Objective: Greater population life expectancy and consistent improvement in diagnostic techniques have increased the diagnosis of abdominal aortic aneurysms (AAAs) in the elderly population. The aim was to study the natural history of small (< 55 mm) incidental AAAs in octogenarian and nonagenarian patients to assess the need for follow up and/or invasive treatment.
Methods: This was a retrospective analysis of a prospective registry. Patients ≥ 80 years old at the time of diagnosis of a < 55 mm AAA in 1988-2018 were selected. Clinical and anatomical characteristics were registered. Patients were divided in three groups: 30 - 39 mm, 40 - 49 mm, and 50 - 54 mm AAA. The outcome variables were aorto-iliac rupture, AAA reaching a surgical threshold (≥ 55 mm), and death. A descriptive statistical analysis was performed and life tables, Kaplan-Meier curves, and uni- and multivariable Cox regression were used.
Results: Three hundred and ten patients were included, 256 (82.6%) men, with mean index age of 84.5 years (standard deviation [SD] 3.5), and median follow up of 37.9 months (interquartile range [IQR] 18.2 - 65.4). Eighteen (5.8%) AAAs ruptured; four of these patients were operated on and only one survived. Sixty-two (20%) AAA reached a surgical size; eight were repaired electively, with 0% early mortality. The survival rates were 81%, 70%, and 38% at one, two, and five years. The rupture rates were 1%, 2%, and 6% and the AAAs reaching surgical threshold were 1%, 4%, and 19% for the same time periods. AAA size < 40 mm was an independent protective factor from rupture (0.13; 95% confidence interval [CI] 0.03 - 0.48), reaching surgical threshold (0.08; 95% CI 0.04 - 0.16) and death (0.63; 95% CI 0.42 - 0.95).
Conclusion: The risk of late rupture of small incidental AAA diagnosed in octogenarian and nonagenarian patients is very small, especially when the AAA is < 40 mm in diameter. In contrast, global mortality is high. Conservative management seems sensible, with strict selection of the patients who would benefit from follow up and eventual repair.
Keywords: Abdominal aortic aneurysm; Aneurysm growth; Mortality; Nonagenarian; Octogenarian; Rupture.
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