b'Scientific Session Abstracts SUNDAY APRIL 21, 202444: MORTALITY FOLLOWING INFRAINGUINAL BYPASS VERSUS ENDOVASCULAR TREATMENT OF PERIPHERAL ARTERY DISEASE BY BODY MASS INDEXMikayla Kricfalusi BA1 ; Mohammed Hamouda MD2 ; Ahmed Abdelkarim MD2 ;Alik Farber, MD3 , Mahmoud B. Malas MD, MHS, RPVI, FACS21 California University of Science and Medicine, School of Medicine,2Center for Learning and Excellence in Vascular and Endovascular Surgery (CLEVER), Department of Surgery, Division of Vascular and Endovascular Surgery, UC San Diego3Boston Medical CenterBackground: Obese patients have higher rates of cardiovascular disease and associated risk factors, but lower rates of peripheral artery disease (PAD) and better outcomes following revascularization. This results in an obesity paradox, where obese patients have the lowest risk of adverse outcomes following treatment, while underweight and morbidly obese patients are at the highest risk. No previous studies have compared outcomes of endovascular vs open bypass within each body mass index (BMI) group. Our study aims to help stratify the risk of interventions [Peripheral Vascular Intervention (PVI) or infrainguinal bypass (IIB)] for patients depending on BMI.Methods: The Vascular Quality Initiative database was queried for patients presenting with Claudication or Critical Limb Ischemia undergoing PVI or IIB (using great saphenous vein) from 2012 to 2023. Patients were stratified into five groups based on BMI: underweight (BMI18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2), obese (BMI 30-39.9 kg/m2), and morbidly obese (BMI 40-49.9 kg/m2). Multivariable logistic regression analysis compared in-hospital and 30-day mortality for IIB vs PVI within each BMI group. Cox regression and Log Rank test analyzed 1-year mortality.Results: 117,588 patients met the study criteria, including 4,485 underweight (3.8%), 35,407 normal weight (30.1%), 38,870 overweight (33.1%), 34,381 obese (29.2%), and 5,244 morbidly obese (4.5%) patients. There was no difference in mortality between PVI and IIB among underweight patients, however IIB was associated with 40% increase in-hospital mortality (OR 1.4, 95% CI (1.02,1.91) p=0.036), in normal weight patients and double the odds of in-hospital mortality (OR 1.97, 95% CI (1.44,2.70) p 0.001) in obese and morbidly obese patients (OR 2.21, 95% CI (1.05,4.65) p=0.037), compared to PVI (Table I). Bypass was associated with lower risk of 1-year mortality among the normal weight (HR 0.80, 95% CI (0.72,0.87) p 0.001), overweight (HR 0.87, 95% CI (0.80,0.97) p=0.010), and obese patients (HR 0.85, 95% CI (0.75,0.96) p=0.008), compared to PVI. Among morbidly obese patients, there was no significant difference in 1-year survival (Table II). Conclusion: zThis large national study shows significant differences in postoperative and 1-year mortality between PVI and IIB depending on patient BMI. For normal weight and obese patients, PVI was associated with decreased in-hospital mortality, however, IIB patients had better 1-year survival for all BMI groups but the underweight and morbidly obese. This suggests a long-term survival benefit following IIB compared to PVI, except for patients otherwise at a higher risk of mortality regardless of procedure choice.112SOUTHERN CALIFORNIA VASCULAR SURGICAL SOCIETY'