A case-matched validation study of anatomic severity grade score in predicting reinterventions after endovascular aortic aneurysm repair

Abstract

In 2002, the Society for Vascular Surgery created the anatomic severity grading (ASG) score to classify abdominal aortic aneurysms (AAAs). Our objective was to identify the predictive capability and cutoff value of preoperative ASG score for reintervention after endovascular aneurysm repair (EVAR). We completed a retrospective review of AAA patients treated with elective EVAR from 2007 through 2011. Patients who had reinterventions as well as preoperative M2S (M2S Inc, West Lebanon, NH) three-dimensional reconstructions were identified and compared with a case-matched control group of patients without reintervention. ASG component scores (neck, aortic, and iliac) and total ASG scores were calculated using M2S software. Of the 623 patients treated with EVAR, 79 (13%) had reinterventions of which 45 had preoperative M2S three-dimensional reconstructions available for ASG score calculation. The reintervention group (mean age, 74 ± 8; 80% male) had a mean ASG score of 18 ± 5 (range, 8-30) compared with a cohort of 45 EVAR patients (mean age, 74 ± 7; 80% male) who had a mean ASG score of 13 ± 4 (range, 6-21; P < .0001). The mean AAA diameter for all patients was 52 mm ± 14 and was not significantly different between the groups. After area under the receiver-operating curve analysis, an ASG score of 17 was highly predictive for reintervention (area = 0.8; sensitivity = 60%; specificity = 78%; positive predictive value = 73%; negative predictive value = 66%). An ASG score of 13 was highly predictive for freedom from reintervention (sensitivity = 93%; specificity = 47%; positive predictive value = 64%; negative predictive value = 88%). The lowest ASG score that yielded a 100% reintervention rate was 22. The majority of reinterventions fell into three categories: proximal extension cuff (n = 18; 40%), distal extension limb (n = 7; 16%), and type II endoleak embolization (n = 13; 29%). Those that received proximal extensions had significantly higher mean total ASG score (19 vs 15; P = .0005), mean neck score (3.28 vs 2.36; P = .047), and mean aorta score (7.39 vs 2.36; P = .004). Those that received distal extensions had a significantly higher mean iliac score (9.00 vs 6.86; P = .013), and those that required an embolization had a significantly higher mean aorta branch score (1.92 vs 1.19; P = .017). Preoperative total ASG score strongly predicts reintervention after EVAR. Use of a cutoff ASG value predictive of prohibitive reintervention rates could help guide the decision between endovascular vs open AAA repair.