In-stent stenosis after stent-assisted coiling: Incidence, predictors and clinical outcomes of 435 cases

Background: Neuroform and Enterprise are widely used self-expanding stents designed to treat wide-necked intracranial aneurysms. Objective: To assess the incidence, clinical significance, predictors, and outcomes of in-stent stenosis (ISS). Methods: Angiographic studies and hospital records were retrospectively reviewed for 435 patients treated between 2005 and 2011 in our institution. A multivariable regression analysis was conducted to determine the predictors of ISS. Results: The Neuroform stent was used in 264 patients (60.7%) and the Enterprise in 171 patients (39.3%). A total of 11 patients (2.5%) demonstrated some degree of ISS during the follow-up period at a mean time point of 4.2 months (range, 2-12 months). The stenosis was mild (< 50%) in 8 patients (1.8%), moderate (50-75%) in 2 patients (0.5%), and severe (> 75%) in 1 patient (0.2%). No patients were symptomatic or required further intervention. There was complete ISS resolution in 2 patients, partial resolution in 2 patients, and no change in 5 patients on follow-up angiography. Patients developing ISS were significantly younger than those without ISS (40.3 vs 54.9 years; P < .001). ISS rates were 2.7% with the Neuroform and 2.3% with the Enterprise stent (P = .6). In multivariable analysis, younger patient age (odds ratio = 0.92; P = .008), carotid ophthalmic aneurysm location (odds ratio = 7.7; P =0.01), and carotid terminus aneurysm location (odds ratio = 8.1; P = .009) were strong independent predictors of ISS. The type of stent was not a predictive factor. Conclusion: Neuroform and Enterprise ISS is an uncommon, often transient, and clinically benign complication. Younger patients and those harboring anterior circulation aneurysms located at ophthalmic and carotid terminus locations are more likely to develop ISS. Abbreviations: ISS, in-stent stenosisSAC, stent-assisted coiling.