Midterm changes in iliac limb apposition after endovascular aortic aneurysm repair

BACKGROUND: Literature is scarce on the course of iliac endograft limb apposition after endovascular aortic aneurysm repair (EVAR), which is why this study was conducted. METHODS: A retrospective observational imaging study was performed to measure iliac apposition of endograft limbs on the first post-EVAR computed tomography angiography (CTA) scan and on the latest available follow-up CTA scan. With center lumen line reconstructions and CT-applied dedicated software, the shortest apposition length (SAL) of the endograft limbs was assessed as well as the distance between the end of the fabric and the proximal border of the internal iliac artery or the endograft-internal artery distance (EID). RESULTS: Ninety-two iliac endograft limbs were eligible for measurements, with a median follow-up of 3.3 years. At the first post-EVAR CTA, the mean SAL was 31.9±15.6 mm, and the mean EID was 19.5±11.8. At the last follow-up CTA, there was a significant decrease in apposition of 10.5±14.1 mm (P<0.001) and a significant increase in EID of 5.3±9.5 mm (P<0.001). A type Ib endoleak developed in three patients due to a reduced SAL. The apposition was <10 mm in 24% of limbs at the last follow-up vs. 3% at the first post-EVAR CTA. CONCLUSIONS: This retrospective study documented a significant decrease in post-EVAR iliac apposition over time, partly due to retraction of iliac endograft limbs at mid-term CTA follow-up. Further research is required to identify whether regular determination of iliac apposition may predict and prevent type IB endoleaks.