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Abstract
Background Flow diversion is an innovative and increasingly used technique for the treatment of intracranial aneurysms. New flow diverters (FDs) are being introduced to improve the safety and efficacy of this treatment. The aim of this study was to assess the safety, feasibility, and efficacy of the new Pipeline Vantage (PV) FD.
Methods Patients with intracranial aneurysms treated with the PV at 10 international neurovascular centers were retrospectively analyzed. Patient and aneurysm characteristics, procedural parameters, complications, and the grade of occlusion were assessed.
Results 60 patients with 70 aneurysms (5.0% with acute hemorrhage, 90.0% located in the anterior circulation) were included. 82 PVs were implanted in 61 treatment sessions. The PV could be successfully implanted in all treatments. Additional coiling was performed in 18.6%, and in-stent balloon angioplasty (to enhance the vessel wall apposition) in 24.6%. Periprocedural technical complications occurred in 24.6% of the treatments, were predominantly FD deployment problems, and were all asymptomatic. The overall symptomatic complication rate was 8.2% and the neurological symptomatic complication rate was 3.3%. Only one symptomatic complication was device-related (perforator artery infarctions leading to stroke). After a mean follow-up of 7.1 months, the rate of complete aneurysm occlusion was 77.9%. One patient (1.7%) died due to aneurysmal subarachnoid hemorrhage which occurred before treatment, unrelated to the procedure.
Conclusions The new PV FD is safe and feasible for the treatment of intracranial aneurysms. The short-term occlusion rates are promising but need further assessment in prospective long-term follow-up studies.
- aneurysm
- flow diverter
- angiography
- intervention
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
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INTRODUCTION
Endoluminal vessel reconstruction using flow diverters (FDs) is an innovative and increasingly used technique for the treatment of intracranial aneurysms.1–4 Multiple studies have investigated the safety and efficacy of FD treatments and demonstrated that even complex aneurysms, which could only be treated with significant difficulty using more established techniques in the past, if at all, can be effectively treated by flow diversion.1–8 Despite the predominantly positive results of these studies, there are still several challenges, which are not seldomly encountered during or after FD treatment, such as technical difficulties during the implantation of the device, suboptimal opening of the stent, and thrombotic complications. New FDs are being introduced to overcome these issues, to increase the rate of complete occlusion, and thus to improve the safety and efficacy of this treatment.9–11
The Pipeline Embolization Device (PED; Medtronic Neurovascular, Irvine, CA), including its successors, is one of the most frequently implanted FDs worldwide.5–8 12 13 The new version of the PED, which was introduced only recently as limited market release, is the Pipeline Vantage Embolization Device with Shield Technology (hereafter referred to as Pipeline Vantage (PV)), which features several modifications in comparison to its precursor, the Pipeline Flex with Shield Technology, such as a new wire design, a lower thickness of the device, and a higher pore density.
The aim of this multicenter study was to assess the periprocedural safety and feasibility, as well as the short-term efficacy, of the new PV FD for the treatment of intracranial aneurysms.
Methods
Study design
This is a retrospective, multicenter, observational study at 10 international high-volume neurovascular centers. Based on a survey specifically designed for this study, which was completed by the interventionalists who used the device, the clinical and radiological records of patients with intracranial aneurysms, who were treated with the PV between January 2020 and June 2020, were systematically reviewed. Institutional ethic committees approved this study.
Patient characteristics
Patient data included age, sex and initial clinical presentation, as well as the pre- and post-treatment modified Rankin Scale (mRS). For patients who presented with an acutely ruptured intracranial aneurysm, the severity of subarachnoid hemorrhage was assessed according to the Hunt and Hess scale.
Aneurysm characteristics
The recorded characteristics of the treated intracranial aneurysms included the aneurysm location, type (saccular or fusiform), size (maximal diameter) and neck diameter of the aneurysm, as well as the diameter of the parent vessel proximal and distal to it. Wide-necked aneurysms were defined as follows: neck diameter ≥4 mm or dome-to-neck ratio <2.
Device characteristics
The participating centers received the devices as part of a limited market release.
