Association between abdominal aortic aneurysm sac shrinkage and aneurysm wall enhancement after endovascular aneurysm repair.

Abstract

Aneurysm sac shrinkage after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms has clinical significance. In this study, we analyzed sac shrinkage after EVAR, focusing on aneurysm wall enhancement (AWE). This single-center retrospective cohort study included 355 patients who underwent elective bifurcated EVAR for infrarenal abdominal aortic aneurysms between June 2007 and December 2020. AWE was assessed using computed tomography angiography performed 3 to 12 months after surgery. The primary outcome was sac shrinkage, which was defined as a ≥5 mm decrease in sac diameter after 3 years. A persistent type II endoleak (pT2EL) was defined as any type II endoleak lasting ≥6 months postoperatively. The associations between AWE and sac shrinkage were analyzed via Kaplan-Meier analysis and subgroup analysis of patients with pT2ELs. Of the 355 patients, 187 (52.7%) exhibited signs of sac shrinkage. AWE was significantly more common in the sac shrinkage group than in the nonshrinkage group (72.2% vs 51.8%; P < .0001). Multivariate analysis identified AWE as a factor significantly contributing to sac shrinkage 3 years after EVAR (P = .0002; odds ratio [OR], 4.10; 95% confidence interval [CI], 1.87-8.98). Having fewer than five patent lumbar arteries preoperatively was also associated with sac shrinkage (P = .0020; OR, 2.10; 95% CI, 1.31-3.36). According to the Kaplan-Meier curves, the AWE group exhibited significant sac shrinkage (log-rank test; P < .0001). In a subgroup analysis of patients who developed pT2EL, AWE was the only factor significantly contributing to sac shrinkage 3 years after EVAR (P = .0002; OR, 4.10; 95% CI, 1.87-8.98). This study revealed a significant association between AWE and sac shrinkage after EVAR. Further research, including histopathological studies, is needed to elucidate the mechanism of the association between sac dynamics and AWE.