Purpose: To study midterm changes in aortic aneurysm morphology after endovascular aneurysm repair.
Methods: Of 94 patients with abdominal aortic aneurysms (AAAs) treated with endografts between November 1993 and August 1998, 84 were available for follow-up. Patients were evaluated preoperatively by spiral computed tomography (CT) and aortography; in follow-up, spiral CT scanning was performed at 1, 3, and 6 months and semiannually thereafter. Measurements of the aneurysm neck diameter, maximum aneurysm diameter, and the distance from the lowermost renal artery to the aortic bifurcation were made preoperatively and in follow-up.
Results: Mean follow-up was 17.5 +/- 1.1 months; 56 (67%) patients were followed for 1 year and 28 (33%) for > or = 2 years. There was a median 2-mm increase (interquartile range [IQR] 0 to 3) in neck diameter at 18 months. However, a > or = 3-mm increase was seen in 18 (46%) of 39 patients examined at 18 months (median 4 mm, IQR 3 to 4, p = 0.0001). The maximum AAA diameter decreased by 9 mm (IQR 4 to 16, p = 0.0003) at 24 months, but after 18 months, no further interval decrease was seen. Aneurysms with a persistent endoleak showed either increasing or unchanged AAA diameters. There was no change in the renal artery to bifurcation distance.
Conclusions: The infrarenal aortic neck appears to dilate after AAA endografting, but only in a subset of patients. Shrinkage of aneurysms after successful stent-grafting seems to stop after 18 months, implying that the only indication of late failure in the absence of endoleak might be aneurysm enlargement. Graft-related endoleaks are often associated with an increase in aneurysm diameter.