Comparison between Onyx and coil embolization for persistent type 2 endoleaks after endovascular aneurysm repair

Type 2 endoleaks (T2EL) are the most common form of endoleaks after endovascular aneurysm repair (EVAR). Several studies on the feasibility of embolization using ethylene vinyl alcohol copolymer (Onyx, Medtronic) for T2EL have been reported. The purpose of this study was to compare coil and Onyx embolization for T2EL treatment after EVAR. Between August 2005 and July 2022, 46 patients underwent endovascular embolization for treatment of T2EL (15 Onyx and 31 coils). The primary endpoint was endoleaks resolution or significant aneurysm sac growth of >5 mm in maximal diameter after T2EL embolization. In addition, periprocedural factors, reintervention, sac rupture, and survival analysis were assessed. The follow-up period after embolization was significantly shorter in the Onyx group (11.6 months 34.7 months, P = 0.016), and there was no difference in aneurysm sac growth rate between both groups (20.0% 51.6%; P = 0.472, log-rank test). However, cases with multiple endoleak origins tended to be treated with Onyx (P = 0.002). When applying Onyx, there was no significant difference in results between the transarterial and translumbar approaches. There appears to be no significant difference in the results of Onyx and coil embolization for T2EL treatment, although it is difficult to evaluate effectiveness due to the small number of cases and short follow-up period. However, in cases of multiple origin endoleaks or when the transarterial approach is not feasible, the Onyx by translumbar approach may be a more effective method.