# Conformable Endovascular Aneurysm Repair (EVAR) Stability in Hostile Neck Abdominal Aortic Aneurysms: A Single-Center Experience

## TL;DR

This study evaluates the early stability of a conformable stent graft in treating abdominal aortic aneurysms with challenging neck anatomy, finding minimal migration over one year.

## Contribution

The study provides empirical evidence on the early performance of the CLEVAR device in hostile neck aneurysms, highlighting its stability and potential clinical benefits.

## Key findings

- The CLEVAR device showed minimal mean migration of 1.29 mm in hostile neck abdominal aortic aneurysms over one year.
- Migration was symmetrical between right and left renal reference points with no significant difference.
- Stent displacement was statistically significant but remained below clinically relevant thresholds.

## Abstract

Background

Stent graft migration is a well-recognized complication of endovascular aneurysm repair (EVAR) that can predispose patients to type I endoleaks, renal artery compromise, and secondary interventions, particularly in cases with hostile neck anatomy, which poses a significant technical challenge for graft fixation. The GORE Excluder Conformable AAA Endoprosthesis (CLEVAR) is specifically designed to address these challenges by accommodating neck lengths as short as 10 mm, diameters down to 16 mm, and angulations up to 90°. This study aimed to evaluate the early stability and safety of the CLEVAR in patients with hostile neck anatomy by assessing its migration behavior within the first postoperative year.

Methodology

This retrospective, single-center study analyzed consecutive patients who underwent repair of hostile neck abdominal aortic aneurysms with the CLEVAR device between January 2019 and December 2022, focusing on early (≤1 year) postoperative stability. Eligible patients completed both three-month and one-year postoperative CT angiography. Migration was assessed by measuring the distance between the proximal stent edge and the bilateral renal arteries at both time points, with the difference representing stent movement. Descriptive statistics were calculated, normality was tested using the Shapiro-Wilk method, and comparisons were performed with nonparametric Wilcoxon signed-rank tests.

Results

A total of 25 patients were included. The mean stent migration across the cohort was 1.29 mm (SD 1.36 mm), with a median of 0.85 mm and a maximum migration of 6.0 mm. Both right and left renal reference points showed similar results (mean 1.17 mm and 1.40 mm, respectively), with no statistically significant difference between sides (p = 0.4261). Migration distributions were non-normally distributed and positively skewed. Analysis confirmed that stent displacement was statistically greater than zero (p < 0.00000001), indicating measurable, albeit small, positional changes during the interval.

Conclusions

In this study, the CLEVAR device demonstrated stable proximal fixation in challenging hostile neck anatomies over the first postoperative year. Observed migration was minimal, symmetrical, and well below thresholds considered clinically significant. These findings suggest that CLEVAR provides reliable early stability in anatomically complex aneurysm necks, potentially reducing the risk of migration-associated complications. However, the small sample size, retrospective design, and one-year follow-up limit generalizability. Longer-term studies with larger cohorts are needed to confirm the durability of fixation and explore the relationship between late migration, endoleak incidence, and the need for reintervention.