Iliac Artery Tortuosity, Calcification and Abnormal Shape Augment Aortic Aneurysm Anatomy in Predicting Complications After Endovascular Aneurysm Repair

Post-surgical complications following endovascular aneurysm repair (EVAR) remain a risk, arising from technical difficulties imposed by highly calcified or tortuous iliac arteries. Automated methods enable segmentation of the iliac artery to potentially better define perioperative risk prediction. This study uses imaging software to characterise segmental iliac artery anatomy and aims to establish if iliac artery abnormalities can predict adverse outcomes following EVAR. Pre-operative clinical information and CT angiograms were obtained from 189 patients who underwent elective EVAR. Patients were followed for up to 3 years to detect stent-related complications and mortality. Aneurysm morphology was manually measured on CT scans. Automated measurements of vessel shape, curvature and calcification were taken for multiple subdivisions of the common and external iliac arteries. Logistic regression models were trained to assess the influence of iliac artery and aneurysm morphology on outcomes. Combining iliac and aortic features improved predictions of both stent-related complications and morbidity over using either alone. Models predicting death and both early and late stent complications had respective areas under the curve (AUCs) of 0.761, 0.935 and 0.833. Iliac artery calcification and curvature were significant predictors of poor outcomes. Automated morphological assessment of the common and external iliac artery improves the prediction of complications following EVAR. The improved power of iliac morphology to predict late complications and death implies that regional abnormalities of the iliac arteries are important when assessing surgical risk. This allows further rationalisation of the selection of individuals for treatment and may improve patient outcomes.