Cook Zenith Alpha Endograft: A Protocol to Minimise Limb Graft Occlusion

Objective: Numerous articles have reported an increased incidence of limb graft occlusion (LGO) with the Cook Zenith Alpha endograft compared with other endografts in endovascular aortic aneurysm repair (EVAR). The present study aimed to assess the rate of LGO after EVAR in particular with the Cook Zenith Alpha device when adhering to a standardised protocol designed to prevent limb related complications. Methods: This was a non-sponsored retrospective study performed in two university vascular surgery centres employing the same protocol for limb complication prevention during EVAR from 2016 to 2019. The protocol encompassed: (1) angioplasty of any common or external iliac artery with > 50% stenosis before endograft navigation; (2) proximal sealing zone of limbs at the same level of the flow divider with minimum overlap, which is more restrictive than the Cook Zenith Alpha instructions for use; (3) semi-compliant kissing ballooning of limbs; (4) limb stenting for any residual tortuosity, kinking, or stenosis; and (5) adjunctive common and external iliac stenting for residual stenosis or dissection after EVAR. Patients enrolled in this study were treated with standard aortobi-iliac EVAR. Follow up was performed by clinical visit and duplex ultrasonography at discharge, six months, and yearly thereafter. The primary endpoint was to evaluate the LGO rate with different EVAR devices (Cook Zenith Alpha, Gore C3, and Medtronic Endurant) and to determine potential risk factors for LGO associated with the Zenith Alpha. Results: In the study period, 547 EVARs were considered: 233 (42.6%) Cook Zenith Alpha, 196 (35.8%) Gore Excluder, and 118 (21.6%) Medtronic Endurant. The mean follow up was 44 ± 23 months, and the five year freedom from LGO was 97 ± 3%, without differences between groups (97 ± 2%, 95 ± 3%, and 100% with Cook Zenith Alpha, Medtronic Endurant, and Gore Excluder, respectively; p = .080). In the Zenith Alpha group, intra-operative adjunctive iliac artery angioplasty, iliac artery stenting, or iliac limb stenting was performed in 8%, 3.4%, and 9.7% of cases, respectively. Analysis of potential risk factors for LGO identified external iliac artery distal landing and large main bodies (ZIMB 32 – 36) to be independently associated with LGO during follow up (hazard ratio [HR] 18, 95% confidence interval [CI] 3 – 130, p = .004; and HR 12, 95% CI 1.2 – 130, p = .030, respectively). Conclusion: The present experience with a protocol for limb complication prevention allows achievement of a low rate of LGO at five years with Zenith Alpha endografts similar to other endografts. Specific risk factors for the Cook Zenith Alpha endograft are external iliac artery distal landing and the use of a large main body (ZIMB 32 – 36).