Impact of Coil Packing Density and Coiling Technique on Occlusion Rates for Aneurysms Treated with Stent-Assisted Coil Embolization.

Background And Objective: Stent-assisted coil embolization is an established endovascular technique for wide-necked intracranial aneurysms. Although recanalization after coil embolization is reduced with the use of a stent, the impact of aneurysm packing density is less clear in stent-coiled aneurysms. The purpose of the present study was to assess packing density in stent-coiled aneurysms and evaluate its effect on recanalization and retreatment.

Methods: A retrospective analysis of consecutive aneurysms treated with stent-assisted coiling was performed at 2 academic institutions between 2007 and 2015. Aneurysm occlusion was assessed using digital subtraction angiography. Packing density was calculated using the AngioCalc app.

Results: Two hundred fifty-three aneurysms were identified (median age, 59 years). The median packing density was 35.3%. At last follow-up, 72.7% of aneurysms were completely obliterated and 19.4% had a neck remnant. Complete occlusion was associated with smaller aneurysms and coiling through stent interstices. A higher packing density was associated with increased rate of complete occlusion when analyzed as continuous variable. After adjustment for confounding variables, packing density was no longer predictive of complete occlusion (odds ratio = 1.018, P = 0.122). Similarly, there was no significant association between aneurysm occlusion, retreatment, and packing density when assessed by categories of high (>22%), moderate (12%-22%), and low (<12%) packing density.

Conclusions: Aneurysm size remains the most important predictor of aneurysm recanalization and retreatment after stent-assisted coiling. Although higher packing densities were associated with increased rates of aneurysm occlusion in unadjusted statistical comparisons, this finding was no longer significant after adjusting for confounders.