Neck diameter and inner curve seal zone predict endograft-related complications in highly angulated necks after endovascular aneurysm repair using the Aorfix endograft.

OBJECTIVE

Many studies have found that preoperative aneurysm anatomy can determine the postoperative complication rates for endovascular aneurysm repair (EVAR). With continual improvement in endograft technology, patients with challenging anatomy are increasingly able to undergo successful treatment with EVAR. This study aimed to quantify the influence of proximal neck anatomy on contemporary outcomes in a cohort of abdominal aortic aneurysm patients with highly angulated aneurysm necks.

METHODS

The study included 205 patients originally enrolled in the Prospective Aneurysm Trial: High Angle Aorfix Bifurcated Stent Graft (PYTHAGORAS) trial, the largest study to date to enroll patients with aortic aneurysm neck angles >60 degrees. Anatomic parameters included measurements of the proximal aneurysm neck as well as seal zones modeled in preoperative computed tomography scans. Follow-up up to 5 years postoperatively was available, for which stent-related complications (defined as sac expansion, stent migration, and type Ia endoleak) were assessed. Predictive anatomic parameters were assessed by Cox regression models, and a final multivariate model was created to predict complications. The cohort was also stratified by neck diameter for further comparison of complication rates.

RESULTS

Of 205 patients enrolled in the trial, 67 stent-related complications occurred in 36 patients (17.6%) at 5 years after EVAR. Median follow-up was 48 months. Demographic and medical comorbidities did not predict risk of complications, nor did proximal neck length or neck angle. Independent predictors of post-EVAR complications included increasing proximal neck diameter (hazard ratio, 1.14; 95% confidence interval, 1.03-1.27; P < .05) and decreasing seal zone inner curve length (hazard ratio, 1.03; 95% confidence interval, 1.01-1.06; P < .05), which yielded a fair discriminatory utility (concordance, 0.67). Stratification by median neck diameter of 22.5 mm yielded two groups; patients with larger aortic necks (mean diameter, 24.8 ± 2.1 mm) had a 21.8% complication rate vs 12.6% in patients with smaller necks (mean diameter, 20.1 ± 1.6 mm; P < .05).

CONCLUSIONS

Proximal aortic neck diameter and the seal zone inner curve length were found to be the best predictors of complications related to Aorfix (Lombard Medical, Oxfordshire, United Kingdom) in this population with highly angulated neck anatomy. Modeled seal zones are better able than traditional measurements to capture the limitations of a short, angled neck. These findings may inform preoperative risk stratification and planning in patients with hostile aortic neck anatomy undergoing EVAR.