Factors Related to Limb Occlusion After Endovascular Abdominal Aortic Aneurysm Repair (EVAR)

Background: Limb occlusion is a potentially serious consequence of endovascular abdominal aortic aneurysm (EVAR). This case-control study identifies factors that predispose to limb occlusion. Methods: A consecutive series of patients from 2 centers undergoing EVAR over an 11-year period 2007-2017 were identified retrospectively. Patient records were interrogated allowing collations of demographics, intraoperative and perioperative data and surveillance data. The preoperative computed tomography angiogram was analyzed to determine EVAR relevant anatomical data. The primary outcome was occlusion of the iliac limb of the implanted EVAR. Raw data are presented as percentages, with comparative data analyzed using Mann-Whitney U-test and binomial logistic regression. Results: A total of 787 patients (702 males; median age 78 years, range 53-94 years old) were analyzed. Fifty patients reached the primary outcome, resulting in an overall limb occlusion rate of 6.35%. Factors predictive of limb occlusion were oversizing by >10% native vessel diameter, with oversizing of >20% in 50% of those that occluded. External iliac artery landing zone (12/50 limb occlusions) 24% and postoperative kinking (5/50 limb occlusions) 10% were also more common in those that occluded. Fifty randomly selected controls with similar baseline characteristics were studied. Oversizing of the iliac endograft was found to be significantly greater in the limb occlusion group compared to the controls (P < 0.001) which remained significant on regression analysis. There was no correlation with iliac tortuosity. The Cook stent graft had a 9% limb occlusion rate across sites. Medtronic and Vascutek endografts had 2.4% and 2.5% limb occlusion rates respectively. Conclusions: Oversizing of iliac limbs by >20% could be a contributing factor to limb occlusion after EVAR and judicious oversizing should be used.