b'Of the 588,203 patients evaluated in the CARES registry 22,104 (3.76%) patients met clinical eligibility. When transportation time to an ECMO-ready center was accounted for, the ECPR eligible patients in the CARES registry further decreased to 4,466 (0.76%) to 13,828 (2.35%) patients, based on 15- and 45-minute transport times, respectively (Table 1). Finally, after applying the ROC-PRIMED model for time-dependent rates of ROSC the final eligibility was determined to be 4,027 (0.68%) to 9,889 (1.68%) patients, based on 15- and 45-minute transport times, respectively. By utilizing the CARES registry and ROC-PRIMED database to account for proximity to centers with ECMO capabilities and the likelihood of ROSC prior to arrival, respectively, our methods likely provide the most accurate estimation of ECPR eligibility for OHCA patients to date in the U.S.Time Dependent Rates of ECPR Eligibility based off the ROC-PRIMED OHCA database Table 1: *(1) initial shockable cardiac rhythm, (2) witnessed arrest, (3) bystander CPR, (4) presumed cardiac etiology of arrest, (5) age65. **The percent eligible compared to the total number OHCA in the same periodOHCA=out of hospital cardiac arrest; ECPR=extracorporeal cardiopulmonary resuscitation; CARES=National Cardiac Arrest Registry to Enhance Survival; PCI=Percutaneous Coronary Intervention; GIS= Geographic Information System While our ECPR eligibility estimation is lower than previously reported, our models still conservatively demonstrate nearly 2,500 potential lives saved over seven years, using 1.68% (9,889/588,203) eligibility from the 45-minute transportation time to an ECMO-ready center model and an assumed 25% survival to hospital discharge with favorable neurologic outcome. Future work utilizing our GIS model and the CARES registry could focus on determining the current access of OHCA patients to ECMO centers based on different population demographics and the effect of alternative ECPR systems of care which could inform future public health planning efforts. ECMO-ready, ECMO-capable, and PCI-capable GIS Models Figure 1: Displays the 15-minute, 30 minutes, and 45-minute drive time buffers around (A) ECMO-ready centers (B) ECMO-capable centers and (C) PCI-capable centers in the U.S. ECMO: Extracorporeal Membrane Oxygenation, PCI: Percutaneous coronary intervention, GIS: Geographic Information System. 4Gottula AL, Shaw CR, Gorder KL, Lane BH, Latessa J, Qi M, Koshoffer A, Al-Araji R, Young W, Bonomo J, Langabeer JR, Yannopoulos D, Henry TD, Hsu CH, Benoit JL.Eligibility of out-of-hospital cardiac arrest patients for extracorporeal cardiopulmonary resuscitation in the United States: A geographic information system model.Resuscitation. 180:111-120. Figure used with permission of Elsevier from Gottula AL et al. Eligibility of out-of-hospital cardiac arrest patients for extracorporeal cardiopulmonary resuscitation in the25United States: A geographic information system model. Resuscitation. 180:111-120 (2022). Permission conveyed through Copyright Clearance Center Inc.'