Long-term failure after endovascular aneurysm sealing in a real-life, single-center experience with the Nellix endograft

Abstract

Background: Endovascular aneurysm sealing (EVAS) is an innovative alternative to conventional endovascular aneurysm repair (EVAR). EVAS relies on sac anchoring without proximal fixation to achieve sealing and should have allowed for the treatment of a broader range of anatomic features compared with standard EVAR. Despite the encouraging early reports, the mid- and long-term follow-up data have shown increased rates of failure. To address the issue, the manufacturer introduced revised instructions for use (IFU) in 2016. The present study reports the outcomes of this system after a median follow-up of 45 months.

Methods: Data for all patients electively treated with EVAS at our institution were retrospectively collected. The patients were retrospectively reclassified according to the 2016 revised IFU of the device. All patients in the present series had undergone EVAS for the treatment of infrarenal abdominal aortic aneurysms (AAAs). The primary end point was therapeutic failure: graft migration >5 mm, sac expansion >5 mm, type IA endoleak (Is2 and Is3 using the Van den Ham classification), type Ib endoleak, and secondary rupture. The overall mortality, aortic-related mortality, and reintervention rates were also analyzed.

Results: A total of 101 patients had undergone elective treatment by EVAS from 2013 to 2018 for infrarenal AAAs. The median follow-up was 3.75 years. Therapeutic failure was observed in 31 of the 101 patients (30.7%), with no significant difference between the in-IFU and off-IFU 2016 subgroups. Failure occurred at a median interval of 34 months from the index procedure. Of the 101 patients, 6.9% had presented with secondary rupture. Freedom from aneurysm-related mortality was 96.9% at 1 and 2 years and 89.9% at 5 years. Freedom from reintervention decreased over time: 94.7% at 1 year, 77% at 4 years, and 52.1% at 6 years. Of the 101 patients, 14 (13.9%) had undergone emergent or elective graft explantation.

Conclusions: EVAS performed worse than conventional endografts for several critical end points, regardless of any preoperative anatomic parameters. The incidence of therapeutic failures tended to increase over time, especially 4 years after the index procedure.

Keywords: Abdominal aortic aneurysm; EVAR; EVAS; Nellix; Therapeutic failure.