Abstract
Introduction: Extracorporeal membrane oxygenation (ECMO) has become increasingly common in patients with severe respiratory failure awaiting lung transplantation (LT). However, ECMO use in waitlisted patients is not without risks, and adds significant resource burden. This study examines the baseline characteristics of patients on ECMO who were waitlisted for lung transplantation, comparing outcomes between those who received a lung transplant versus those who were delisted or died on the waitlist. Methodology: The UNOS STAR file was queried for all waitlisted lung transplant candidates on ECMO from May 2005 to October 2023. We analyzed baseline characteristics and compared outcomes between those successfully transplanted and those who were delisted or died. Results: A total of 1,538 patients were waitlisted for lung transplant on ECMO during the study period; 1,016 patients received a lung transplant and 522 did not. Compared to transplanted candidates, delisted candidates were younger (median age 17 vs. 46 years, p=0.13), more likely female (49% vs. 38%, p<0.001), experienced significantly longer waitlist times (15 vs. 8 days, p<0.001), and had higher serum creatinine (0.70 vs. 0.62 mg/dL, p<0.001) and lower body mass index (BMI) at listing (24.3 vs. 25.7, p=0.004). Candidates with pulmonary vascular disease were more often delisted (17% vs. 6.1%, p<0.001); those with cystic fibrosis and fibrotic lung disease, including COVID-pulmonary fibrosis had higher transplant rates (p <0.001). Delisted patients had higher mean pulmonary artery pressures (32 mmHg vs. 29 mmHg, p=0.002), lower cardiac output (5.0 L/min vs. 5.5 L/min, p<0.001), and higher rates of prior cardiac surgery (8.9% vs. 4.6%, p=0.002). Both groups had similar rates of ventilator support (p=0.7) and dialysis (p>0.9) while on the waitlist. The main reason for delisting was death (41.2%), followed by worsening medical condition (32.2%). Conclusions: Pulmonary vascular disease, female sex, lower BMI, prior cardiac surgery, higher mean pulmonary artery pressures, and poor renal function were associated with higher rates of failed ECMO-bridge to transplant. While ECMO can be a bridge to lung transplantation, multiple patient-related factors may impact duration on the waitlist and, ultimately, successful lung transplantation.