed over from old to new allocation were excluded from the analysis. MCS utilization and post-transplant graft survival were compared in the two eras. 4663 patients were waitlisted during the old allocation compared to 1759 waitlisted patients in the new allocation system. There was a significant increase in the utilization of intra-aortic balloon pump (IABP) (6.1% to 9.7%, p<0.001) at transplant listing in the new allocation system. ECMO and LVAD/RVAD/BiVAD/TAH use at listing were unchanged (Figure). At the time of HT, there was a significantly higher utilization of IABP (9.4% to 32.7%) and ECMO (1.2% to 7.7%) accompanied by a lower utilization of LVAD/RVAD/BiVAD/TAH (40.5% to 30.0%) (all p<0.05). Post-transplant graft survival at 90 days was significantly lower in the new allocation compared to old (94.6% vs 84.8%, log-rank p<0.001). 90-day post-transplant survival was highest in patients bridging with IABP, compared to ECMO and LVAD/RVAD/BiVAD/TAH (93.5%, 68.2%, 78.6%, log rank p=0.002) CONCLUSION: Use of acute circulatory support devices has increased as bridge to HT. Early post-transplant graft survival is significantly better for patients bridged with IABP support compared to ECMO or other surgical support devices.