Preoperative Risk Stratification for Sac Enlargement and Reintervention Using Inferior Mesenteric Artery Patency and Lumbar Artery Burden After Endovascular Aneurysm Repair.

OBJECTIVE: To determine the optimal number of residual lumbar arteries (LAs) according to inferior mesenteric artery (IMA) patency and assess their associations with sac enlargement and reintervention after endovascular aneurysm repair (EVAR). METHODS: This retrospective single-center study included 335 patients who underwent EVAR for abdominal aortic aneurysm. Patients were stratified by postoperative IMA patency and residual lumbar artery (LA) count. Kaplan-Meier analyses with three prespecified dichotomizations were used to determine optimal risk-stratification cutoffs. RESULTS: Among 335 included patients, type II endoleak incidence increased with greater residual LA burden and was consistently higher in those with a patent IMA than in those with a non-patent IMA (P < .001 for all comparisons). Based on previously reported long-term open repair outcomes, patients with a non-patent IMA and ≥3 residual LAs or a patent IMA and ≥2 residual LAs were classified as high risk. Kaplan-Meier analysis showed significantly lower 10-year freedom from sac enlargement > 5 mm and reintervention in the high-risk than in the low-risk group (35% vs 92% and 70% vs 98%, respectively, both P < .0001). In multivariable Cox regression, each additional residual LA was independently associated with increased risks of sac enlargement >5 mm (HR, 1.83; 95% CI, 1.59-2.12; P < .001) and reintervention (HR, 1.79; 95% CI, 1.39-2.32; P < .001), whereas patent IMA was independently associated with sac enlargement but not with reintervention. CONCLUSIONS: Following EVAR, fewer residual LAs were associated with improved outcomes; optimal thresholds differed by IMA patency and may aid risk stratification and treatment planning.