Aortic neck enlargement after endovascular aneurysm repair using balloon-expandable versus self-expanding endografts

Abstract

Objective: This study evaluated changes in aortic neck diameter after endovascular aneurysm repair (EVAR) using a balloon-expandable stent (BES) endograft compared with a commercially available self-expanding stent (SES) endograft. We hypothesized that forces applied to the aortic neck by SES endografts may induce aortic neck enlargement over time and that such enlargement may not occur in aneurysm patients treated with a device that does not use a proximal SES.

Methods: This was a retrospective quantitative computed tomography (CT) image analysis of patients treated with the Nellix (Endologix, Irvine, Calif) BES (n = 49) or the Endurant II (Medtronic, Minneapolis, Minn) SES (n = 56) endograft from 2008 to 2010. Patients with preimplant, postimplant, and at least 1-year serial CT scans underwent quantitative morphometric assessment by two independent vascular radiologists blinded to the outcome results. Changes in the infrarenal neck over time were compared with the suprarenal aorta for each patient.

Results: Follow-up extended to 4.8 years for the BES and to 4.6 years for the SES, with no significant difference in median follow-up time (34 months for BESs and 24 months for SESs; P = .06). There were no differences in preimplant neck diameter (25.2 ± 0.9 mm vs 25.7 ± 1.1 mm; P = .54) or length (27.7 ± 3.7 mm vs 23.6 ± 3.7 mm; P = .12) between BESs and SESs at baseline. After implantation, neck diameter increased by 1.1 ± 0.5 mm in BES patients and 2.6 ± 0.5 mm in SES patients (P = .07) compared with the preoperative diameter. At 3 years, neck diameter increased by 0.5 ± 0.9 mm in BES patients and by 3.8 ± 1.0 mm in SES patients (P = .0002) compared with the first postoperative CT scan. The annual postimplant rate of increase in the infrarenal neck diameter was fivefold greater in SES patients (1.1 ± 0.1 mm/y) than in BES patients (0.22 ± 0.04 mm/y; P < .0001). There were no significant differences in the diameter of the suprarenal aorta at baseline or at 3 years and no differences in the annual rate of change in suprarenal aortic diameter between BES and SES endografts.

Conclusions: EVAR using SES endografts resulted in progressive infrarenal aortic neck enlargement, whereas EVAR using BES endografts resulted in no neck enlargement over time. These data suggest that infrarenal neck enlargement after EVAR with SES endografts is likely related to the force exerted by SES elements rather than disease progression in the infrarenal neck.