Stent Migration Following Endovascular Sealing of Abdominal Aortic Aneurysms

Introduction - We investigated the incidence and extent of stent migration after endovascular sealing of abdominal aortic aneurysms (EVAS), its relationship with adherence to the instructions for use of the Nellix endograft and its association with aneurysm growth. Methods - In this retrospective single centre study, we reviewed clinical data and follow-up CT images of patients undergoing infra-renal EVAS with a minimum follow-up of 1 year. The first postoperative CT scan at one month and the subsequent scans were used to measure the distances between the proximal end of the stent and reference visceral vessels using a previously validated technique. Device migration was based on both the Society of Vascular Surgery definition of ≥10mm and a specific EVAS migration definition of ≥4mm. Patients were categorised according to adherence to the old (2013) or new (2016) Nellix IFU. Aneurysm diameter was measured for each scan and a change of ≥5mm was deemed indicative of aneurysm growth. Results - Seventy-six patients were eligible for inclusion in our study. Over a 4-year period, migration ≥4mm occurred in 42 (55%) patients and migration of ≥10mm in 16 (21%), with similar incidence in right and left stents. Migration was significantly more frequent among patients whose anatomy did not conform to any IFU (p=0.025). Presence of aneurysm growth ≥5mm was significantly associated with migration ≥4mm (p=0.03). Conclusion - Infra-renal EVAS is prone to migration, particularly when performed outside IFU. The definition of migration used for EVAR is inappropriate for EVAS; a new consensus on definition and measurement technique is necessary.