Extracorporeal Membrane Oxygenation for COVID-19 During the Delta and Omicron Waves in North America

Clinical outcomes for patients with severe acute respiratory failure caused by different variants of the coronavirus disease 2019 (COVID-19) supported with extracorporeal membrane oxygenation (ECMO) are incompletely understood. Clinical characteristics, pre-ECMO management, and hospital mortality at 90 days for adults with COVID-19 who received venovenous ECMO (VV-ECMO) at North American centers during waves predominated by Delta (August 16 to December 12, 2021) and Omicron (January 31 to May 31, 2022) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants were compared in a competing risks framework. One thousand seven hundred and sixty-six patients (1,580 Delta, 186 Omicron) received VV-ECMO for COVID-19 during the Delta- and Omicron-predominant waves in North American centers. In the unadjusted competing risks model, no significant difference was observed in risk of hospital mortality at 90 days between patients during the Delta- versus Omicron-predominant wave (subhazard ratio [sHR], 0.94; 95% confidence interval [CI], 0.74-1.19), but patients supported with VV-ECMO during the Omicron-predominant wave had a significantly lower adjusted risk of hospital mortality at 90 days (subhazard ratio, 0.71; 95% CI, 0.51-0.99). Patients receiving VV-ECMO during the Omicron-predominant wave had a similar unadjusted risk of hospital mortality at 90 days, but a significantly lower adjusted risk of hospital mortality at 90 days than those receiving VV-ECMO during the Delta-predominant wave.