Preoperative Thrombus Volume Predicts Sac Regression after Endovascular Aneurysm Repair

Purpose: To examine whether preoperative aneurysm thrombus volume correlated with abdominal aortic aneurysm (AAA) sac regression following endovascular aneurysm repair (EVAR). Methods: Clinical records and computed tomographic angiograms (CTAs) from patients undergoing EVAR from 2003 to 2008 were reviewed. Inclusion criteria for this study were available preoperative CTA images, ≥12-month follow-up with surveillance imaging, lack of re-intervention at 12 months, and treatment with commercially available devices. Patients with ruptured AAAs, those requiring an aortomonoiliac stent-graft, and clinical trial cases were excluded. Based on these criteria, satisfactory images and clinical follow-up were available in 100 patients (90 men; mean age 76.8 years, range 55–95). Preoperative CTAs were categorized as demonstrating “minimal,” “moderate,” or “severe” aneurysm thrombus load by 2 independent examiners blinded to clinical outcome. Percentage of the aortic cross-sectional area occluded by clot (% clot area) was calculated as [(total area) – (luminal area)]/(total area). Multivariate logistic regression analysis was performed to determine predictors of sac shrinkage at long-term follow-up. Results: AAA thrombus was classified as minimal in 24%, moderate in 23%, and severe in 53%. Thrombus area averaged 11%±13%, 41%±14%, and 72±12% in each group, respectively. By multivariate analysis, minimal thrombus (OR=1.47) and greater AAA diameter (OR=1.3) were independent predictors of sac regression at 1, 6, and 12 months (all p