Outcomes of original and low-permeability Gore Excluder endoprosthesis for endovascular abdominal aortic aneurysm repair

Objective

Because of concern about the percentage of enlarging abdominal aortic aneurysms (AAAs) after endovascular repair with the Excluder device (W.L. Gore & Assoc, Inc, Sunnyvale, Calif), the graft material was modified to reduce its permeability and released for commercial use in mid-2004. We studied all AAA repairs with Excluder endografts performed at our institution, including the original-permeability (OP) version (n = 99) and the low-permeability (LP) version (n = 48).

Methods

All patients were followed up with serial computed tomography (CT) angiography and three-dimensional (3D) reconstruction. Morphologic measurements, including AAA diameter and 3D volume, were prospectively entered into a database to evaluate changes in AAA size over time. Owing to the length of available follow-up for the LP version, the primary end point was AAA size change at 6 and 12 months, evaluated by Mann-Whitney U test for unpaired samples.

Results

Preoperative and postoperative anatomy was similar in the two groups, including AAA diameter (OP, 5.6 ± 1 cm; LP, 5.8 ± 2 cm; P = .3), aortic neck length (OP, 21 ± 1 mm; LP, 22 ± 2 mm; P = .9), postoperative aortic seal zone (OP, 18 ± 1 mm; LP, 16 ± 1 mm, P > .1) and iliac seal zone (OP, 33 ± 1 mm, LP 31 ± 1 mm, P = .2). The rate of sac shrinkage differed significantly. Orthogonal diameter measurements showed a significant difference in the rate of shrinkage by 12 months postoperatively (OP, −2.1 ± 1 mm; LP, −5.1 ± 1 mm; P = .01). By 3D volume, the rate of shrinkage was considerably different between the two groups at both 6 and 12 months (12 months: OP, −6% ± 1%; LP, −20 ± 4%; P = .0006). There was no enlargement by diameter in either group at 6 or 12 months postoperative. By standard volume criteria, however, 12 of 99 patients in the OP group and one of 48 patients in the LP group had significant AAA enlargement ≤12 months (P = .04). Of these, four of 12 patients in the OP group had enlargement without apparent endoleak, even on delayed-contrast CT. The remainder had persistent type II endoleaks (8/12 in the OP group and 1/1 in the LP group). Multivariate analysis revealed graft permeability (P < .0001) and endoleak (P < .0001) as independent factors in aneurysm size change. In the OP group long-term, the average AAA enlarged at later time points compared with the prior scan: 24 months, −0.2%; 36 months, +0.2%; 48 months, +2%; and 60 months, +2% (P < .0002).

Conclusions

In early follow-up, the low-permeability Excluder device is associated with a significantly greater aneurysm shrinkage rate than the original version. Clinically important enlargement also appears significantly different within 1 year of implantation. Despite these promising results, longer follow-up is needed to determine whether these differences will persist.