Images of the PV and of its precursor, the Pipeline Flex, are shown in figure 1. The PV consists of either 48 or 64 drawn filled tube (DFT) wires, consisting of an inner platinum wire and an outer cobalt-chromium wire with the 64-wire device having additionally 16 pure cobalt-chromium wires, while its precursor, the Pipeline Flex, consists of 75% cobalt chromium and 25% platinum tungsten wires. In comparison to the Pipeline Flex with Shield Technology, the wires of the PV are smaller in diameter, providing a lower overall thickness of the device. Another difference is the density of the pores between the DFT wires, which is higher for the 64-wire PV devices, while the metal coverage is similar. For example, in a 4.00–4.25 mm vessel, the pore density of the 4.5 mm PV is 18–19 pores/mm2 and the metal coverage 23–24%, while for the 4.25 Pipeline Flex with Shield Technology, the pore density is only 12–14 pores/mm² and the metal coverage 23–26% (parameters provided by the manufacturer). The deployment technique of the PV is similar to the Pipeline Flex. The recommended delivery systems are the Phenom 21 and the Phenom 27 microcatheter (Medtronic Neurovascular) for devices ≤3.5 mm and ≥3.5 mm, respectively (at 3.5 mm size there are two versions which are used through either a Phenom 21 or a Phenom 27 microcatheter).
Images and schematic illustration of the Pipeline Flex and the Pipeline Vantage. Macroscopically, the Pipeline Flex (A) and the Pipeline Vantage (B) look very similar. The Pipeline Flex is made of 75% cobalt chromium wires (black lines/tube in A) and 25% platinum tungsten wires (gray lines/tube in A), while the wire design of the Pipeline Vantage is based on drawn-filled tube wires, consisting of an inner platinum wire (black tube in B) and an outer cobalt-chromium wire (gray tube in B). Further differences are the diameters of the wires, which are smaller for the Pipeline Vantage, resulting in a lower overall thickness of the device, and the density of the pores between the wires, which is higher for the 64-wire Pipeline Vantage devices, while the metal coverage is similar compared to the Pipeline Flex.
Procedural characteristics, feasibility and safety
The recorded procedural parameters included the peri-interventional medical treatment, the reason for choosing the PV, and the treatment technique, such as additional coiling, the number of implanted devices, and the need for in-stent balloon angioplasty.
Using a 5-point scale (1: very poor, 2: poor, 3: intermediate, 4: good, 5: very good), the ease of deployment, the vessel wall apposition, and the radiopacity of the device were rated overall by the treating interventionalist for each treatment. The general performance of the PV was compared with its precursor, the Pipeline Flex with Shield Technology, using another 5-point scale (1: worse, 2: slightly worse, 3: equivalent, 4: slightly better, 5: better) for each treatment.
Periprocedural technical complications were assessed by the treating interventionalist. Peri- and postprocedural symptomatic complications until discharge and during the follow-up period were assessed. Clinical evaluation was performed by board-certified neuroradiologists, neurosurgeons or neurologists before the procedure, immediately after the procedure, 24±6 hours after the procedure, at discharge, and at the follow-up visits. The patients’ clinical condition was assessed using the mRS.
The degree of in-stent stenosis was assessed and categorized as ‘not present’, ‘mild’ (defined as ≤50% stenosis, compared with the immediate post-interventional diameter), ‘moderate’ (50–75%), ‘severe’ (>75%) or ‘complete occlusion’.
The grade of occlusion of the aneurysm immediately after the procedure was reported according to the O’Kelly-Marotta (OKM) scale.14 Since invasive angiography was not available for all follow-ups, the grade of occlusion at the latest follow-up was reported according to the Raymond-Roy classification (RROC) for aneurysms treated using an FD only and to the modified RROC (mRROC) for aneurysms treated with FD plus coiling.15 Adequate occlusion was defined as complete occlusion or residual neck (OKM C and D/mRROC I and II). For aneurysms with side-branches integrated into the aneurysm sac, the Cekirge-Saatci-Classification (CSC) was reported additionally.16
Results
Patient and aneurysm characteristics
Sixty patients with 70 aneurysms were included in this study. The patient and aneurysm characteristics are summarized in table 1.
Patient and aneurysm characteristics
The mean±SD age of the patients was 53.9±13.7 years. Forty-one patients were female. The pre-treatment mRS was 0.5±1.1 (mRS 0 in 44 patients (73.3%), mRS 1 in 13 patients (21.7%), mRS 4 in one patient (1.7%), and mRS 5 in two patients (3.3%)). The three patients with mRS ≥4 presented with an acute aneurysmal subarachnoid hemorrhage with a Hunt and Hess scale of 1, 3 and 5, respectively. The most frequent clinical presentation was headache (40.0%), followed by regrowth or persistence of a previously treated aneurysm (16.7%), subarachnoid hemorrhage (5.0%), and ischemic stroke, ptosis or seizures (1.7%, respectively). In 20 patients (33.3%) the aneurysm was incidental and asymptomatic.
