Abstract:Background and Aims Type Ⅱ endoleak remains the most common complication after endovascular aneurysm repair (EVAR) and is closely associated with aneurysmal sac enlargement and secondary interventions. The inferior mesenteric artery (IMA) is a major source of type Ⅱ endoleak; however, the clinical benefit of prophylactic IMA embolization remains controversial. This study aimed to evaluate the impact of prophylactic IMA embolization on postoperative outcomes following EVAR.Methods Patients with infrarenal abdominal aortic aneurysm who underwent EVAR between January 2022 and January 2024 were retrospectively reviewed. Patients were divided into an embolization group and a non-embolization group according to whether prophylactic IMA embolization was performed. Baseline characteristics, perioperative data, and follow-up outcomes were compared. Kaplan-Meier analysis was used to assess endoleak-free survival, type Ⅱ endoleak-free survival, freedom from sac enlargement, and freedom from reintervention.Results A total of 233 patients were included, of whom 62 underwent prophylactic IMA embolization. No significant differences were observed in baseline clinical or anatomical characteristics between the embolization group and a non-embolization group (all P>0.05). During a mean follow-up of (19.6±9.7) months, the embolization group demonstrated significantly higher 2-year endoleak-free survival (93.55% vs. 74.53%, P=0.027), type Ⅱ endoleak-free survival (95.11% vs. 80.02%, P=0.043), IMA-related type Ⅱ endoleak-free survival (100.0% vs. 85.26%, P=0.019), and freedom from aneurysmal sac enlargement (94.27% vs. 81.96%, P=0.026) compared with the non-embolization group. No significant difference was observed in reintervention-free survival between the two groups (P=0.388).Conclusion Prophylactic IMA embolization significantly reduces postoperative endoleaks, particularly IMA-related type Ⅱ endoleaks, and is associated with improved control of aneurysmal sac enlargement after EVAR. However, its effect on reducing reintervention rates remains uncertain and warrants further validation in larger, long-term studies.