Anatomical features of aneurysm sac, thrombus volume and localization and their impact on post-EVAR outcomes

Endovascular Aortic Repair (EVAR) is widely used to treat abdominal aortic aneurysms. However, long-term success depends on aneurysm sac remodeling, which is influenced by endovascular complications like endoleak. This study investigates the relationship between thrombus localization, IMA diameter and the number of patent lumbar arteries with type 2 endoleak and sac shrinkage.

A total of 143 patients who underwent elective EVAR were included in the analysis. Preoperative and postoperative thrombus volume and localization were assessed, IMA diameter and lumbar artery counts were evaluated. Thrombus was categorized as either anterior, posterior, circular, or absent.

Within this 143 patients, a postoperative volume reduction of ≥10% was observed in 44 patients. In 65 patients, the thrombus was circularly located whereas 11 patients had posteriorly localized thrombus formation. Posterior thrombus localization was associated with an approximately 7% reduction in aneurysm sac volume during follow-up. In contrast, circular thrombus localization was associated with less sac shrinkage and a higher number of patent lumbar arteries, which likely impeded effective remodeling. The presence of more than three patent lumbar arteries (p < 0.001) were negatively correlated with sac shrinkage, suggesting an increased risk of secondary interventions.

These findings suggest that thrombus localization and lumbar artery count may be associated with sac remodeling outcomes after EVAR. Posterior thrombus localization was associated with more favorable sac shrinkage and fewer patent lumbar arteries, although a direct effect on secondary intervention rates was not demonstrated. These findings suggest that thrombus localization and lumbar artery burden may help identify patients at risk for less favorable sac remodeling after EVAR. Such parameters may support closer surveillance and individualized consideration of preventive strategies in selected cases, but prospective validation is required before treatment recommendations can be made.