b'Scientific Session Abstracts SUNDAY APRIL 21, 2024 30: EARLY GRAFT THROMBOSIS IN LOWER EXTREMITYARTERIAL BYPASS: IDENTIFYING PROGNOSTIC FACTORSDURING INDEX ADMISSIONMohammed Hamouda, MD 1 , Mokhshan Ramachandran, BS 1,Jonathan T. Unkart, MD, MPH 2 , Andrew Barleben MD 1 ,Mahmoud B. Malas MD, MHS, FACS, RPVI 1 .1Center for Learning and Excellence in Vascular and Endovascular Research (CLEVER), Department of Surgery, Division of Vascular & Endovascular Surgery,UC San Diego, San Diego, California,2SUNY Downstate Department of SurgeryBackground: Early graft thrombosis following lower extremity bypass (LEB) has long served as a quality indicator of surgical management. A granular understanding of the risk factors for graft thrombosis could mitigate the potentially avoidable sequelae of this complication. Our study utilized Vascular Quality Initiative (VQI) data to identify predictor variables associated with graft thrombosis during index admission following LEB.Methods: We queried the VQI database for patients receiving unilateral infrainguinal LEB between 2003- 2022 and excluded patients undergoing concomitant PVI or suprainguinal bypass. We formed 6 procedural groups: femoral-above knee popliteal bypass, femoral-below knee popliteal bypass, femoral-tibial bypass, femoral-ankle bypass, popliteal-tibial bypass, and popliteal-ankle bypass. Among these 6 groups, we utilized multivariable logistic regression to identify technical and perioperative characteristics that predicted early graft thrombosis.Results: Of the 54,504 LEB procedures that met inclusion criteria, 11,906 (21.8%) underwent femoral-above knee popliteal, 17,541 (32.2%) femoral-below knee popliteal, 19,224 (35.3%) femoral-tibial, 1,414 (2.6%) femoral-ankle, 2,661 (4.9%) popliteal-tibial and 1,758 (3.2%) popliteal-ankle bypass procedures. At time of discharge, 1,012 (1.9%) required intervention for a thrombotic intervention and 814 (1.5%) were occluded. After adjusting for patient characteristics and comorbidities, we identified the following independent predictors for early graft thrombosis: female gender, distal target, symptomatic indication (rest pain and tissue loss), urgent/emergent presentation, and certain anticoagulation therapy. Conversely, use ofpreoperative statin, aspirin and clopidogrel were protective against early graft thrombosis (Table I). We found that 9.5% of the population were not receiving one or several of the protective medications identified (25.9% not receiving statins, 69.1% not receiving clopidogrel and 27.6% not receiving aspirin). Additionally, native vein conduits demonstrated lowest odds of graft thrombosis (Table I, Figure 1).Conclusion: In this large national study of LEB, we identified several factors including distal target, urgent/emergent presentation, preoperative warfarin or rivaroxaban therapy and use of non-autologous conduits as independent predictors of graft thrombosis. Conversely, preoperative statin, antiplatelet 78SOUTHERN CALIFORNIA VASCULAR SURGICAL SOCIETY'