LAUSR

OBJECTIVE The aim of the present study was to analyze the influence of abdominal aortic aneurysm sac shrinkage on long-term outcomes after endovascular aneurysm repair (EVAR) between patients with favorable and hostile neck anatomy. METHODS This study retrospectively analyzed data from 268 patients with fusiform aneurysm and sac behavior who were evaluated for ≥1 year after EVAR. Hostile neck anatomy was defined as a proximal aneurysmal neck length of <10 mm or proximal neck angle of ≥60°. The primary endpoint was sac shrinkage, and the secondary endpoints included re-intervention and a composite of rupture, type 1a endoleak, and late open conversion. RESULTS There was no difference in sac shrinkage between patients with favorable and hostile neck anatomy (P = .47). Multivariate analysis revealed that occluded inferior mesenteric artery (P = .04), presence of posterior thrombus (P < .01), and no antiplatelet therapy (P = .01) were positive factors for sac shrinkage. The re-intervention free survival rate was better in patients with sac shrinkage compared with those without sac shrinkage regardless of proximal neck anatomy (P < .01). The event-free survival rate of the composite endpoint at 5 and 10 years were 97.5% and 83.5% in patients with favorable neck, and 86.8% and 81.0% in those with hostile neck (P = .02). In the subgroup with sac shrinkage, the event-free survival rates at 5 and 10 years were 98.7% and 98.7% in patients with favorable neck, and 92,7% and 82.4% in those with hostile neck (P = .02). In contrast, the event-free survival of patients without sac shrinkage did not differ between those with favorable and hostile neck (P = .08). Multivariate analysis showed that hostile neck anatomy (Hazard ratio [HR], 3.32; 95% confidence interval [CI], 1.26-8.80; P = .02) and no sac shrinkage (HR, 3.88; 95% CI, 1.25-12.0; P = .02) were significant risk factors for composite of rupture, type 1a endoleak, and late open conversion. CONCLUSIONS Proximal neck anatomy did not affect sac shrinkage after EVAR. Sac shrinkage is a good surrogate marker of better long-term outcomes after EVAR in patients with favorable neck anatomy. In contrast, critical events such as rupture or type 1a endoleak may occur even after sac shrinkage has been achieved in patients with hostile neck anatomy.