Late Survival in Nonoperated Patients with Infrarenal Abdominal Aortic Aneurysm

Objective/Background Historical studies report high rupture rates in patients with nonoperated abdominal aortic aneurysms (AAAs) of > 5.5 cm diameter, although a recent audit has questioned this. Methods This was a retrospective review of 138/764 (18%) patients with AAAs evaluated in a preassessment anaesthetic clinic (PAC) between 2006 and 2012, who either did not undergo elective AAA repair or who underwent deferred repair. The remaining 626 underwent repair. Patients with severe comorbidities (dementia, advanced malignancy, life-expectancy < 1 year) and not referred to PAC were excluded. Results At a median of 27 months, 71 (52%) died, 36 (51%) following rupture. Cumulative survival, free from rupture or surgery for acute symptoms, was 96% at 1 year, 84% at 3 years, and 64% at 5 years, where baseline AAA diameters were 5.5–6.9 cm. For diameters ≥ 7 cm, survival, free from rupture, was 65% at 1 year, 29% at 3 years, and 0% at 5 years. Median interval to rupture was 47 months (AAA diameter 5.5–6.9 cm) and 21 months where baseline diameters were ≥ 7 cm. Rupture accounted for 32% of late deaths in patients with AAAs of 5.5–5.9 cm diameter, 46% in those with AAAs measuring 6.0–6.9 cm in diameter, and 71% in patients with AAA measuring ≥ 7 cm in diameter. Conclusion Approximately half of all late deaths in this nonoperated cohort were not AAA related, suggesting that even had repair been undertaken, it would not have prolonged patient survival. The incidence of rupture in “high-risk” patients with an AAA < 7 cm diameter was < 5% at 1 year, thereby giving ample time to optimise risk factors and improve pre-existing medical conditions prior to undertaking a deferred intervention. Even if these patients did not undergo surgical repair, the risk of late rupture was relatively low. By contrast, nonoperated patients with AAAs ≥ 7 cm in diameter face a very high risk of rupture and will probably benefit from elective surgery, with the caveat that a higher procedural risk might have to be incurred.