Annual rupture risk of abdominal aortic aneurysm enlargement without detectable endoleak after endovascular abdominal aortic repair.

OBJECTIVES: Whether abdominal aortic aneurysm (AAA) enlargement after endovascular aneurysm repair (EVAR), without an identifiable endoleak, is a risk factor for AAA rupture remains controversial. To our knowledge, studies including large patient numbers investigating this topic have not been done. Therefore, a considerable number of conversions to open AAA repair have been performed in this patient group. This study evaluated AAA rupture risk in patients without detectable endoleaks but with AAA enlargement after EVAR treatment.

METHODS: Baseline characteristics and follow-up data were collected prospectively by case record forms. Follow-up visits were scheduled at 1, 3, 6, 12, 18, and 24 months, and annually thereafter. The follow-up assessment included clinical examination and imaging studies. Patients were divided into three groups according to the degree of shrinkage or enlargement of the aneurysm. Group A included patients with >8 mm aneurysm shrinkage, group B consisted of patients with ≤ 8 mm shrinkage to ≤ 8 mm enlargement, and group C patients had an aneurysm enlargement of >8 mm.

RESULTS: The basis for this analysis was 6337 patients who were enrolled prospectively in the European Collaborators on Stent-Graft Techniques for Aortic Aneurysm Repair (EUROSTAR) database between 1996 and 2006. Group A included 691 patients; group B, 5307 patients; and group C, 339 patients. Ruptures occurred in 3 patients in group A, in 14 patients in group B, and in 9 patients in group C. The annual rate of rupture in group C was <1% in the first 4 years but accelerated to 7.5% up to 13.6% in the years thereafter. The mortality rate of elective conversion to open AAA repair was 6.0%.

CONCLUSIONS: The risk of rupture in patients with an AAA enlargement of 8 mm after EVAR, without detectable endoleaks, is <1% in the first 4 years. No ruptures were seen in patients with AAA enlargement without detectable endoleaks who were not treated with Vanguard stent grafts (Boston Scientific Corp, Natick, Mass) and had AAA diameters <70 mm. For this group, conversion to open repair might not be mandatory, and regular follow-up can be advised instead. After 4 years of follow-up, this study observed an increased annual rupture risk, which might indicate the need for conversion; however, groups are small, and follow-up bias could play a role.