Effect of abdominal aortic aneurysm sac shrinkage after endovascular repair on long-term outcomes between favorable and hostile neck anatomy

Abstract

ObjectiveThe aim of the present study was to analyze the influence of abdominal aortic aneurysm sac shrinkage on the long-term outcomes after endovascular aneurysm repair (EVAR) between patients with favorable and hostile neck anatomy. MethodsIn the present study, we retrospectively analyzed data from 268 patients with fusiform aneurysm and sac behavior who had been 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 end point was sac shrinkage, and the secondary end points included reintervention and a composite of rupture, type Ia endoleak, and late open conversion. ResultsNo differences were found in sac shrinkage between the patients with favorable and hostile neck anatomy (P = .47). Multivariate analysis revealed that an occluded inferior mesenteric artery (P = .04), the presence of posterior thrombus (P < .01), and no antiplatelet therapy (P = .01) were positive factors for sac shrinkage. The reintervention-free survival rate was better for patients with sac shrinkage compared with those without sac shrinkage regardless of the proximal neck anatomy (P < .01). The event-free survival rate of the composite end point at 5 and 10 years was 97.5% and 83.5% for patients with favorable neck anatomy and 86.8% and 81.0% for those with hostile neck anatomy, respectively (P = .02). In the subgroup with sac shrinkage, the event-free survival rates at 5 and 10 years were 98.7% and 98.7% for those with favorable neck anatomy and 92.7% and 82.4% for those with hostile neck anatomy, respectively (P = .02). In contrast, the event-free survival for patients without sac shrinkage did not differ between those with favorable and hostile neck anatomy (P = .08). Multivariate analysis showed that a hostile neck anatomy (hazard ratio, 3.32; 95% confidence interval, 1.26-8.80; P = .02) and no sac shrinkage (hazard ratio, 3.88; 95% confidence interval, 1.25-12.0; P = .02) were significant risk factors for the composite end point of rupture, type Ia endoleak, and late open conversion. ConclusionsProximal neck anatomy did not affect sac shrinkage after EVAR. Sac shrinkage has been a good surrogate marker of better long-term outcomes after EVAR for patients with favorable neck anatomy. In contrast, critical events such as rupture and type Ia endoleak can occur even after sac shrinkage has been achieved in patients with hostile neck anatomy.