Bridge to Transplant Outcomes with Axillary Intra-Aortic Balloon Pump versus Durable Left Ventricular Assist Device in the Current UNOS Heart Allocation System

Abstract

Purpose Since the 2018 UNOS Allocation system for heart transplantation change there has been concern for increased wait times for patients with durable left ventricular assist devices (LVAD) as bridge to transplantation (BTT). Furthermore, there are increasing trends to utilize axillary intra-aortic balloon pumps (Ax-IABP) to optimize cardiac unloading while maintaining ambulatory status in listed hospitalized patients. BTT outcomes data for Ax-IABP patients is limited. Understanding risks vs benefits of prolonged support with Ax-IABP vs LVAD in the current UNOS allocation environment is imperative. Methods We performed a single center retrospective review from October 18, 2017 to October 18, 2019 for all patients who underwent heart transplant. Waitlist times based on device (Ax-IABP or LVAD) to transplant were assessed in addition to time from transplant to discharge. Intraoperative cardiopulmonary bypass time, transfusion requirements and post-operative vasoactive support was also compared. Results 59 heart transplants occurred during our review period. 8 bridged with Ax-IABP (13%) and 22 with LVAD (37%). Average age in both groups was 53 with 75% and 68% males in the IABP and LVAD groups respectively. More LVAD as BTT were transplanted prior to the UNOS change (13 vs. 9). All Ax-IABP patients were transplanted after the UNOS change. Waitlist time for LVAD was higher than Ax-IABP patients (109d vs. 575d, p=0.0003). Waitlist time before and after UNOS change was not statistically different among LVAD patients, but did increase (497d vs 688d, p=0.176). Cardiopulmonary bypass time was longer in LVAD patients, but not significant, despite similar UNOS Status at transplant. More PRBC transfusions in the LVAD group (7.5u, IQR 0u - 24u) compared to the Ax-IABP group (2.6u, IQR 0u - 6u, p=0.0012). Time from transplant to discharge was 25 days for LVAD group and 13 for Ax-IABP group (p=0.075). Conclusion Waitlist time and transfusion requirements are statistically increased in LVAD as compared to Ax-IABP as BTT. In the current listing schema for heart transplant, risk vs. benefit of increased waiting time, perioperative hemodynamic compromise and increased transfusions in the LVAD population pose significant concerns. Further prospective studies with larger cohorts may be needed to better evaluate this trend.