Polymer-Based Endografts Have Improved Rates of Proximal Aortic Neck Dilatation and Migration

Abstract

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, migration and reinterventions. Although there are numerous studies investigating PND following the placement of endografts that use self-expanding stents, there are no such reports for patients treated with endografts that use polymer-filled sealing rings. The purpose of this study is to examine PND and graft migration after EVAR with the Ovation stent graft. The study included 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. Graft migration was defined as distal movement >10 mm or movement of ≤10 mm when resulting in secondary intervention. A total of 238 patients received this device during the study period. Patients were predominantly male (81%), elderly with a mean age of 73 ± 8 years. Median follow-up was 58 months (interquartile range, 36-60). Almost one-half the patients (110 patients, 46%) had a challenging anatomy defined as outside the instructions for use with other 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 75%, respectively. The immediate postoperative proximal neck diameter ranged from 15.5 to 31.4mm with a mean of 22 ± 3 mm. During follow-up, four patients (1.7%) developed PND. Freedom from PND estimates at 1, 3 and 5 years were 99%, 97.9% and 97.9%, respectively (Figure). None of the patients developed significant endograft migration. The use of the Ovation stent graft was associated with excellent Results with very low rates of PND despite challenging neck anatomy in 39% of patients. No graft migration was observed. The design of this endograft may explain its superiority to self-expanding stents in preventing neck dilatation and migration. This is important, as we continue to see significant late failures of EVAR due to proximal neck degeneration.