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Multicenter Study Of Aneurysm Sac Behavior After Endovascular AAA Repair With The Original And Low Permeability Gore Excluder

Mark Fillinger¹, Luke K. Marone², Mark D. Morasch.^3
1Dartmouth Hitchcock Medical Center, Lebanon, NH; ²U Pittsburgh, Pittsburgh, PA; ³Northwestern, Chicago, IL.

OBJECTIVES: To compare AAA sac behavior after endovascular repair with the original permeability (OP) Excluder and newer Low Permeability (LP) device via multicenter clinical trial.

METHODS: Data were accrued for the LP device via FDA-approved multicenter post-market surveillance study using the same anatomic inclusion criteria as the original Pivotal trial. The LP study group included 10 centers, and the enrollment target of 140 patients was reached in August 2006. The OP control group consisted of 120 patients randomly selected from the Pivotal clinical trial of the original Excluder. CT scans were evaluated with standard 2-D and 3-D measurements by an independent core lab (M2S) for both groups. For the OP group, 97 AAAs could be evaluated for size change at 6 and 12 months. For the LP group, 87 could be evaluated at 6 months, and 46 at 12 months by the Core lab to date (the study is ongoing).

RESULTS: Pre- and post-operative anatomy was similar in the two groups, including AAA diameter (OP 5.4±1 cm, LP 5.5±1 cm, p=.3), aortic neck length (OP 25±1 mm, LP 22±1 mm, p=.12), and post-op aortic seal zone (OP 18±1 mm, LP 15±1 mm, p=.08). The rate of sac shrinkage differed significantly at 12 months post-op for diameter (OP -1.2±.5 mm, LP -4.4±.9 mm, P=.01) and for 3-D volume (OP -2±1%, LP -15±3%, P=.0001). Changes exceeding clinical thresholds for AAA size change (5 mm diameter or 5% volume) differed significantly within 12 months post-op for the 2 groups (Table). By volume, 33% of aneurysms in the OP group enlarged significantly within 1 year, most of them (63%) without detected endoleak. In the LP group, the 3 AAAs enlarging by volume at 1 year all had endoleak. Endoleak rates were similar (OP 18%, LP 29%; P = .2). There was no aneurysm rupture or aneurysm-related death.

CONCLUSIONS: In this multicenter study, changes in graft material permeability appear to have altered AAA behavior. Core lab data indicate AAAs with the LP device shrink significantly faster than AAAs with the original device. Within 1 year of implantation, AAAs in the LP group had twice the rate of clinically significant shrinkage. More importantly, AAAs in the LP group had a markedly lower incidence of expansion by volume. It is also notable that the majority of AAAs in the OP group expanded without detected endoleak, while there was no expansion without endoleak in the LP group.