The effect of aortic morphology on perioperative rupture of abdominal aortic aneurysm-a retrospective cohort study.

Background: The high mortality from ruptured abdominal aortic aneurysm (AAA) is well-documented. However, the perioperative rupture risk is often underestimated. Aortic morphology is a key unresolved factor influencing this risk. This study aims to assess the impact of aortic morphology on the risk of perioperative rupture of AAAs.

Methods: A multicenter retrospective cohort study was conducted among patients undergoing perioperative endovascular aneurysm repair (EVAR) for AAAs between September 2017 and October 2021. All measurements were obtained using dedicated hospital reconstruction software. The primary endpoints were mortality and AAAs rupture. Univariate and multivariate logistic regression were used to analyze the association of risk factors with rupture. Piecewise linear regression was used to analyze the threshold effect of proximal neck angulation on rupture of AAAs. The clinical correlation between proximal aneurysm neck angulation and rupture was retrospectively studied after adjusting for potential confounders.

Results: A total of 160 patients were included. The incidence of AAAs rupture in patients with severe proximal aneurysm neck angulation was significantly higher than in patients without proximal aneurysm neck angulation (15.9% vs. 7.8%, P=0.001). After adjusting for gender, max aneurysm diameter and symptom, severe proximal aneurysm neck angulation was independently associated with AAAs rupture [odds ratio (OR) =8.159, 95% confidence interval (CI): 2.202-30.236; P=0.001]. After adjusting for gender, proximal aneurysm neck angulation and symptom, max aneurysm diameter was independently associated with AAAs rupture (OR =1.093, 95% CI: 1.046-1.143; P<0.001). The female seemed to have severe proximal neck angulation. When the angulation was greater than 41°, the risk of rupture increased linearly.

Conclusions: EVAR remains the preferred surgical approach for managing AAAs, guided by morphological and anatomical considerations. We have established a significant correlation between the extent of proximal neck angulation and the risk of perioperative rupture in aneurysms. Proximal neck angulation differs significantly between genders, with females exhibiting greater angulation than males. Clinicians should meticulously assess proximal neck angulation in patients undergoing EVAR and consider early intervention for those with severe angulation to mitigate the risk of rupture.