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Background The Woven EndoBridge (WEB) device was explicitly designed for wide-neck intracranial bifurcation aneurysms. Small-scale reports have evaluated the off-label use of WEB devices for the treatment of sidewall aneurysms, with promising outcomes. Purpose To compare the angiographic and clinical outcomes of the WEB device for the treatment of sidewall aneurysms compared with the treatment of bifurcation aneurysms. Materials and Methods A retrospective review of the WorldWideWEB Consortium, a synthesis of retrospective databases spanning from January 2011 to June 2021 at 22 academic institutions in North America, South America, and Europe, was performed to identify patients with intracranial aneurysms treated with the WEB device. Characteristics and outcomes were compared between bifurcation and sidewall aneurysms. Propensity score matching (PSM) was used to match by age, pretreatment ordinal modified Rankin Scale score, ruptured aneurysms, location of aneurysm, multiple aneurysms, prior treatment, neck, height, dome width, daughter sac, and incorporated branch. Results A total of 683 intracranial aneurysms were treated using the WEB device in 671 patients (median age, 61 years [IQR, 53-68 years]; male-to-female ratio, 1:2.5). Of those, 572 were bifurcation aneurysms and 111 were sidewall aneurysms. PSM was performed, resulting in 91 bifurcation and sidewall aneurysms pairs. No significant difference was observed in occlusion status at last follow-up, deployment success, or complication rates between the two groups. Conclusion No significantly different outcomes were observed following the off-label use of the Woven EndoBridge, or WEB, device for treatment of sidewall aneurysms compared with bifurcation aneurysms. The correct characterization of the sidewall aneurysm location, neck angle, and size is crucial for successful treatment and lower retreatment rate. © RSNA, 2022 See also the editorial by Hetts in this issue.

Background and purpose Previous studies suggest that mechanisms and outcomes in patients with COVID-19-associated stroke differ from those in patients with non-COVID-19-associated strokes, but there is limited comparative evidence focusing on these populations. The aim of this study, therefore, was to determine if a significant association exists between COVID-19 status with revascularization and functional outcomes following thrombectomy for large vessel occlusion (LVO), after adjustment for potential confounding factors. Methods A cross-sectional, international multicenter retrospective study was conducted in consecutively admitted COVID-19 patients with concomitant acute LVO, compared to a control group without COVID-19. Data collected included age, gender, comorbidities, clinical characteristics, details of the involved vessels, procedural technique, and various outcomes. A multivariable-adjusted analysis was conducted. Results In this cohort of 697 patients with acute LVO, 302 had COVID-19 while 395 patients did not. There was a significant difference (p < 0.001) in the mean age (in years) and gender of patients, with younger patients and more males in the COVID-19 group. In terms of favorable revascularization (modified Thrombolysis in Cerebral Infarction [mTICI] grade 3), COVID-19 was associated with lower odds of complete revascularization (odds ratio 0.33, 95% confidence interval [CI] 0.23-0.48; p < 0.001), which persisted on multivariable modeling with adjustment for other predictors (adjusted odds ratio 0.30, 95% CI 0.12-0.77; p = 0.012). Moreover, endovascular complications, in-hospital mortality, and length of hospital stay were significantly higher among COVID-19 patients (p < 0.001). Conclusion COVID-19 was an independent predictor of incomplete revascularization and poor functional outcome in patients with stroke due to LVO. Furthermore, COVID-19 patients with LVO were more often younger and had higher morbidity/mortality rates.

Endovascular treatment of cervical internal carotid artery (ICA) loop dissections in acute stroke interventions can be challenging. Flow diverters can effectively reconstruct vessel loops and treat the injured vessel and provide a safe conduit for intracranial catheterization.We retrospectively reviewed our neurointerventional database and identified all patients with ICA loop dissections treated with flow diverters in the acute setting between August 2016 and September 2020. Patient demographics, procedural data, imaging follow-up results, and clinical outcome information were collected.Seven patients with a mean age of 62 years (range: 43-85 years) who underwent reconstruction of an ICA (loop) dissection with flow diverters were included. Four ICA dissections were treated with the Surpass Streamline flow diverter and 3 with the Pipeline embolization device. All cases were technically successful. All stroke cases achieved intracranial flow ≥thrombolysis in cerebral infarction 2B. Observed intracranial hemorrhages were all asymptomatic. All cases showed patent flow diverter(s) with or without (carotid) stent(s) on follow-up imaging. Semielectively treated patients did not show a change from baseline modified Rankin scale related to the procedure. Patients with acute stroke had a modified Rankin scale ≤2 in 4 of 5 cases (80%) at 3 months. Two patients died due to medical issues unrelated to the procedures. No patient showed new or recurrent symptoms.Use of flow diverters, in some cases in conjunction with (carotid) stents, is an effective treatment option for cervical carotid artery (loop) dissections.

