Thromboembolic Events Detected by Diffusion-Weighted Magnetic Resonance Imaging after Flow Diverter Treatment: The Impact of Procedure Time

Flow diverter surface modifications for aneurysm treatment: A review of the mechanisms and data behind existing technologies

Flow diversion (FD) has become a mainstay treatment for large wide-necked aneurysms. Despite excellent safety and efficacy, the risk of thromboembolic complications necessitates the use of dual antiplatelet therapy (DAPT). The use of DAPT makes hemorrhagic complications of stenting carry high morbidity and mortality. Additionally, DAPT usage carries a risk of "nuisance" complications that do not directly impact intracranial circulation but need to be managed nonetheless. To circumvent this issue, the most recent generation of flow diverters have undergone surface modification with various compounds to confer blood compatibility to limit clotting and thrombosis. While these newer generation flow diverters are marketed to enhance ease of deployment, the goal is to eventually facilitate single antiplatelet use with flow diverter treatment. This generation of FDs have potential to expand indications beyond unruptured wide-necked aneurysms to include ruptured intracranial aneurysms without the necessity of DAPT. Currently, no comprehensive review details the molecular mechanisms and pre-clinical and clinical data on these modifications. We seek to fill this gap in the literature by consolidating information on the coating technology for four major FDs currently in clinical use-PipelineTM Flex and Vantage Shield TechnologyTM, FREDTMX, p48/64 hydrophilic coating, and Acandis Dervio® 2heal-to serve as a reference guide in neurointerventional aneurysm treatment. Although the Balt silkTM was one of the first FDs, it is uncoated, thus we will not cover this device in our review. A literature review was performed to obtain information on each coating technology for the major flow diverters currently on the market using international databases (PUBMED, Embase, Medline, Google Scholar). The search criteria used the keywords for each coating technology of interest "phosphorylcholine," "poly 2-methoxyethyl acrylate," "hydrophilic polymer coating," and "fibrin-heparin" Keywords related to the device names "Pipeline Shield," "Pipeline Shield with Flex Technology," "FRED," "FREDX," "p64," "p64-HPC," "Derivo 2heal" were also used. Studies that detailed the mechanism of action of the coating, any pre-clinical studies with surface-modified intravascular devices, and any clinical retrospective series, prospective series, or randomized clinical trials with surface-modified devices for aneurysm treatment were included.

Diffusion-weighted imaging lesions after endovascular treatment of cerebral aneurysms: A network meta-analysis

Background

Thromboembolism is one of the common complications in endovascular treatments including coiling alone, stent-assisted coiling (SAC), balloon-assisted coiling (BAC), and flow-diverting (FD) stents. Such treatments are widely used in intracranial aneurysms (IAs), which usually present as positive lesions in diffusion-weighted imaging (DWI). Whether these adjunctive techniques increase postprocedural DWI-positive lesions after endovascular treatment remains unclear.

Methods

A thorough electronic search for the literature published in English between January 2000 and October 2022 was conducted on PubMed, Medline, and EMBASE. Eighteen studies (3 cohort studies and 15 case-control studies) involving 1,843 patients with unruptured IAs (UIAs) were included. We performed a frequentist framework network meta-analysis (NMA) to compare the rank risks of cerebral thromboembolism of the above four endovascular treatments. The incoherence test was used to analyze the statistical disagreement between direct and indirect evidence. Funnel plots were used to analyze publication bias.

Results

The incidences of DWI lesions in patients who received FD stents, SAC, BAC, and coiling alone were 66.1% (109/165), 37.6% (299/795), 31.1% (236/759), and 25.6% (236/921). The incidence of DWI lesions in patients who received FD stents was higher than that in patients who received SAC [OR: 2.40; 95% CI (1.15, 5.00), P < 0.05], BAC [OR: 2.62; 95% CI (1.19, 5.77), P < 0.05], or coiling alone [OR: 2.77; 95% CI (1.26, 6.07), P < 0.05]. The incoherence test showed preferable consistency in this NMA. No obvious publication bias was found in the funnel plot.

Conclusion

FD stent placement brings more ischemic lesions identified by DWI than any other procedures for patients with UIA. The characteristics of FD stents may result in a high incidence of DWI lesions.