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

Abstract

BackgroundNeo-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 MethodsAll 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).ResultsFrom 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).ConclusionNIH 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.

Delayed Stroke after Aneurysm Treatment with Flow Diverters in Small Cerebral Vessels: A Potentially Critical Complication Caused by Subacute Vasospasm

“…Recently, a comparable but less striking association between stent oversizing, employing conventional aneurysm stents with significantly lower endovascular surface coverage, and luminal reduction of the proximally and distally adjacent cerebral vessel lumen was reported, but was rated to be clinically non-significant [25].…”

Preliminary in vitro angiographic comparison of the flow diversion behavior of Evolve and Pipeline devices

“…Device coverage at the neck needs to be compared with high resolution imaging such as optical coherence tomography 31 32. Differences in stent design have been shown to result in different degrees of neointimal hyperplasia 33. Only three deployments were evaluated here, and the silicone models do not have perforators/branches.…”

p64 flow diverter: Results in 108 patients from a single center

“…Before treatment patients should be recommended best medical management of their cardiovascular risk factors to prevent an excessive neo-intimal reaction. 23 In a study by Aguilar Pérez 26 concerning this issue for the p64 in over 200 patients, almost a third had some degree of in-stent stenosis during any time at follow-up. Most stenoses were mild, and no progression to occlusion occurred.…”

“…In-stent stenosis by intimal hyperplasia and distal tapering is a clinical concern with flow diversion. 23–25 In one study, neo-intimal hyperplasia was positively correlated with smoking, dyslipidemia, and high blood pressure, but not with aneurysm characteristics. Although early follow-up hyperplasia was more frequently associated with the use of the SILK stent rather than the Pipeline Embolization Device, at long-term follow-up, the neo-intimal hyperplasia rate in the total population dropped from 55% to 26% with no more significant difference between the two stents.…”