Impact of Age and Intraluminal Thrombus Volume on Abdominal Aortic Aneurysm Sac Enlargement after Endovascular Repair

Background: Abdominal aneurysmal sac enlargement after endovascular aortic repair (EVAR) is a critical issue. However, the predictors have not yet been fully determined. Although unrecognized, intraluminal thrombus volume (ITV) is an important index. Therefore, we retrospectively evaluated the correlation among preoperative ITV, residual type II endoleak, and sac enlargement after EVAR, based on the long-term follow-up. Methods: Between 2006 and 2011, 151 consecutive patients underwent EVAR at a single cardiovascular institute. Emergency surgery was performed on 7 patients (4.7%). Of 148 patients excluding 3 patients with residual type I endoleak, sac enlargement (>= 5 mm progression) after EVAR was observed in 24 patients (16.2%) and 8 patients required reintervention. The mean follow-up period was 2.4 +/- 1.4 years. The outer volume and enhanced luminal volume were calculated from enhanced 1-mm slice computed tomography, and the difference was defined as ITV. Results: Age (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.04-1.20, P = 0.0007), outer volume (HR 1.04, 95% CI 1.01-1.07, P = 0.0118), percentage of ITV (HR 0.90, 95% CI 0.84-0.96, P =.0027), and type II endoleak (HR 10.15, 95% CI 3.55-31.10, P < 0.0001) were isolated as predictors of sac enlargement by multivariate analysis. Also, patent inferior mesenteric artery (odds ratio [OR] 4.45, 95% CI 1.38-20.07, P = 0.0105) and percentage of ITV < 30.1% (OR 3.52, 95% CI 1.32-10.30, P = 0.0112) were detected as independent risk factors for residual type II endoleaks. Additionally, in patients without endoleak, patient age (>= 83 years) was an independent risk factor for sac enlargement after EVAR (P = 0.0056). Conclusion: Age and ITV percentage had significantly great impact on sac enlargement and type II endoleak after EVAR.