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Introduction: After five randomized trials in 2015 demonstrating benefit, endovascular therapy (EVT) is the new standard of care for selected acute ischemic stroke (AIS) patients. Stroke systems must rapidly adapt to provide this time-sensitive therapy to eligible patients.Objective: To estimate the number of EVT-eligible AIS patients in the US annually using Class I and IIa eligibility criteria from the 6/2015 AHA/ASA guideline update.Methods: We ascertained all hospitalized AIS patients ≥18 years old in 2010 using ICD-9 codes 430-436 within the 1.3 million Greater Cincinnati/Northern Kentucky (GCNK) population. Two groups were selected: (1) IV rtPA (IVT)-eligible: arrival ≤3.5 hours from onset and no standard contraindications, and (2) IVT-ineligible but potentially EVT-eligible: arrival ≤5 hours from onset, NIHSS ≥6, platelets ≥50k, and INR ≤3.0. For each group, we estimated the rate of large-vessel occlusion (LVO) by baseline NIHSS using a 2,152-patient prospective database at University of Bern. Other criteria included prestroke mRS 0-1 and ASPECTS ≥6 (estimated 75% prevalence). We also considered expanded eligibility of mRS 0-3 and ASPECTS ≥5 (estimated 85% prevalence). Regional rates were age/race/sex-adjusted to 2010 US census data.Results: Regional eligibility for IVT and EVT among 2297 AIS patients is shown in the Figure. Projecting to the US, 30,607 patients would be IVT-eligible, and 5582 patients would be EVT-eligible annually. Expanded EVT eligibility would lead to 18,094 EVT-eligible patients nationally.Conclusion: Within the GCNK population, 1.0% of AIS patients (including 11.3% of IVT-eligible patients) are EVT-eligible based on Class I and IIa AHA/ASA recommendations. We project 5582 EVT-eligible patients in the US annually, and up to 18,094 using expanded eligibility. Estimates are limited by the use of cohort-based LVO and ASPECTS rates, and the projection of urban GCNK region arrival time patterns to the broader US population.