Background Bifurcation aneurysms at the basilar and carotid tip with a dome-to-neck ratio of <1.6 (dome width/neck width) and aspect ratio <2 (dome height/neck width) are challenging both to treat and also to achieve a permanent occlusion. As a consequence of the water-hammer effect, there is a tendency to coil compaction or displacement of intrasaccular devices to a degree that demands retreatment in order to avoid aneurysm rupture. Different methods and devices have been developed to overcome these challenges, and the last developed and CE approved device is the eCLIPs. eCLIPs are deployed across and outside the aneurysm neck. It diverts the blood away from the aneurysm and gives support for coils. It does not impede access to side branches nor impair flow to perforators. Here we present our experience with eCLIPs in treating basilar tip aneurysms, both as a first treatment and as adjunct to retreatment of aneurysms formerly treated with both coils and WEB. Until now around 90 eCLIPs in total have been implanted, primarily in basilar tip aneurysms and a few in carotid tip aneurysms.Of them 23 are included in this study, as they fulfill both criteria with a dome-to-neck ratio of <1.6 and an aspect ratio of <1.2. 4 patients were not available for follow up (2 had not reached the time for the first follow-up, one refused follow-up, and one died post procedure), so the efficacy cohort comprises of 19 patients.

Results Procedural success was achieved in 22/23 patients (96%). There was one procedural safety event 1/23 (4.3%). No late morbidity and no recurrences were seen in the follow-up period. According to the modified Raymond-Roy score (mR-R), at the end of the index procedure 14 patients were mR-R 1 and 2, whereas 9 were 3A and 3B. At follow-up at 11.5 months (median), 16 patients were mR-R 1, 2 were mR-R 2 and one was mR-R 3.

Conclusion Good overall procedural and follow-up results. The results are indistinguishable from that of all eCLIPs cases, including those with more favorable dome-to-neck and and aspect ratios.

Disclosures L. Soerensen: 2; C; Evasc Neurovascular Enterprises, Vancouver. J. de Vries: 2; C; Evasc Neurovascular Enterprises, Vancouver. M. Holtmannspoetter: None. B. Turowski: None. T. Marotta: 5; C; Principal, Evasc Neurovascular Enterprises, Vancouver.