Polymer based endografts have improved rates of proximal aortic neck dilatation and migration

Proximal aortic neck dilatation (PND) affects a considerable proportion of patients undergoing endovascular aneurysm repair (EVAR) and is associated with increased rates of type I endoleak (EL1), migration, and reinterventions. Although there are numerous studies investigating PND following the placement of endografts that utilize self-expanding stent (SES) technology, there are few reports for patients treated with endografts that utilize polymer-filled rings. The purpose of this study is to examine PND and graft migration after EVAR with the Ovation stent graft.

The study comprised patients who underwent EVAR as part of the prospective, international, multicenter Ovation stent graft trial. A clinical events committee adjudicated adverse events through 1 year, an independent imaging core laboratory analyzed imaging through 5 years, and a data safety and monitoring board provided study oversight. Neck diameter was measured at the level of the lowest renal artery. PND was defined as neck enlargement of 3 mm or more. Graft migration was defined as distal movement >10 mm or movement ≤10 mm when resulting in secondary intervention.

A total of 238 patients received this device during the study period. Patients were predominantly male (81%), with a mean age of 73 ± 8 years. Median follow-up was 58 months (IQR 36-60). Almost half the patients (110 patients, 46%) had challenging anatomy; defined as outside the instructions for use (IFU) with other commercially available stent grafts. 41 patients (17.2%) had a proximal neck length <10 mm and 93 (39%) had a minimum access vessel diameter <6 mm. The technical success rate was 100%. The 1-, 3- and 5-year overall survival rates were 96.6%, 86.2% and 74.9%, respectively. The immediate postoperative proximal neck diameter ranged from 16 mm to 31 mm with a mean of 22.4 ± 3 mm. During follow-up, ten patients (4.2%) developed PND. Freedom from PND estimates at 1, 3 and 5 years were 97.7%, 96%, and 93.6%, respectively. None of the patients developed endograft migration.

The use of the Ovation stent graft was associated with low rates of PND despite challenging neck anatomy in 17% of patients. No graft migration was observed. The design of this endograft may explain its superiority to SES in preventing neck dilatation and migration even in patients with challenging neck anatomy. This is important, as we continue to see significant late failures of EVAR due to proximal neck degeneration.