Excluder Stent Graft-Related Outcomes in Patients with Aortic Neck Anatomy Outside of Instructions For Use (IFU) within the Global Registry for Endovascular Aortic Treatment (GREAT): Mid-term Follow-Up Results.

Background: The utilisation rate of endovascular aortic aneurysm repair has increased continuously over the past 2 decades. Endovascular aortic aneurysm repair is still performed frequently in patients with an unfavourable proximal seal zone, despite the associated late complications.

Purpose: We aimed to evaluate the mid-term durability of the GORE® EXCLUDER® AAA Endoprosthesis, featuring the C3 delivery system, in patients with a proximal neck anatomy outside the instructions for use (IFU).

Methods: A retrospective sub-analysis of the Global Registry for Endovascular Aortic Treatment including patients treated for abdominal aortic aneurysms with the GORE EXCLUDER AAA Endoprosthesis (W.L. Gore & Associates, Inc, Flagstaff, Arizona) was performed. A "challenging neck" was defined as those treated outside the IFU with an aortic neck length <15 mm and/or aortic neck angle >60°. Cox proportional analyses were used to test for time-to-event differences between those treated within and outside the IFU while accounting for covariates, specifically proximal neck length and neck angle. The main outcomes assessed were 5-year all-cause mortality, 5-year endoleak development (type I or III), and 5-year device-related reinterventions.

Findings: Of the 3,324 patients included in the analysis, 411 (12.4%) had a challenging neck and 2,913 (87.6%) did not. The patients in the challenging neck group were significantly older (74.9 years vs. 73.2 years, p≤0.0001) and had a significantly larger aortic aneurysm diameter at the time of the intervention than those treated within the IFU (61.2 mm vs. 56.4 mm, P< 0.0001), shorter proximal neck length (18 mm vs. 30 mm, P< 0.0001) and larger infrarenal neck angle (60.8° vs. 25.8°, P< 0.0001). In the multivariate analysis, brachial access site and challenging neck were not independent risk factors; increased age was associated with a shorter time to mortality (hazard ratio 1.051, 95% confidence interval 1.039-1.062, P< 0.0001), as was the use of tobacco (hazard ratio 1.329, 95% confidence interval 1.124-1.571, P= 0.0009). The 5-year all-cause mortality (36.2% vs. 27.5%, P= 0.002) and aorta-related mortality (3.8% vs. 1.1%, P= 0.002) were significantly higher in the challenging neck group. The risk of death within 5 years also increased significantly at 1.1% per millimetre increase in the abdominal aortic aneurysm diameter (P= 0.0005). Furthermore, the rates of type Ia endoleak development (7% vs. 1.2%, P< 0.001) and requirement for reintervention (13.3% vs. 9.7%, P< 0.001) were higher in those treated outside the IFU (challenging neck group).

Conclusions: Treatment with the Excluder AAA Endograft outside the IFU was associated with higher 5-year mortality values, increased type Ia endoleak development rates, and a greater need for reintervention compared with treatment within the IFU. This reiterates that fenestrated and open treatments should be strongly considered in cases with aortic neck anatomies outside the IFU. Infrarenal endovascular intervention outside the IFU should only be used when there is no alternative, with meticulous procedural planning and intervention to promote satisfactory outcomes.