Is proximal aortic neck dilatation after endovascular aneurysm exclusion a cause for concern?

PURPOSE: The purpose of this study was to evaluate the extent and frequency of dilatation of the proximal aortic neck over time after endovascular exclusion of abdominal aortic aneurysms and the effect on the continued integrity of the repair.
METHODS: Patients enrolled in the multicenter tube and bifurcated trials of the Guidant-Endovascular Technologies Ancure endografting system and at least 1 year of follow-up were reviewed. Neck diameter measurements were obtained from computed tomography scans that were obtained with and without contrast by an independent core laboratory facility. The diameter was considered to be the minor axis of the first slice at which point at least one half of the proximal attachment frame was located. A change exceeding 2.5 mm was considered to be significant.
RESULTS: At 1 year, 13% of the patients (42/314 patients) showed evidence of proximal neck dilatation, with a mean diameter increase of 4.8 +/- 2.4 mm. The proportion of patients with dilatation increased to 21% at 2 years (48/226 patients) and 19% at 3 years (11/59 patients). The initial presence of an endoleak, the neck length, and the aneurysm size had no clear effect on the development of neck enlargement. Initial neck diameter was inversely related to and the strongest predictor of later dilatation. Graft oversizing was not an independent predictor of neck dilatation on multivariate analysis. Only one migration of the proximal attachment system was observed during follow-up.
CONCLUSION: Most proximal aortic necks remain stable, but approximately 20% of necks increase in diameter by 2 years. Smaller necks dilate more often than larger ones. This effect is independent from the frequent oversizing of grafts in smaller necks. The integrity of the repair remains good at 3 years of follow-up.