The number of aneurysms treated in the respective treatment session was one in 53 treatments (86.9%), two in seven treatments (11.5%), and three in one treatment (1.6%). The most frequent aneurysm locations were the internal carotid artery (ICA; 50.0%), the middle cerebral artery (MCA; 24.3%), and the anterior communicating artery (ACOM; 8.6%). The maximal diameter of the aneurysms was 8.2±6.6 mm (range 2–32 mm). Most aneurysms had a wide neck (72.9%), a saccular configuration (88.6%), and were sidewall aneurysms (65.7%). The parent vessel diameter was 3.6±1.0 mm proximal and 3.0±0.9 mm distal to the aneurysm. Of the treated aneurysms, 34 (48.6%) had side branches integrated into the aneurysm sac.
Antiplatelet therapy
The pre-, peri- and post-procedural antiplatelet therapy, as well as the testing of thrombocyte aggregation response, were performed according to the respective institutional standards. The most common peri-interventional antiplatelet therapy was acetylsalicylic acid (ASA) in combination with clopidogrel (44.3%), followed by prasugrel only (34.4%), and ASA in combination with prasugrel (14.8%). ASA in combination with ticagrelor was administered in 4.9% and ticagrelor in 1.6%. Platelet reactivity testing was performed in 88.5%.
Treatment
The treatment characteristics are summarized in table 2. Two example cases are illustrated in figures 2 and 3.
Flow diverter implantation and coiling of a symptomatic, unruptured aneurysm of the internal carotid artery. Digital subtraction angiography (A, B) and three-dimensional reconstructions of a rotational angiography (C showing the aneurysm from the contralateral, D from the ipsilateral site) show a large aneurysm of the right internal carotid artery (ICA) with a maximal diameter of 24 mm. After positioning of a Phenom 27 microcatheter in the ICA distal to the aneurysm, another microcatheter for coiling was navigated into the aneurysm. After subtotal deployment of a 5×40 mm Pipeline Vantage flow diverter (E), subtotal coiling of the aneurysm was performed. The angiographies immediately after coiling show persistent filling of the aneurysm (F, G). In the control angiography 1 year after the treatment, the aneurysm was completely occluded (H, I). Minimal thickening of the vessel wall with no associated stenosis was noted at the proximal portion of the stent (black arrows in I).
Flow diverter implantation for the treatment of an aneurysm of the middle cerebral artery (MCA) bifurcation. Digital subtraction angiography (A) and three-dimensional reconstructions of a rotational angiography (B) show an aneurysm located at the bifurcation of the right MCA with integration of the superior trunk into the aneurysm sac. Using a Phenom 21 microcatheter, a Pipeline Vantage flow diverter was implanted, extending from the proximal inferior trunk to the M1 segment of the MCA, covering the aneurysm and the integrated superior trunk (C). Angiography immediately after the implantation (D) showed moderate stasis of contrast agent within the aneurysm sac. In the follow-up angiography 6 months after treatment (three-dimensional reconstructions of rotational angiography shown in E, digital subtraction angiography shown in F), the aneurysm was completely occluded with patency of the integrated M2 branch.
Treatment characteristics, complications and occlusion rates
One or more PVs were successfully implanted in all 61 treatments, with a total number of 82 implanted PVs. The most frequently reported reasons for choosing the PV were a wide neck of the aneurysm (72.9%), a fusiform shape (8.6%), a failed previous treatment (7.1%). and multisegmental disease (7.1%). The number of implanted FDs per treatment was one in 44 treatments (72.1%), two in 15 treatments (24.6%), and ≥3 in two treatments (3.2%). In one treatment (1.6%), in a patient with a multisegmental disease, two FDs were implanted covering three aneurysms. In another treatment (1.6%), also in a patient with a multisegmental disease, a large fusiform aneurysm was treated using five FDs. In seven treatments (11.5%), two FDs were implanted for the treatment of one aneurysm. In the remaining 51 patients (83.6%), one FD was implanted for the treatment of one aneurysm, respectively. In 56 of 61 treatments (91.2%), the first PV selected was appropriate and was actually implanted, while in five cases (8.2%) a different size PV was placed eventually. Recapturing or repositioning of the PV, because of suboptimal positioning of the initially implanted device, was performed in 27.9% of the treatments. Additional coiling was performed in 18.6% for the following reasons: large size (46.2%), operator’s choice (30.8%), acute pre-interventional aneurysmal hemorrhage (7.7%), and irregular shape (7.7%). In-stent balloon angioplasty was performed to enhance the vessel wall apposition in 24.6%.
