Suboptimal Six Minute Walk Distance Does Not Impact Survival in Lung Transplant Recipients Bridged with Extracorporeal Support

Abstract

<h3>Purpose</h3> Preoperative six-minute walk distance (6MWD) is associated with survival following lung transplantation; however, its predictive value remains unclear for patients on extracorporeal support (ECMO). Our study aimed to assess the impact of ECMO utilization on posttransplant survival among patients with suboptimal 6MWD. <h3>Methods</h3> Using data from the United Network for Organ Sharing, we included adult, first-time lung transplant recipients between May 3, 2005 and March 20, 2020 with suboptimal 6MWD (< 1200 feet). All patients on ECMO at listing who subsequently underwent 6MWD testing within 30 days were included in our ECMO cohort. Mechanically ventilated patients at listing were excluded. We then compared posttransplant survival based on ECMO status via Kaplan-Meier analysis. Descriptive analyses of the cohorts were done via Wilcoxon rank-sum tests for continuous variables and chi-square tests for categorical variables. <h3>Results</h3> Our overall study population included 21,266 patients: 60 in the ECMO cohort and 21,206 in the non-ECMO cohort. Both cohorts were predominantly male (57% in ECMO cohort vs. 58%, p = 0.972). In the ECMO cohort, the median age was lower (49 years, IQR 34-56 vs. 60 years, IQR 53-65; p < 0.0001); a greater percentage of patients underwent bilateral transplant (92% in ECMO cohort vs. 69%; p < 0.0001); and median 6MWD was lower (0, range 0-720 in ECMO cohort vs. 700, range 0-1199; p < 0.0001). Within the ECMO cohort, no difference in 3-year survival was observed between ambulatory (6MWD > 0) and non-ambulatory (6MWD = 0) patients (log rank, p = 0.536). Overall, no survival difference by ECMO status at 3 years was observed (log rank, p=0.718; Figure 1). <h3>Conclusion</h3> Our results suggest that ECMO, in appropriately selected patients, does not significantly impact postoperative survival compared to a population with similar suboptimal pretransplant functional status. Furthermore, no minimum distance was observed that conferred better or worse outcomes.