b'Scientific Session Abstracts SATURDAY APRIL 20, 2024 20: THE IMPACT OF LOW BMI ON PERIOPERATIVE AND LONG-TERM OUTCOMES AFTER TEVARDonna Bahroloomi, MD, Lili Sadri MD, Fred Weaver, Santo Trimarch,Donald Baril, MD, Elizabeth Chou, MD, Ali Azizzadeh, MDCedars-Sinai Medical CenterBackground:While several studies have evaluated the impact of elevated body mass index (BMI) on outcomes after endovascular abdominal aortic aneurysm repair (EVAR), the relationship between underweight and long-term outcomes after thoracic endovascular aortic aneurysm repair (TEVAR) remains poorly understood. We investigated the role of low BMI on clinical and technical outcomes in patients who underwent TEVAR.METHODS: The Global Registry for Endovascular Aortic Treatment (GREAT) Registry is an ongoing multicenter, multi-national, observational cohort study between August 2010-September 2016. All patients treated with Conformable GORE TAG Thoracic Endoprosthesis devices were included. Patients were considered underweight with BMI <23 kg/m2 according to National Institute of Health guidelines for patients 65 years. Normal BMI was defined byBMI 23-25 kg/m2. Long-term patient follow-up was assessed annually, up to 7 years post- intervention. Primary outcomes were technical surgical complications, including rates ofendoleak, rupture, and migration. Secondary outcomes included postoperative complications.RESULTS: Out of 884 patients undergoing TEVAR, 161 (18%) were defined as underweight. 129(15%) were considered normal-weight, and 594 (67%) had BMI>25. One year postoperatively, there was no statistically significant difference in rates of endoleak (5.0% vs 6.2%, p=0.3) (Table 1). Underweight patients developed significantly higher rates of aortic rupture than normal weight patients at 1 year (3.1% vs 1.6%, p=0.02). After 2-3 years postoperatively, underweight patients had significantly higher rates of Type 1B endoleak when compared to normal weight patients (5.2% vs 1.3%, p=0.01). No difference in endoleak, migration, or rupture rates existed between underweight groups after 4-7 yrs postoperatively. No significant difference in reintervention rates was identified throughout all follow-up intervals. Interestingly, the rate of all-cause mortality was significantly higher in the normal weight patients than underweight patients at the 1-year (17.4% vs 15.5%, p=0.03) and 2-3 year (11.1% vs 20.0%, p=.0006) intervals postoperatively. No significant difference in mortality was determined between the groups after 4-7 years postoperatively (Table 1).CONCLUSIONS: Patients with low BMI undergoing TEVAR experience higher rates of aortic rupture and Type 1B endoleak, with no significant difference in postoperative reintervention rates. These findings should be considered in risk reduction and preoperative optimization of patients considered for TEVAR.42 NDANNUAL MEETING|APRIL 1921, 2024|OCEANSIDE, CA 59'