Abstract 459: Surgery for Small Asymptomatic Abdominal Aortic Aneurysms

Abstract

Background: Treatment of asymptomatic abdominal aortic aneurysms (AAAs) heavily depends on the size of the aneurysm. Large asymptomatic AAAs (diameter >5.5cm) are usually repaired surgically; very small AAAs (diameter <4.0cm) are monitored. Debate continues over the appropriate management for AAAs of 4.0-5.5cm diameter. Methods: The Cochrane Specialised Register and the CENTRAL databases were searched for randomized controlled trials in which patients with asymptomatic AAAs of 4.0-5.5cm were randomized to immediate repair or imaging-based surveillance at least every 6months. Outcomes had to include mortality/survival. Data were independently extracted by three researchers and were cross-checked. Results: Four trials (3314 patients) fulfilled the inclusion criteria. Two trials compared surveillance with early open repair and two trials compared surveillance with early endovascular repair (EVAR). The four trials showed an early survival benefit in the surveillance group (due to 30-day surgery operative mortality) but no significant differences in long-term survival (HR=0.88; 95%CI: 0.75, 1.02, mean follow up [FUP] 10yrs; HR=1.21, 95%CI: 0.95, 1.54, mean FUP 4.9yrs; HR=0.76, 95%CI: 0.30, 1.93, mean FUP 3yrs; HR=1.01, 95%CI: 0.49, 2.07, mean FUP 20months). A pooled analysis of patient-level data from two trials (6yrs FUP) showed no statistically significant survival difference between early open repair and surveillance (propensity-score adjusted HR=0.99; 95%CI: 0.83, 1.18), and that this lack of treatment effect did not vary by AAA diameter (P=0.39) or patient age (P=0.61). The meta-analysis of mortality at one year for EVAR trials likewise showed no significant association (RR at one year 1.15, 95%CI: 0.60, 2.17). Conclusions: The results from the four trials to date demonstrate no advantage to early repair for small AAA, regardless of whether open repair or EVAR is used and, at least for open repair, regardless of patient age and AAA diameter.