Asymptomatic Small AAA (4cm) Do Not Require Prophylactic Therapy

Objective: This study reports the clinical outcomes of small AAA (4cm) in a modern endovascular practice at an academic medical center.
Methods: We identified patients with small infrarenal AAA (3.8cm - 4.2cm, mean 4.07cm) undergoing continuous semiannual ultrasound surveillance. Natural history and outcomes were evaluated and included freedom from growth and freedom from intervention, using Kaplan-Meier method.
Results: 198 patients (145 men, 53 women) with small infrarenal AAA's were followed for a mean period of 44 months (range 6 - 118 months). There was one (0.5%) documented rupture. 48% did not achieve 5 cm diameter at 5 years by Kaplan-Meier (Figure 1). During the follow-up period, 31 patients (16%) underwent AAA repair due to size (5 cm for women, 5.5 cm for men), rate of expansion (>5mm/6 months) or aneurysm-related complications. In all comers, 72% and 65% of patients did not require intervention at 5 and 8 years, respectively (Figure 2).
Conclusions: Asymptomatic 4 cm infrarenal AAA follow a benign course with a low rate of rupture and a relatively slow expansion rate. The majority of patients do not require surgical intervention. The results of this study call into question a policy of universal therapy toward 4 cm infrarenal AAA.