Stent-associated flow remodeling causes further occlusion of incompletely coiled aneurysms

Background: Incomplete coil occlusion is associated with increased risk of aneurysm recurrence. We hypothesize that intracranial stents can cause flow remodeling, which promotes further occlusion of an incompletely coiled aneurysm. Objective: To study our hypothesis by comparing the follow-up angiographic outcomes of stented and nonstented incompletely coiled aneurysms. Methods: From January 2006 through December 2009, the senior author performed 324 initial coilings of previously untreated aneurysms, 145 of which were Raymond classification 2 and 3. Follow-up angiographic studies were available for 109 of these aneurysms (75%). Angiographic outcomes for stented vs nonstented incompletely coiled aneurysms were compared. A multivariate analysis was performed to identify factors related to the progression of occlusion at follow-up, with adjustment for aneurysm location, size, neck size, Hunt-Hess grade, stent use, initial Raymond score, packing density, age, sex, and medical comorbidities. Results: Of the 109 aneurysms, 37 were stented and 72 were not stented. With a median follow-up time of 15.4 months, 33 stented aneurysms (89%) progressed to complete occlusion compared with 29 nonstented aneurysms (40%). Recanalization rates were lower in the stented group (8.1%) compared with the nonstented group (37.5%; P < .001). On multivariate analysis, stent use (odds ratio, 18.5; 95% confidence interval, 4.3-76.9) and packing density (odds ratio, 1.093; 95% confidence interval, 1.021-1.170) were significant predictors of the progression of occlusion. Aneurysm size was negatively correlated with the progression of occlusion (odds ratio, 0.844; 95% confidence interval, 0.724-0.983). Conclusion: Stent-assisted coiling causes progression of occlusion, possibly by a flow remodeling effect. The odds of progression of occlusion of stent-coiled aneurysms were 18.5 times that of nonstented aneurysms.