Abdominal Aortic Aneurysm Anatomic Severity Grading Score: Identifying Anatomic Attributes That Best Predict Endovascular Aneurysm Repair Outcomes

Abstract

The Society for Vascular Surgery anatomic severity grading (ASG) score is a classification system for abdominal aortic aneurysms (AAAs) stratifying candidates for endovascular aneurysm repair (EVAR). Our objective was to determine the predictive capability of total ASG score, subscores, and individual attributes for implant-related complications, endoleak, and reinterventions. Patients who underwent EVAR between 2009 and 2012 with M2S (West Lebanon, NH) three-dimensional computed tomography reconstructions were retrospectively reviewed. ASG scores were calculated from morphologic measurements by two blinded observers. Twenty-five attributes compose subscores for aortic neck, AAA, iliac arteries, and total ASG score. We identified 100 patients with mean ASG score of 18.6 ± 4.5 (range, 7.5-29). Mean AAA diameter was 54 ± 10 mm. Mean follow-up was 3.93 ± 2.5 years. Interobserver variability was determined using intraclass correlation coefficient, reflecting degree of correlation and agreement. Inter-rater agreement was good to excellent for total ASG score calculations (intraclass correlation coefficient, 0.86; 95% confidence interval, 0.70-0.92). Area under the receiver operating curve (AUROC) analysis was performed to study outcomes. Total ASG score was not a significant predictor of any outcomes. A neck subscore of ≥3 was highly predictive for type IA endoleak (AUROC, 0.82; P = .005; 95% confidence interval, 0.71-0.93) and aneurysm enlargement (AUROC, 0.71; P = .003). AAA tortuosity predicted 30-day reinterventions (AUROC, 0.84; P = .02). Iliac calcification predicted 30-day reinterventions (AUROC, 0.84; P = .021) and 30-day implant complications (AUROC, 0.8; P =. 027). The AAA and iliac subscores did not correlate with any significant outcomes. Total ASG score consists of several subscores and attributes, not all of which predict outcomes. The aortic neck subscore was predictive of type IA endoleak and sac enlargement; AAA tortuosity and iliac calcification predicted 30-day reinterventions or 30-day implant complications. This study suggests that total ASG score can be simplified to reflect attributes most predictive of EVAR outcomes.