Impact of Duration of Veno-Arterial Extra-Corporeal Membrane Oxygenation Cannulation on Post Transplant Survival Following the UNOS Allocation Policy Change

Abstract

Purpose The 2018 revised UNOS heart allocation policy restructured the prioritization of patients awaiting heart transplantation (HT) based on illness severity. Among the group of patients assigned the highest priority includes candidates cannulated with veno-arterial extracorporeal membrane oxygenation (VA ECMO). Those meeting strict hemodynamic criteria set forth by UNOS are granted a 7-day status 1 window. Beyond this timeframe, transplant programs must apply for extensions with hemodynamic data demonstrating continued dependence on VA-ECMO support and contraindications to a durable device. Herein we report the 6-month survival outcomes for patients bridged to transplant with VA-ECMO based on duration of VA-ECMO support prior to HT. Methods The UNOS registry was queried for all patients on VA-ECMO in the 12-months following the UNOS allocation policy change. A total of 122 patients were bridged to HT with VA-ECMO in this time. Patients were divided into short- (N=105) and long- (N=17) duration groups based on time on VA-ECMO support, while listed as Status 1, using a cutoff of 7-days. Clinical, laboratory, hemodynamic, and ischemic time were compared with standard statistical methods and predictors of post-transplant mortality were assessed with Cox proportional hazards modeling. Results Baseline recipient characteristics and comorbidities were similar between the short- and long-duration groups. Median number (interquartile range) of days on VA-ECMO while listed as status 1 was 3 (2, 4) days versus 9 (7, 13) days with 105/122 (86%) successfully bridged to HT in less than 7-days. The short-duration group spent a total median time on VA-ECMO support of 4 (2, 9) days compared to 24 (17, 50) days in the long-duration group. There were no significant differences in invasive cardiac hemodynamics, serum creatinine, mechanical ventilation or need for dialysis at time of transplantation. Additionally, there were no differences in mean donor age or allograft ischemic times. Finally, there were no significant differences in 6-month post-HT survival outcomes between the two groups (log-rank, p\u202f=\u202f0.91). Conclusion Post-transplant survival did not depend on duration of VA-ECMO cannulation based on a cutoff of 7-days. This finding suggests that longer duration of VA-ECMO support may still permit acceptable outcomes.