Introduction Although aneurysms incompletely occluded after coil embolization are subject to recanalization, complete occlusion may evolve in some aneurysms during follow-up in clinical practice, even though the sac fills with contrast immediately after coiling. Stent usage may augment the progressive thrombosis within coiled aneurysms. We evaluated outcomes of small aneurysms (<10 mm) that showed filling of the sac with contrast immediately after stent-assisted coiling and assessed factors implicated in subsequent the progressive occlusion.

Methods Between September 2012 and June 2016, a total of 463 intracranial aneurysms were treated by stent-assisted coil embolization. Of these, 132 small saccular aneurysms displayed filling of the sac by contrast immediately after the coiling. TOF-MRA or conventional angiography were used for postoperative monitoring according to our institutional protocol. Progressive thrombosis was defined as complete occlusion of these aneurysms at the 6-month follow-up. Progressive occlusion rates and related risk factors were assessed using binary logistic regression analysis.

Results In 101 (76.5%) of the 132 aneurysms that showed filling of the sac with contrast, complete occlusion was observed on follow-up imaging studies at 6 months. Binary logistic regression analysis demonstrated that progressive occlusion was linked to smaller neck diameter (p=0.003; OR=1.533), hyperlipidemia (p=0.036; OR=3.329) and stent type (p=0.031). LVIS stent is susceptible to progressive thrombosis than Neuroform stent (p=0.008; HR=10.204) or Enterprise stent (p=0.098; HR=3.154). In 57 progressively thrombosed aneurysms with follow-up evaluations ≥12 months (mean, 25.0±10.7 months, median 18 months), 56 aneurysms (98.2%) exhibited stable occlusion, whereas minor recanalization was observed in only one (1.8%) instances, and major recanalization occurred in none.

Conclusion In small saccular aneurysms occluded incompletely after stent-assisted coil embolization, aneurysms with smaller neck diameters or hyperlipidemia, and LVIS deployment seem predisposed to progressive intra-aneurysmal thrombosis over the course of time.

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