Aneurysm Risk Index as a Novel Method to Evaluate Abdominal Aortic Aneurysms: A Proof-of-Concept Study

Abdominal aortic aneurysm (AAA) maximum aortic diameter (AD) guides surveillance and timing of elective repair. However, rupture can occur at smaller thresholds than recommended for repair. We propose the Aneurysm Risk Index (ARI), an adjunctive method of aortic aneurysm measurement that we hypothesize correlates AAA rupture risk.

This single center retrospective cohort study used an institutional database of patients with known AAA from 1996 to 2020 divided into 3 groups: surveillance, elective repair, and rupture. Maximum vessel diameter measurements were recorded from 3-dimensional aortic reconstructions using the most recent imaging available prior to any intervention. ARI was calculated by dividing the patient's maximum AD by average external iliac artery diameter. Differences in ARI were compared with AD based on aneurysm groups and sex.

Each group included 42 patients (50% female) for a total of 126 patients. There were significant differences in mean ARI and mean AD between groups. Women in the surveillance group had a higher mean ARI than men (4.7 vs. 5.8, respectively, P = 0.03), but there were no significant differences in ARI between women and men in the elective repair and rupture cohorts. There were significant differences between sexes in mean AD of the elective and rupture cohorts (P < 0.001 and P < 0.001, respectively).

ARI is an adjunctive technique that accounts for individual variation and sex-related differences in AAA measurements. Prospective studies with larger sample sizes are needed to identify the ideal ARI threshold for AAA surveillance and repair.