BACKGROUND Timing of surgical revascularization for acute coronary syndrome remains debated. We assessed the impact of timing to coronary artery bypass grafting (CABG) on mortality and resource utilization in a national cohort. METHODS Adults admitted for acute coronary syndrome in the 2009-2018 National Inpatient Sample were grouped by time from coronary angiography to CABG (Dt): 0, 1-3, 4-7, and >7 days. Generalized linear models were fit to evaluate associations between Dt and in-hospital mortality and hospitalization costs. Timing and mortality of CABG for acute coronary syndrome were compared between high-performing hospitals (below the median risk adjusted mortality for all CABG and valve operations) and others. RESULTS Of 444,065 patients, Delta t = 0 days in 12.3%, Delta t = 1-3 days in 57.3%, Delta t = 4-7 days in 26.3%, and Delta t > 7 days in 4.2%. Risk-adjusted mortality was greatest at Delta t = 0 days (4.5%, 95% confidence interval [CI], 4.1%-4.9%) and Delta t > 7 days (4.0%, 95% CI 3.4%-4.7%), but similar for operations performed at Delta t = 1-3 days (1.8%, 95% CI 1.7%-1.9%) and Delta t = 4-7 days (2.1%, 95% CI 1.9%-2.3%). Compared to Delta t = 1-3 days, hospitalization costs were greater by $6,400 (95% CI $5,900-$6,900) for Delta t = 4-7 days and $21,200 (95% CI $19,800-$22,600) for Delta t > 7 days. High-performing hospitals had similar time to CABG as others (2 vs 2 days, P = .17), but lower mortality (0.9% vs 3.3%, P <.001). CONCLUSIONS Revascularization on days 1-3 and 4-7 led to comparable in-hospital mortality, with greater rates on day 0 and after day 7. Costs were greater for revascularization at days 4-7 compared with days 1-3. These findings support the reduction of time to revascularization to 1-3 days when deemed clinically appropriate and feasible. (C) 2022 by The Society of Thoracic Surgeons. Published by Elsevier Inc.