Objective It is well known that coiled aneurysms may recanalize over time, making follow-up evaluation mandatory. However, midterm and long-term outcome of re-embolization in recurred aneurysms after coil embolization has not been adequately investigated. We generated estimates of the re-treatment outcomes during follow-up monitoring, analyzing risk factors related to the further recanalization.

Methods A total of 133 aneurysms in 129 patients were retrospectively reviewed, each subjected to re-embolization for major recanalization after initial coil embolization, and to midterm and extended monitoring after the re-treatment. Cumulative medical records and radiologic data were assessed. Further recurrence rates and related risk factors were assessed using binary logistic regression analysis.

Results A total of 47 aneurysms (35.3%) displayed recanalization at 6 months postembolization, with 17 and 30 instances of minor and major recanalization, respectively. Multivariate analysis indicated that posterior circulation (HR=6.129; p=0.010), incomplete occlusion at time of second coiling (HR=9.975; p=0.001) and large-sized aneurysm (>7 mm) at time of fist coiling (HR=13.598; p<0.001). In 86 aneurysms showing complete occlusion at mid-term, 76 were further evaluated (≥12 months), displaying 18 aneurysms (23.7%) of delayed recanalization (minor, 14; major, 4) during a follow-up of 230.1 aneurysm-year (annual delayed recanalization rate: 7.8% aneurysm-year). Out of 15 aneurysms with minor recanalization at 6 month and with extended follow-up ((≥12 months), progression to major recanalization was observed in 6 aneurysms (40.0%) during a follow-up period of 44.0 aneurysm-year (annual progression rate: 13.6% aneurysm-year).

Conclusions Majority of re-coiled aneurysms (64.7%) displayed complete occlusion at 6 month follow-up. However, posterior circulation, incomplete occlusion at time of second coiling, and large aneurysm size before the treatment were predisposed to further recanalization. Mid-term recanalization rate in the re-embolized aneurysms seems to be higher than initial aneurysm.

Disclosures Y. Cho: None. H. Kang: None. M. Han: None.