Objective: Antiplatelet and/or anticoagulant therapy are commonly prescribed after fenestrated/branched endovascular aortic repair (F/BEVAR). However, the optimal regimen remains unknown. We sought to characterize practice patterns and outcomes of antiplatelet and anticoagulant use in patients who underwent F/BEVAR., Methods: Consecutive patients enrolled (2012-2023) as part of the United States Aortic Research Consortium (US-ARC) from 10 independent physician-sponsored investigational device exemption studies were evaluated. The cohort was characterized by medication regimen on discharge from index F/BEVAR: (1) Aspirin alone OR P2Y12 alone (single-antiplatelet therapy [SAPT]); (2) Anticoagulant alone; (3) Aspirin + P2Y12 (dual-antiplatelet therapy [DAPT]); (4) Aspirin + anticoagulant OR P2Y12 + anticoagulant (SAPT + anticoagulant); (5) Aspirin + P2Y12 + anticoagulant (triple therapy [TT]); and (6) No therapy. Kaplan-Meier analysis and Cox proportional hazards modeling were used to compare 1-year outcomes including survival, target artery patency, freedom from bleeding complication, freedom from all reinterventions, and freedom from stent-specific reintervention., Results: Of the 1525 patients with complete exposure and outcome data, 49.6% were discharged on DAPT, 28.8% on SAPT, 13.6% on SAPT + anticoagulant, 3.2% on TT, 2.6% on anticoagulant alone, and 2.2% on no therapy. Discharge medication regimen was not associated with differences in 1-year survival, bleeding complications, composite reintervention rate, or stent-specific reintervention rate. However, there was a significant difference in 1-year target artery patency. On multivariable analysis comparing with SAPT, DAPT conferred a lower hazard of loss of target artery patency (hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.27-0.84; P = .01). On sub-analyses of renal stents alone or visceral stents alone, DAPT no longer had a significantly lower hazard of loss of target artery patency (renal: HR, 0.66; 95% CI, 0.35-1.27; P = .22; visceral: HR, 0.31; 95% CI, 0.05-1.9; P = .21). Lastly, duration of DAPT therapy (1 month, 6 months, or 1 year) did not significantly affect target artery patency., Conclusions: Practice patterns for antiplatelet and anticoagulant regimens after F/BEVAR vary widely across the US-ARC. There were no differences in bleeding complications, survival or reintervention rates among different regimens, but higher branch vessel patency was noted in the DAPT cohort. These data suggest there is a benefit in DAPT therapy. However, the generalizability of this finding is limited by the retrospective nature of this data, and the clinical significance of this finding is unclear, as there is no difference in survival, bleeding, or reintervention rates amongst the different regimens. Hence, an "optimal" regimen, including the duration of such regimen, could not be clearly discerned. This suggests equipoise for a randomized trial, nested within this cohort, to identify the most effective antiplatelet/anticoagulant regimen for the growing number of patients being treated globally with F/BEVAR., Competing Interests: Disclosures A.S. reports consultant for Artivion, Cook Medical, and Philips; and receives research support from Cook Medical and Philips. All proceeds go to the UMass Memorial Hospital Foundation. A.W.B. reports onsultant for Artivion, Cook Medical, Medtronic, Philips, and Terumo Aortic; and receives research support from Cook Medical, Endospan, Medtronic, Philips, Terumo Aortic, and W.L. Gore & Associates. All proceeds go to the University of Alabama at Birmingham. M.A.F. reports consultant for WL Gore, Cook Medical, ViTAA, Centerline Biomedical, and Getinge; and receives research support from Cook Medical, WL Gore ViTAA, and Centerline Biomedical. W.A.L. reports consultant for Terumo Aortic. G.S.O. reports consultant for Cook, Centerline Biomedical, GE Healthcare, and Gore; and receives research support from GE Healthcare. F.E.P. reports stock options from Centerline Biomedical; and receives research support from Cook Medical. D.B.S. reports consultant for WL Gore, Cook Medical, Medtronic, and Philips; and receives research support from Cook Medical, Philips, and W.L. Gore. C.H.T. reports consultant for Cook Medical, WL Gore, and Philips; and receives research support from Cook Medical, Philips, and WL Gore., (Copyright © 2024 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)