The ease of deployment was rated ‘good’ or ‘very good’ in 88.5% of the cases, while in 6.6% it was rated ‘intermediate’, and ‘poor’ in only 4.9%. Vessel wall apposition was rated ‘very good’ or ‘good’ in 95.1% and ‘intermediate’ in 4.9%, while it was not rated ‘poor’or ‘very poor’ in any case. In 91.8%, the radiopacity of the PV was rated ‘good’ or ‘very good’. Comparing the PV with the Pipeline Flex with Shield Technology, it was rated ‘better’ in 52.5%, ‘slightly better’ in 8.2%, and ‘equivalent’ in 34.4%. It was rated ‘slightly worse’ in 4.9% but it was never rated ‘worse’.
The immediate post-interventional occlusion rates were as follows: OKM A1 in 17.1%, A2 in 31.4%, A3 in 17.1%, B1 in 1.4%, B2 in 8.6%, B3 in 14.3%, C1, C2 and C3 in 1.4%, respectively, and D in 5.7%.
Adverse events and complications
Procedural technical complications occurred in 15 out of 61 treatments (24.6%). The most frequent technical complication (12/15; 19.7% of all treatments) was hang-up of the FD on the pusher wire at the proximal part of the interface between the FD and the pusher wire, so that the FD could not be released as intended. In all of these cases, the FD could be finally released by applying repetitive gentle push and/or pull on the pusher wire. In four cases, the hang-up was severe, so that several attempts and more force were necessary to release the FD. In one of these cases, during the treatment of an 11 mm sidewall aneurysm of the ICA, this manipulation led to a pull back of the PV at the level of the neck of the aneurysm, so that a second PV of the same size had to be placed. In another treatment, without hang-up of the FD, there was insufficient vessel wall apposition at the proximal part of the PV and a Neuroform Atlas stent (Stryker Neurovascular, Fremont, CA) was additionally implanted to improve the apposition. The other technical complications were displacement of the FD when navigating the microcatheter through it, and a high resistance when pushing the FD through the microcatheter which led to breaking of the proximal part of the microcatheter. All of these technical complications were successfully managed and did not cause any clinical consequences. No periprocedural thrombotic complications occurred.
A non-device related procedural symptomatic complication, an anaphylactic allergic reaction, occurred in one treatment (1.6%) and was successfully overcome with medical treatment.
After one treatment (1.6%), the control angiography at 9 months showed the PV was completely occluded, despite the patient being asymptomatic during the entire follow-up period. No apparent reason could be found for the stent occlusion.
Post-procedural symptomatic complications occurred after four treatments (6.6%), of which only one was directly related to the implanted FD. One patient developed small brain stem and midbrain infarctions, most likely due to the occlusion of perforator arteries, after the implantation of five PVs into the basilar and posterior cerebral artery for the treatment of a multisegmental aneurysmal disease, leading to a stroke (National Institutes of Health Stroke Scale (NIHSS) 5). This patient was on dual antiplatelet therapy using ASA and clopidogrel, and additionally received enoxaparin at prophylactic dose for anticoagulation. One patient who was treated in the acute stage of a severe subarachnoid hemorrhage died after an uneventful PV placement, due to the consequences of the previous subarachnoid hemorrhage. The two other complications were a puncture site bleeding which needed surgical intervention and a urinary tract infection during the hospital stay which resolved after administration of antibiotics.
Clinical follow-up
The mean clinical follow-up period was 6.6±3.1 months. One patient died during the follow-up (see section ‘Adverse events and complications’). The mRS at the latest follow-up was 0.5±1.0 (mRS 0 in 44 patients (73.3%), mRS 1 in 12 patients (20.0%), mRS 3 in three patients (5.0%), and mRS 6 in one patient (1.7%). Deterioration of mRS (compared with the pre-interventional scale) was observed in two patients: in the patient who developed a stroke due to perforator artery infarctions (mRS 3 at the 1 year follow-up), and in the patient who died.
Imaging follow-up and aneurysm occlusion
The mean imaging follow-up period was 7.1±2.3 months. Imaging follow-up was available for 58/60 (96.7%) patients and for 68/70 (97.1%) aneurysms. No imaging was available for a patient who suffered from a severe contrast agent allergy (the same patient who developed an anaphylactic allergic reaction during the treatment) and for the patient who died. The imaging modality was invasive catheter angiography in 74.1%, magnetic resonance imaging (MRI) in 22.4%, and computed tomography (CT) in 3.4%.
