Characteristics and 1-year outcomes of patients with rupture of small abdominal aortic aneurysms

Abstract

Objectives: Ruptured abdominal aortic aneurysms (rAAA) are associated typically with a large sac diameter; however, some patients experience rupture before reaching operative thresholds for elective repair. We aim to investigate the characteristics and outcomes of patients who experience small rAAA.

Methods: The Vascular Quality Initiative database for open AAA repair and endovascular aneurysm repair from 2003 to 2020 were reviewed for all rAAA cases. Based on the 2018 Society for Vascular Surgery guidelines on operative size thresholds for elective repair, patients with infrarenal aneurysms of less than 5.0 cm in women or less than 5.5 cm in men were categorized as a small rAAA. Patients who met operative thresholds or had a concomitant iliac diameter 3.5 cm or greater were categorized as a large rAAA. Patient characteristics and perioperative as well as long-term outcomes were compared via univariate regression. Inverse probability of treatment weighting using propensity scores was used to examine the relationship between rAAA size and adverse outcomes.

Results: There were 3962 cases that met inclusion criteria, with 12.2% small rAAA. The mean aneurysm diameter was 42.3 mm and 78.5 mm in the small and large rAAA groups, respectively. Patients in the small rAAA group were significantly more likely to be younger, African American, have a lower body mass index, and had significantly higher rates of hypertension. Small rAAA were more likely to be repaired via endovascular aneurysm repair (P = .001). Hypotension was significantly less likely in patients with small rAAA (P<.001). Rates of perioperative myocardial infarction (P < .001), total morbidity (P < .004) and mortality (P < .001) were significantly higher for large rAAA cases. After propensity matching, there was no significant difference in mortality between the two groups, but smaller rAAA was associated with lower rates of myocardial infarction (odds ratio, 0.50; 95% confidence interval, 0.31-0.82). On long-term follow-up, no difference in mortality was noted between the two groups.

Conclusions: Patients presenting with small rAAA represent 12.2% of all rAAA and are more likely to be African American. Small rAAA is associated with similar risk of perioperative and long-term mortality compared with rupture at larger size after risk adjustment.

Keywords: Aneurysm diameter; Endovascular repair; Open surgical repair; Ruptured abdominal aortic aneurysm; Vascular Quality Initiative.