Rupture Risk of Small Abdominal Aortic Aneurysms

Abstract

INTRODUCTION: The risk of rupture of small abdominal aortic aneurysms (AAA) is poorly understood, yet critical for determining optimal guidelines for surveillance and repair. We describe the rupture risk of patients with small AAA. METHODS: Patients from a prospective aneurysm surveillance registry with unrepaired, small AAA (≤5.5 cm in men, ≤5.0 cm in women) from 2003-2020 were included. Outcomes of interest included confirmed rupture, probable rupture, AAA repair, and mortality. Cumulative incidence of rupture was calculated using a nonparametric cumulative incidence function accounting for competing events of death, aneurysm repair, and growth to a large size. RESULTS: There were 21,499 patients with small AAA; mean age was 73 +/- 9 years, 20% of patients were female, 80% white, and 16% smokers. Overall, 21% (n = 4,515) of patients progressed to a large size during the study period over a median time of 4.1 years (IQR 0.9-7.3). Among patients with small AAA undergoing repair (n = 503), 37 were symptomatic and 14 had ruptured. There were 19 confirmed and 5 probable ruptures. The cumulative incidence of rupture was 0.03% at 1 year and 0.04% at 2 and 3 years. Aortic diameter prior to rupture can be seen in the Figure. Overall mortality for the cohort was 22%, 33%, and 41% at 1, 2, and 3 years, respectively. CONCLUSION: The risk of rupture of small aneurysms is exceedingly low, particularly in the setting of high mortality from non-aortic pathology in this patient population. Therefore, surveillance guidelines should focus on a patient’s risk of reaching size threshold for repair.Figure