In-stent stenosis or occlusion was observed after 13 treatments (21.3%) and was graded as ‘mild’ in 12/13 cases (92.3%). No moderate or severe in-stent stenosis was observed. In one case (1.6%), a complete, asymptomatic occlusion of a PV implanted into the MCA for the treatment of a fusiform MCA bifurcation aneurysm, which was completely occluded in the follow-up imaging, was observed.
Regarding all aneurysms treated with the PV, at the latest imaging follow-up, the rate of adequate occlusion was 95.5% and the rate of complete occlusion was 77.9% (mRROC I in 77.9%, II in 17.6%, and III, IIIa and IIIb in 1.5%, respectively). Regarding only cases in which no additional coiling of the aneurysm was performed, the rates of adequate and complete occlusion were 94.6% and 76.8%, respectively (mRROC I in 76.8%, II in 17.9%, and III in 5.4%).
Of the 34 aneurysms with integrated branches into the aneurysm sac, 82.4% were completely occluded in the latest follow-up imaging. For these aneurysms, the CSC classification was class 1A (full patency of the integrated branch) in 38.2%, class 1B (branch reduced in caliber) in 29.4%, class 1C (no antegrade filling of the branch) in 14.7%, and classes 2, 3 and 5 in 5.9%, respectively. The caliber reductions (CSC 1B) and the occlusions of the side branches (CSC 1C) were without clinical symptoms in all patients and without any infarction in follow-up imaging (only assessable in cases in which MRI or CT was performed).
Discussion
In this study, comprising the multicenter experience of 10 international centers, the safety, feasibility and efficacy of the new PV FD for the treatment of intracranial aneurysms were demonstrated.
The major innovations of the new PV are the DFT structure of the wires, the smaller diameters of the wires, and the higher pore density of the 64-wire implants. It is assumed that the DFT structure, which is also applied in other newer stents for aneurysm treatments, such as the Derivo embolization device (Acandis, Pforzheim, Germany) or the Silk Vista (Balt, Montmorency, France), may improve the opening characteristics of the stent. The smaller diameter of the wires provides a lower overall thickness of the device. This feature can potentially lower the risk of early thrombotic complications and improve endothelialization of the stent, which may lower the risk of subacute thrombotic complications and of exuberant intimal hyperplasia. The higher pore density aims to improve the rate of aneurysm occlusion by a higher flow diverting effect, lowering the inflow, and consequently enhancing stasis within the aneurysm.
One preclinical study, published by Starke et al in 2020, evaluated the safety and efficacy of the PV in an in vivo animal model and by using a human blood flow loop in an in vitro model.17 In this experimental study, the PV improved the aneurysm occlusion and the implant endothelialization, and provided a significantly lower thrombogenicity, compared with the Pipeline Flex with Shield Technology, while preserving the biocompatibility safety profile of its predecessor.
This is the first clinical study reporting on the new PV. Our findings indicate that the PV is safe, feasible, and the short-term follow-up occlusion results are promising. Nearly all interventionalists rated the overall performance of the PV as equivalent (34.4%) or (slightly) better (60.7%) compared with its precursor device. However, since there was no direct comparison device, no conclusive statement regarding the superiority of the PV over other FDs can be made on the basis of this work.
The rate of symptomatic complications was relatively low in our study, with an overall symptomatic complication rate of 8.2% and a neurological symptomatic complication rate of 3.3%. Of these complications, only one was directly related to the FD (1.6%; infarctions due to the coverage of perforator arteries by the FD). Another FD-related complication was a complete stent occlusion in the follow-up imaging, which was asymptomatic. However, the rate of technical procedural complications was relatively high. Most of these technical complications involved a hang-up of the FD on the pusher wire (80.0% of all technical procedural complications; 19.7% of all PV treatments). Luckily, in all but one case, in which an additional FD had to be placed, this technical complication did not lead to further adverse events which required additional treatment, and in all cases these events did not cause any clinical consequence and were asymptomatic. According to the manufacturer, this phenomenon was caused by a hang-up of the struts of the FD at a gearwheel-like plate at the proximal portion of the interface between the FD and the pusher wire. The version of the PV which had been evaluated in this study was revised to address this issue, including the addition of small silicon plates adjacent to these gearwheel-like plates, which are preventing a hang-up of the FD during the deployment of the device. These adverse events and complication rates are in line with results reported in the literature for the older Pipeline versions and for other FDs.6 9 12 17–19 In this regard, it is noteworthy to mention that in our study a comparatively larger number of treated aneurysms were located more distally, such as in the MCA, the ACOM or the ACA distal to the ACOM, locations which are known to be more prone to complications. In a meta-analysis, analyzing complications associated with the use of FDs and comprising data of 3125 patients, the overall complication rate was 17.0% and the neurological morbidity rate was 4.5%.
