The occurrence of neointimal hyperplasia after flow-diverter implantation is associated with cardiovascular risks factors and the stent design.

BACKGROUND: Neo-intimal hyperplasia (NIH) is frequently observed after flow-diverter stent (FDS) implantation. Although mostly asymptomatic, this vascular response can sometimes lead to delayed ischemic strokes. This study intended to evaluate the factors potentially influencing the rates of NIH following FDS treatment. MATERIAL AND METHODS: All aneurysm treatments performed with a Pipeline embolization device (PED) or a SILK stent from May 2011 to May 2015 were collected in a prospectively maintained database. Patient demographics, clinical, and angiographic outcomes including both digital subtraction angiography and C-arm cone-beam CT were registered. Two blind reviewers rated the presence of NIH on a binary scale (present/absent). RESULTS: From 148 patients, 63 datasets were available for analysis. Inter-reader agreement was excellent (Kappa=0.88). NIH was positively correlated with smoking, dyslipidemia, and high blood pressure, but not with aneurysm characteristics. At early follow-up (<12 months), NIH was more frequently associated with the use of the SILK stent (68%) rather than the PED (38%): P<0.02. At long-term follow-up, the NIH rate in the total population dropped from 55% to 26% with no more significant difference between the two stents. The complete occlusion rate as seen in early follow-up was higher in the SILK group with 76% vs 65% but without statistical significance (P=0.4). CONCLUSION: NIH is a dual-vessel reaction after FDS implant. When planning a treatment in locations at risk of ischemic complications if severe NIH would occur, then the stent design should be considered. However, minimal NIH might also be needed as it is involved in aneurysm healing. Before treatment patients should be recommended best medical management of their cardiovascular risks factors to prevent an excessive NIH reaction.

Flow changes in the posterior communicating artery related to flow-diverter stents in carotid siphon aneurysms.

BACKGROUND: Flow-diverter stent (FDS) placement for treatment of intracranial aneurysms can cause flow changes in the covered branches. OBJECTIVE: To assess the impact of the treatment of carotid siphon aneurysms with FDS on the posterior communicating artery (PComA) flow. MATERIALS AND METHODS: Between February 2011 and January 2015, 125 carotid siphon aneurysms were treated with FDS. We retrospectively analyzed all cases with PComA ostial coverage. The circle of Willis anatomy was also studied as the flow changes in PComA postoperatively and during angiographic follow-up. Data from neurological examination were also collected. RESULTS: Eighteen aneurysms of the carotid siphon in 17 patients were treated with FDS covering the ostium of the PComA. Based on the initial angiography, patients were divided into two groups: the first with a P1/PComA size ratio >1 (10 cases) and the second with a ratio ≤1 (8 cases). Follow-up angiography (mean time of 10 months) showed 90% of PComA flow changes in group 1 but only 12.5% in group 2. There was a significant difference between the two groups (p=0.002). Nevertheless, no patient had new symptoms related to these flow changes during the follow-up period. CONCLUSIONS: In our experience, covering the PComA by FDS when treating carotid siphon aneurysms appeared safe and the P1/PComA ratio is a good predictor of flow changes in PComA.