Risk factors associated with rapid growth of small abdominal aortic aneurysms

Approximately 50% of patients who have a ruptured abdominal aortic aneurysm will die. To identify those patients who may be at high risk for rupture, we determined the risk factors for the rapid expansion of the aorta.

The growth of 514 aneurysmal aortas was followed in this study. The size of each was measured by ultrasonography at 6- to 12-month intervals until a critical size was reached or a rapid expansion of the aorta occurred. Possible risk factors for rapid expansion were determined from both initial evaluation and clinical laboratory results.

The initial size varied from 2.5 cm to 6.0 cm. The expansion rate of the aorta was 0.5 cm/yr or less in 401 patients (78%), between 0.5 and 1.0 cm/year in 50 patients (10%), and 1.0 cm/year or more (rapid expansion) in 63 patients (12%). Elective repair of aneurysms was done before rupture. Multivariate analysis indicated that the risk factors associated (p < 0.03) with rapid expansion were advanced age, severe cardiac disease, previous stroke, and history of cigarette smoking. The incidence for rapid expansion increased (p < 0.01) in older patients with aneurysms larger than 3 cm and in younger patients with aneurysms larger than 4 cm.

Risk factors associated with rapid expansion of the aorta have been determined and may help identify the patient at high risk for rupture. Ultrasonographic surveillance should be performed more frequently in these patients to help prevent rupture.