Global Iliac Branch Study (GIBS)

April 18, 2024 updated by: University of Wisconsin, Madison

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

This project seeks to determine if certain anatomic factors, specifically tortuous and non-conformable iliac arteries, may predict device complications, including seal zone failure, type III endoleak, and occlusion. Approximately 400 subjects from 5 academic centers across the United States, Europe, and Asia will be included in this study. Various markers of pre- and post-treatment iliac anatomy will be measured using CT imaging, and clinical events will be reported by academic centers. The relationship of imaging data to patient demographics will then be assessed alongside anatomic and demographic predictors of non-conformability.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

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).

Similar to the aforementioned studies demonstrating increasing ranges of anatomic eligibility with the development of more complex and accommodating devices, the applicant and her mentor explored device eligibility for endovascular repair (EVAR) of small AAA over two years in a paper published in November 2021 in the Journal of Vascular Surgery which found high levels of anatomic eligibility for EVAR at baseline, and preservation of this eligibility over two years.15 These findings, like those previously mentioned, suggested that advancements in EVAR device design have improved anatomic eligibility for the procedure. Compared to open repair, EVAR is associated with decreased periprocedural morbidity and hospital length of stay,16 and as such is the preferred approach, as well as a major target for innovation in the field of vascular surgery.

Methods and analysis CT images of 400 subjects with IBDs from 5 centers around the globe will be transferred and analyzed at the University of Wisconsin-Madison AortaCore Imaging Lab under an Institutional Review Board (IRB) approved protocol. Post-processing workstations using Aquarius Intuition (version 4.4.12, TeraRecon) will be used to measure morphology data. Each CT will be fit with a manually corrected centerline that is equidistant from the outer walls of the aneurysmal vessels. Measurements will be completed at both the pre-treatment and post-treatment intervals; these include common, external, and internal iliac artery diameters and lengths, common iliac artery index of tortuosity (Common Iliac Index; Centerline length of the common iliac artery (CIA) divided by the shortest straight-line distance between the CIA origin and iliac bifurcation), total iliac artery index of tortuosity (Total Iliac Index; centerline length of the CIA plus centerline length of the external iliac artery, divided by the shortest straight-line distance between the CIA origin and terminal external iliac artery), and presence of the double iliac sign (when any portion of the iliac vessel is tortuous enough to be duplicated in a single cut of an axial computed tomography slice.)17 Figures 1 and 2 demonstrate these measurement techniques for capturing and quantifying tortuosity.

Measurement of these values before and after device deployment allows the determination of differences in iliac artery length pre- and post-treatment, which is used to quantify device "conformability."18 Notably, devices which produce minimal changes to native anatomy are considered more "conformable" and devices that make greater changes to iliac lengths and angle anatomy are considered "non-conformable" (Figure 3.)

In addition to pre-treatment demographics and comorbidities, including age, sex, and geographic origin, associations between iliac tortuosity indices and the aforementioned CT measurements will be determined in relation to clinical events collected by each center including conversion to open repair, re-intervention, endoleak, occlusion, compression, patient-reported symptoms and adverse events, and death.

Continuous variables will be compared using the unpaired Student t test if normally distributed and the Mann-Whitney U test or Wilcoxon matched pairs test if they are not normally distributed. Categorical variables will be compared using the Fisher exact test or Pearson's x2 test.

Expected outcomes As previously described, in preliminary data14 we have identified that a postoperative change in iliac tortuosity ("non-conformability") predicts adverse events in a sample size of 98 patients. We hypothesize that a larger sample size of 400 patients will confirm this relationship between non-conformability and adverse events, and enable identification of pre-operative predictors of non-conformability. Furthermore, we anticipate that the inclusion of a more diverse selection of endovascular devices will more broadly capture the relationship between device conformability and iliac tortuosity beyond what can be determined based on commercially available devices in the United States.

Study Type

Observational

Enrollment (Actual)

297

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Wisconsin
      • Madison, Wisconsin, United States, 53792
        • University of Wisconsin

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

17 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

400 subjects with Endovascular repair with Iliac Branched Devices for treatment of abdominal aortic aneurysm with iliac involvement.

Description

Inclusion Criteria:

  • Subjects who have undergone endovascular aortic repair of AAA with iliac involvement via iliac branch device.

Exclusion Criteria:

  • None

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Case-Only
  • Time Perspectives: Retrospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Device conformability in relation to endovascular repair of abdominal aortoiliac aneurysms.
Time Frame: Pre-treatment
Adverse events: any radiographic or clinical ipsilateral complication, i.e. dissection, kink, compression, occlusion, endoleaks.
Pre-treatment
Device conformability in relation to endovascular repair of abdominal aortoiliac aneurysms.
Time Frame: 1 day at First post-operative imaging appointment
Adverse events: any radiographic or clinical ipsilateral complication, i.e. dissection, kink, compression, occlusion, endoleaks.
1 day at First post-operative imaging appointment

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Wisconsin, Madison

Investigators

  • Principal Investigator: Jon Matsumura, MD, University of Wisconsin, Madison

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 1, 2014

Primary Completion (Actual)

December 1, 2020

Study Completion (Actual)

June 1, 2021

Study Registration Dates

First Submitted

October 26, 2022

First Submitted That Met QC Criteria

November 4, 2022

First Posted (Actual)

November 7, 2022

Study Record Updates

Last Update Posted (Actual)

April 19, 2024

Last Update Submitted That Met QC Criteria

April 18, 2024

Last Verified

October 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2020-0677
  • Protocol Version 7/29/2020 (Other Identifier: UW Madison)
  • A539750 (Other Identifier: UW Madison)
  • SMPH/SURGERY/VASCULAR SURGERY (Other Identifier: UW Madison)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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