In our study, balloon angioplasty was performed to enhance the vessel wall apposition of the stent in 24.6%, which is slightly higher than the rates reported in the literature. The rate of adjunctive balloon angioplasties was 22.0% in the PREMIER study,18 and it was 16.8% in the Pipeline for Uncoilable or Failed Aneurysms (PUFs) trial.12 No specific reasons for this slightly increased rate of balloon angioplasty were found in our work.
The rate of complete aneurysm occlusion in our study was 77.9% after a mean follow-up period of 7.1 months. This rate is comparable with rates which were published for earlier versions of the PED and other FDs. In a meta-analysis which included 1451 patients with 1654 aneurysms, treated with different FDs, the complete occlusion rate was 76.0%.4 In the PUFs trial, the rate of complete aneurysm occlusion after PED treatment at 180 days was 73.6%,12 reaching 95.2% at 5 years in a subsequent study.20 When comparing these rates, the differences in patient populations, aneurysm characteristics (eg, relatively large aneurysms in the PUFs trial), and treatment techniques (eg, frequency of additional coiling) have to be taken into consideration.
We acknowledge that this study has several noteworthy limitations. This work is a retrospective, observational study, which is based on a dedicated survey that was completed by the treating interventionalists themselves. There were no additional data or imaging analysis by an independent core lab. Furthermore, some of the assessed treatment parameters were subjectively rated by the interventionalists. These factors lead to an inherent selection and reporting bias associated with this study. Furthermore, the number of cases in this study is relatively small, the data are quite heterogeneous (eg, patients treated with and without additional coiling), and a control group is lacking. However, this is a multicenter study and, to our knowledge, the only study reporting on the clinical use of the PV to date. Since the PV was introduced only recently, no long-term follow-up data are available for this study. The interventions were performed in a few high-volume centers carefully selected by the manufacturer in a limited market release. The results may vary when the device is available freely to other centers. Another limitation is that the version of the PV which was evaluated in this study was subsequently slightly modified, especially small changes to the pusher wire (to prevent a hang-up with the FD, explained in more detail above), compared with the device which is now commercially available.
Conclusions
The new PV FD is safe and feasible for the treatment of intracranial aneurysms. The short-term occlusion rates are promising but need further evaluation in prospective long-term follow-up studies. Further studies, preferably with a prospective design and an independent imaging lab, are warranted to evaluate treatment with the new PV.
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by the Ethics Committee of the University of Heidelberg (S-247/2009). Participants gave informed consent to participate in the study before taking part.
References
Footnotes
Twitter @pedrovegavaldes, @Doctorgaldamez, @VitorMendesPer1
Contributors All listed authors contributed to the work. DFV and MAM acquired, analyzed, and interpreted data for the work; designed the study; drafted the manuscript and approved the final manuscript. DFV and MAM are guarantors of this work. IS and MB acquired, analyzed, and interpreted data for the work; drafted the manuscript and approved the final manuscript. SC, FB, BO, OK, RR, MS, AT, PV, MMG, JL and VMP acquired and analyzed data for the work and approved the final manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests DFV has received travel support outside this work from MicroVention and Stryker GmbH & Co. KG. SC is shareholder of NDI Technologies and Vesalio LLC, non-paid member of Siemens Senior Advisory Board, and reports consultancy proctorship agreements with Medtronic and MicroVention. IS reports consultancy and proctorship agreements with Medtronic and MicroVention, and is Associate Editor for JNIS. RR is consultant for Stryker Neurovascular, Medtronic, MicroVention and Acandis. MMG is consultant and proctor for Medtronic. VMP is consultant for Medtronic. MB reports board membership: DSMB Vascular Dynamics; consultancy: Roche, Guerbet, Codman; grants/grants pending: DFG, Hopp Foundation, Novartis, Siemens, Guerbet, Stryker, Covidien; payment for lectures (including service on speakers bureaus): Novartis, Roche, Guerbet, Teva, Bayer, Codman. MM has received consulting honoraria, speaker honoraria, and travel support outside this work from Codman, Covidien/Medtronic, MicroVention, Phenox, and Stryker.
Provenance and peer review Not commissioned; externally peer reviewed.