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

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.

To study our hypothesis by comparing the follow-up angiographic outcomes of stented and nonstented incompletely coiled aneurysms.

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.

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).

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.