Global Iliac Branch Study: Image-based Detailed Anatomic Assessment and Device Performance

Abstract

Iliac branch devices are designed to preserve patency of the internal iliac artery for endovascular repair of aortoiliac aneurysms. The Global Iliac Branch Study (NCT05607277) is an international, multicenter, retrospective study of over 300 iliac branch devices with diverse use. The objective of this project was to evaluate potential anatomic determinants of adverse iliac events. Patients were included if they had both pre- and post-treatment computed tomography imaging available after implantation of a bifurcated device. Morphologic measurements included arterial diameters, stenosis, calcification, aortic and iliac bifurcation angles, and tortuosity indices (Fig), performed by a core laboratory with a standardized and validated protocol. Adverse iliac events were defined as type I or III endoleak, occlusion, device constriction (due to either narrow anatomy or another component), or clinical events requiring reintervention of the ipsilateral iliac branch system. This abstract is based on univariate analysis. Paired t test was used to compare tortuosity indices and splay angles pre- and post-treatment. Logistic regression was used to assess associations between anatomic measurements and adverse iliac events. Analysis was performed by iliac system (ie, bilaterally treated patients’ right and left sides were analyzed independently). We analyzed 297 subjects (286 males, 11 females) with 331 iliac branch devices (104 nitinol, 227 stainless steel). Mean clinical follow-up was 3.8 years. Mean baseline total iliac artery index was 1.47 (range, 1.44 to 1.50), mean baseline common iliac artery index was 1.10 (range, 1.09 to 1.12). Changes in iliac artery tortuosity indices and aortic and iliac splay angles are reported in Table. Anatomy is significantly straightened with treatment in all devices. There were 54 adverse iliac events in 44 systems, requiring 35 reinterventions (median time to reintervention, 41 days; range, 0 days to 6.2 years). There were 18 endoleaks (17 type I, 1 type III), 29 occlusions, and five device constrictions. In nitinol devices, diameter of the internal iliac landing zone <10 mm and non-conformability (reduction in total iliac index beyond 15%) were associated with adverse iliac events (odds ratio [OR], 14; P = .016 and OR, 7.8; P = .021, respectively.) In the stainless steel devices, no significant univariate associations were found with anatomic measurements. These results suggest that purpose-built iliac branch devices are highly efficacious in treating tortuous iliac anatomy, with a high patency rate and low reintervention rate. Some anatomic factors are strongly predictive of adverse iliac events in nitinol devices.TableChanges in iliac artery tortuosity indices and splay anglesPre-treatment [95% CI]Post-treatment [95% CI]P-valueAll iliac branch systems (n = 331) Total iliac artery index1.47 [1.44-1.50]1.31 [1.28-1.33]<.0001 Common iliac artery index1.10 [1.09-1.12]1.04 [1.03-1.04]<.0001 Aortic splay angle58.3 [56.2-60.5]41.4 [39.6-43.1]<.0001 Iliac branch splay angle52.3 [49.7-54.8]47.4 [45.3-49.6]<.0001Nitinol iliac branch systems (n = 104) Total iliac artery index1.53 [1.47-1.60]1.44 [1.38-1.50]<.0001 Common iliac artery index1.13 [1.10-1.16]1.06 [1.05-1.08]<.0001 Aortic splay angle56.4 [52.1-60.8]45.3 [42.3-48.3]<.0001 Iliac branch splay angle48.0 [43.5-52.5]44.5 [40.7-48.3].0633Stainless steel iliac branch systems (n = 227) Total iliac artery index1.44 [1.42-1.47]1.25 [1.23-1.26]<.0001 Common iliac artery index1.09 [1.07-1.10]1.03 [1.02-1.03]<.0001 Aortic splay angle59.2 [56.8-61.7]39.6 [37.5-41.7]<.0001 Iliac branch splay angle54.2 [51.1-57.3]48.8 [46.2-51.4]<.0001CI, Confidence interval. Open table in a new tab