Global Iliac Branch Study (Iliac Conformability Paper, Gore vs. Cook)

Background and significance Abdominal aortic aneurysms (AAAs) affect 0.5% to 1.3% of women and 4.0% to 7.6% of men age 65 and older1-4. Infrarenal AAAs frequently extend distally through the aortic bifurcation and into the common, external, and/or internal iliac arteries,5,6 presenting a challenge for aneurysm repair. Current guidelines prioritize repair strategies which preserve blood flow to the internal iliac artery (IIA) with the goal of reducing the complications of buttock claudication and pelvic ischemia.7-9 As endovascular intervention has become standard practice for those with eligible anatomy, 7 branched endovascular devices have been developed to preserve IIA blood flow when repairing AAAs with iliac involvement.

With the ongoing development of devices and techniques, the range of iliac anatomy eligible for endovascular repair has increased. Most notably, multiple iliac branch devices (IBDs) are being used to treat AAAs involving highly tortuous iliac arteries. A variety of IBDs are available globally, and as such, there is an opportunity to determine if certain anatomic factors- specifically tortuous and non-conformable iliac arteries- may predict device complications.

To begin exploring this question, the Global Iliac Branch Study (GIBS)- a partnership between 5 centers across the United States, Europe, and Asia- was developed to evaluate performance of branched endografts based on anatomical assessments, with analysis of CT scans using centralized and standardized analysis protocols at the AortaCore Imaging Lab at the University of Wisconsin-Madison.

Previous work In addition to elevated risk of conversion to open repair,10 iliac tortuosity has previously been associated with increased risk of "conformability" events, including seal zone failure, type III endoleak, occlusion, stenosis, compression, and device migration.11-13

Previously, the applicant and her faculty mentor have explored the interaction between iliac tortuosity and device conformability in patients treated with the W.L.GORE EXCLUDER iliac branch endoprosthesis (IBE).14 Non-conformation was defined as a decrease in the total iliac index of tortuosity beyond 15%. This study found that non-conformation, as well as internal iliac artery diameter of less than 10 mm, were associated with adverse iliac events after iliac branch endoprosthesis (odds ratio, 8.2 [P = .02] and odds ratio, 12.3 [P = .02], respectively).