Retrospective analysis of predictors for sac size change following endovascular abdominal aortic aneurysm repair

<h2>Abstract</h2><h3>Objective</h3> The remodeling of the aortic aneurysm sac is a complex biological process, and the factors that influence sac regression following endovascular abdominal aortic aneurysm repair (EVAR) remain unclear. This study aimed to identify predictors of sac regression and assess its association with clinical outcomes in patients who underwent elective EVAR. <h3>Methods</h3> We retrospectively reviewed a cohort of 232 patients who underwent EVAR and had pre-operative and follow-up CT angiography (CTA). Patients were categorized into sac regression and sac non-regression based on CTA. Univariate and multivariate Cox proportional hazards models were used to identify factors predictive of sac regression. Additionally, we evaluated the association between aneurysm sac regression and clinical outcomes. <h3>Results</h3> Among the 232 patients included in the study, 124 patients (53.45%) experienced sac regression following EVAR. Univariate analysis revealed that sex, chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), glomerular filtration rate (GFR), total cholesterol (TC), endoleak II, use of statins, aortic aneurysm tortuosity index (TI) and severely angulated neck (SAN) of pre-EVAR and post-EVAR were associated with sac regression following EVAR. In multivariate analysis, type II endoleak (hazard ratio [HR], 0.15; 95% CI, 0.08 - 0.31; <i>P</i> < .001), SAN of post-EVAR (HR, 0.52; 95% CI, 0.28 - 0.98; <i>P</i> = .044), COPD (HR, 0.40; 95% CI, 0.23 - 0.71; <i>P</i> = .002) and greater TI (HR, 0.38; 95% CI, 0.23 - 0.60; <i>P</i> < .001) were identified as negative predictors of sac regression. Patients with non-regression of the sac had a significantly higher rate of aneurysm-related mortality (<i>P</i> = .031), re-intervention (<i>P</i> < .001) and delayed rupture (<i>P</i> = .015). <h3>Conclusions</h3> Our observational study suggests sac regression following EVAR is associated with improved clinical outcomes. The presence of COPD, endoleak II, a SAN of post-EVAR, and greater TI are identified as potential risk factors for sac non-regression.