PULM1: Outcomes of Recipients Aged 65 Years and Older Bridged to Lung Transplant with Extracorporeal Membrane Oxygenation (ECMO)

Abstract

Background: Extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplant (BTT) has been used to support critically ill patients on the waitlist with excellent outcomes post-transplant. Some centers cite candidate age ≥65 years as a contraindication despite minimal data to support restricting ECMO BTT among older candidates. We compared outcomes of ECMO BTT, mechanical ventilation (MV)-only BTT, and no BTT in recipients ≥65 years. Methods: For our waitlist analysis, lung transplant candidates ≥65 years with known ECMO cannulation dates 2005-2020 in the United Network for Organ Sharing (UNOS) database were included. Waitlist outcomes within one year of either listing or ECMO cannulation, whichever occurred first, were assessed. For the post-transplant analysis, lung-only recipients ≥65 years were included and stratified into ECMO BTT, MV-only BTT, or no BTT. Cox regression was used to assess 1- and 3-year mortality post-transplant. Multivariable models adjusted for baseline characteristics with p<0.1 on univariate analysis. Results: Of the 171 waitlist candidates ≥65 years with known ECMO implant dates, 96 (56.1%) were transplanted and 72 (42.1%) deteriorated/died within one year of listing or ECMO cannulation. Those who deteriorated/died spent more waitlist days on ECMO support compared to candidates who were transplanted (11 [5-17] vs. 4 [2-12] days, p<0.001). Of recipients ≥65 years, 135 (1.6%) received ECMO BTT, 219 (2.6%) received MV-only BTT, and 8,074 (95.7%) received no BTT. ECMO BTT recipients had higher LAS at transplant (86 [84-88] ECMO vs. 73 [41-88] MV-only vs. 39 [34-49] no BTT, p<0.001), spent fewer days on the waitlist (12 [5-34] ECMO vs. 18 [6-76] MV-only vs. 47 [14-141] no BTT, p<0.001), and were more likely to have restrictive disease pathology (92.6% ECMO vs. 67.1% MV-only vs. 66.3% no BTT, p<0.001; Table 1). At 72 hours post-transplant, ECMO BTT recipients were more likely to remain intubated than those who received no BTT (70.6% ECMO vs. 71.2% MV-only vs. 22.6% no BTT, p<0.001) and more likely to be on ECMO than those who received either MV-only or no BTT (30.4% ECMO vs. 8.2% MV-only vs. 4.3% no BTT, p<0.001). ECMO BTT recipients had lower likelihood of pre-discharge acute rejection (3.0% ECMO vs. 10.5% MV-only vs. 6.9% no BTT, p=0.02). On multivariable analysis, ECMO vs. MV-only BTT was associated with increased mortality risk at 1 year (aHR[95% CI] 2.11[1.33-3.35]) and 3 years (aHR 1.51[1.07-2.12], Figure 1) post-transplant. Conclusion: We found that ECMO BTT in candidates ≥65 years is associated with inferior post-transplant outcomes compared to MV-only or no BTT, even after adjusting for donor and recipient characteristics. However, despite being sicker at transplant, more than half of recipients ≥65 years receiving ECMO BTT were alive at 3 years post-transplant, furthering our understanding of whether ECMO BTT is a reasonable choice in older candidates. Table 1. Baseline characteristics of lung transplant recipients ≥65 years of age from 2005 to 2020 in the United Network for Organ Sharing registry, by bridging strategy.Figure 1. (A) Unadjusted and (B) adjusted 3-year survival of lung transplant recipients ≥65 years of age from 2005 to 2020 in the United Network for Organ Sharing registry, by bridging strategy. Hazard ratios represent extracorporeal membrane oxygenation (ECMO) bridge-to-transplant (BTT) versus mechanical ventilation (MV)-only BTT.