Background: In the AUGUSTUS trial (An Open-Label, 2 x 2 Factorial, Randomized Controlled, Clinical Trial to Evaluate the Safety of Apixaban vs Vitamin K Antagonist and Aspirin vs Aspirin Placebo in Patients With Atrial Fibrillation and Acute Coronary Syndrome or Percutaneous Coronary Intervention), the combination of dual antiplatelet therapy plus oral anticoagulation increased the risk of bleeding without reducing ischemic events compared with a P2Y12 inhibitor plus oral anticoagulation among patients with atrial fibrillation and acute coronary syndrome or elective percutaneous coronary intervention. However, AUGUSTUS enrolled patients up to 14 days after acute coronary syndrome or percutaneous coronary intervention, and there may be a benefit to dual antiplatelet therapy plus oral anticoagulation early after an ischemic event., Methods: In this secondary analysis of AUGUSTUS, we divided patients into groups based on whether they were enrolled <6 days (early) or ≥6 days (later) after their index acute coronary syndrome or percutaneous coronary intervention, and tested the interaction between time from the index event to enrollment and randomized treatment (apixaban versus vitamin K antagonist and aspirin versus placebo) on 30-day and 6-month clinical outcomes using Cox proportional hazards models., Results: Among 4605 patients enrolled in AUGUSTUS with data available on time from the index event to enrollment, the median time from the index event to enrollment was 6 (range, 0-14) days. There were no significant interactions between time from the index event and aspirin versus placebo on clinical outcomes at 30 days or 6 months, though patients with time from the index event <6 days had a nominally significant reduction in death or ischemic events at 30 days with aspirin (hazard ratio, 0.55 [95% CI, 0.30-0.99]), whereas patients with time from the index event ≥6 days did not (hazard ratio, 0.88 [95% CI, 0.54-1.43]; interaction P =0.23). There were no significant interactions between time from the index event and apixaban versus vitamin K antagonist on clinical outcomes., Conclusions: Among patients with atrial fibrillation with acute coronary syndrome or undergoing percutaneous coronary intervention, there was no difference in the relative benefit of apixaban versus vitamin K antagonist or aspirin versus placebo when patients were enrolled early versus later after their index event., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02415400., Competing Interests: Dr Fanaroff: research grants from the American Heart Association, National Institutes of Health, and Cardiovascular Systems Inc; and consulting fees from Intercept Pharmaceuticals and Abbott Laboratories. Dr Granger: research grants from Bayer, Boehringer Ingelheim, Bristol Myers Squibb, Daiichi Sankyo, Janssen, Pfizer, Armetheon, AstraZeneca, US Food and Drug Administration (FDA), GlaxoSmithKline, The Medicines Company, Medtronic Foundation, Medtronic, Inc, and Novartis; consulting fees from Bayer, Boehringer Ingelheim, Boston Scientific, Bristol Myers Squibb, Daiichi Sankyo, Janssen, Pfizer, Abbvie, Armetheon, AstraZeneca, Eli Lilly, Gilead, GlaxoSmithKline, Hoffmann-La Roche, The Medicines Company, National Institutes of Health (NIH), Novartis, Sirtex, Verseon, Apple, Medscape, LLC, Merck, Novo Nordisk, Roche Diagnostics, and Rho Pharmaceuticals. Dr Goodman: research grant support and speaker/consulting honoraria from Amgen, Anthos Therapeutics, AstraZeneca, Bayer, Boehringer Ingelheim, Bristol Myers Squibb, CSL Behring, CYTE, Ltd, Daiichi-Sankyo/American Regent, Eli Lilly, Esperion, Ferring Pharmaceuticals, HLS Therapeutics, JAMP Pharma, Merck, Novartis, Novo Nordisk A/C, Pendopharm/Pharmascience, Pfizer, Regeneron, Sanofi, Servier, Tolmar Pharmaceuticals, and Valeo Pharma; salary support/honoraria from the Heart and Stroke Foundation of Ontario/University of Toronto (Polo) Chair, Canadian Heart Failure Society, Canadian Heart Research Centre and MD Primer, Canadian Virtual Coordinating Centre for Global Collaborative Cardiovascular Research, Cleveland Clinic Coordinating Centre for Clinical Research, Duke Clinical Research Institute, New York University Clinical Coordinating Centre, Baim Institute for Clinical Research, and Thrombolysis in Myocardial Infarction Study Group (Brigham Health). Dr Aronson: employee of Bristol Myers Squibb. Dr Windecker: research, travel, or educational grants to the institution without personal remuneration from Abbott, Abiomed, Amgen, AstraZeneca, Bayer, Braun, Biotronik, Boehringer Ingelheim, Boston Scientific, Bristol Myers Squibb, Cardinal Health, CardioValve, Cordis Medical, Corflow Therapeutics, CSL Behring, Daiichi Sankyo, Edwards Lifesciences, Farapulse, Inc, Fumedica, Guerbet, Idorsia, Inari Medical, InfraRedx, Janssen-Cilag, Johnson & Johnson, MedAlliance, Medicure, Medtronic, Merck Sharp & Dohm, Miracor Medical, Novartis, Novo Nordisk, Organon, OrPha Suisse, Pharming Tech, Pfizer, Polares, Regeneron, Sanofi-Aventis, Servier, Sinomed, Terumo, Vifor, and V-Wave; advisory board member and steering/executive group member of trials funded by Abbott, Abiomed, Amgen, AstraZeneca, Bayer, Boston Scientific, Biotronik, Bristol Myers Squibb, Edwards Lifesciences, MedAlliance, Medtronic, Novartis, Polares, Recardio, Sinomed, Terumo, and V-Wave, with payments to the institution but no personal payments; steering/executive committee group member of several investigator-initiated trials funded by industry without impact on his personal remuneration. Dr Mehran: institutional research grants from AstraZeneca, Bayer, Beth Israel Deaconess, Bristol Myers Squibb/Sanofi, CSL Behring, Eli Lilly/Daiichi Sankyo, Medtronic, Novartis, and OrbusNeich; consulting fees from Boston Scientific, Abbott Vascular, Medscape, Siemens Medical Solutions, Roivant Sciences, Inc, and Sanofi; consulting (no fees) to Regeneron Pharmaceuticals, Inc; institutional consulting fees from Abbott Vascular, Spectranetics/Phillips/Volcano Corporation, Bristol Myers Squibb, Novartis, and Watermark Research; executive committee member for Janssen Pharmaceuticals and Bristol Myers Squibb; <1% equity in Claret Medical and Elixir Medical. Dr Alexander: research grants from Bristol Myers Squibb, Boehringer Ingelheim, AstraZeneca, CryoLife, CSL Behring, US FDA, NIH, Sanofi, and VoluMetrix; consulting fees from Pfizer, Bristol Myers Squibb, AbbVie Pharmaceuticals, CSL Behring, Novo Nordisk, Portola Pharmaceuticals, Quantum Genomics, Teikoku Pharmaceuticals, VA Cooperative Studies, and Zafgen. Dr Lopes: research grants from Bristol Myers Squibb, Pfizer, Amgen, Inc, GlaxoSmithKline, Medtronic PLC, and Sanofi Aventis; consulting fees from Bristol Myers Squibb, Pfizer, Boehringer Ingelheim, and Bayer AG. The other authors report no conflicts.