BackgroundPlatelets and von Willebrand factor (vWF) are key components of acute ischemic stroke (AIS) emboli. We aimed to investigate the CD42b (platelets)/vWF expression, its association with stroke etiology and the impact these components may have on the clinical/procedural parameters.MethodsCD42b/vWF immunostaining was performed on 288 emboli collected as part of the multicenter STRIP Registry. CD42b/VWF expression and distribution were evaluated. Student’s t-test and χ2test were performed as appropriate.ResultsThe mean CD42b and VWF content in clots was 44.3% and 21.9%, respectively. There was a positive correlation between platelets and vWF (r=0.64, pConclusionsThe vWF level and CD42b/vWF distribution pattern in emboli were correlated with AIS etiology and revascularization outcome. Platelet content was associated with response to thrombolysis.

Introduction Direct aspiration thrombectomy of proximal anterior circulation large vessel occlusions (LVOs) with super‐bore catheters (SBCs, 0.088” ID) may result in improved first pass success, though their consistent delivery to the target occlusion remains challenging. We report the first‐in‐human experience with a novel full‐length 132 cm 0.088” ID FreeClimb ® 88 catheter (Route 92 Medical, San Mateo, CA, currently approved for neurovascular access), and its customized Tenzing ® 8 delivery catheter, for anterior circulation LVO acute stroke patients. Methods We performed a retrospective review of thrombectomy cases for proximal anterior circulation large vessel occlusions performed at three stroke centers from May 2022 through August 2022. All patients were treated using the Route 92 Medical 8F Base Camp® guide catheter, FreeClimb ® 88 catheter and Tenzing ® 8 delivery catheter in an off‐label fashion. Results Ten consecutive acute stroke patients with anterior circulation LVOs were treated. The median age was 71 (45‐91) and 6 were female (60%). The median presenting NIHSS score and ASPECT score were 17 (8‐24) and 9 (6‐10), respectively. LVO locations were as follows: two right carotid termini, three right M1 middle cerebral arteries, and five left M1 middle cerebral arteries. Three patients also had tandem occlusion/near‐occlusion of the respective cervical internal carotid artery. The FC88 catheter was delivered to the target occlusion with 100% success. The median time from groin puncture to catheter delivery to the target occlusion was 14 minutes (7‐35). First pass complete reperfusion (modified Thrombolysis in Cerebral Infarction score, mTICI, of 3) was achieved in 9/10 (90%) patients (self‐adjudicated). Adjunctive therapy for a residual M2 occlusion was utilized in 1/10 patients. There were no adverse events or post‐procedural symptomatic hemorrhages. Conclusions Our first‐in‐human experience with a novel 132 cm full‐length super‐bore catheter (Route 92 FreeClimb ® 88 catheter) and its customized catheter delivery device (Tenzing ® 8) for aspiration thrombectomy of proximal anterior circulation large vessel occlusions demonstrated 100% successful delivery to the target occlusion, with TICI 3 first pass reperfusion achieved in 90% of patients.

Introduction In the last several years,there has been a paradigm shift in treating patients presenting with large vessel occlusion (LVO) strokes with endovascular therapy (EVT). Currently, the 24‐hour window has been incorporated in acute stroke management guidelines based on trials supporting the selection of patients with evidence of ischemic penumbra on perfusion imaging1,2. No current randomized control trials exist to support very late window EVT (beyond 24 hours) from last seen well (LSW) and its benefits are unknown. Several retrospective studies showed that EVT is safe and feasible up to 6 days from LSW in selected patients who are able preserve a favorable ischemic core to penumbra3, 4, 5. In this study we present a retrospective review of three patients with LVO strokes of the anterior circulation successfully treated between 10–14 days from LSW. We aim to explore the safety, efficiency and positive predictors of very late window EVT. Methods A single center retrospective review of stroke patients was performed. 517 patients with LVO strokes who underwent EVT between January 2018 and December 2021 were screened. 3 patients were found to have EVT performed 24 hours beyond LSW. Patient demographics, characteristics and clinical information were collected by systematic chart review. The primary outcome was functional independence as assessed by the modified Rankin Score (mRS) at 90 days. The safety outcomes included neurological deterioration and symptomatic intracranial hemorrhage, defined as an increase in National Institutes of Health Stroke Scale (NIHSS) of 4 or more). Further, a comprehensive literature review of studies describing very late window EVT cases indexed in PubMed was performed. Results We identifiedthree patients with LVO strokes, treated more than 24 hours from LSW. Patient ages ranged from 75 to 89 years. Baseline NIHSS ranged from 1 to 13. All patients had LVO or stenosis of the anterior circulation (internal carotid artery and/or M1 segment of the middle cerebral artery). All patients had fluctuation in their symptoms with worsening going from a supine position to a sitting position, evidence of ischemic penumbra on perfusion imaging and slow infarct growth on repeat brain imaging. The time from LSW to intervention ranged from 11 to 14 days. Recanalization score ranged from 2B‐3. No patients had intracranial hemorrhage or neurological decline. mRS scores were 2, 4, and 6 at 3 months. The patient who died had preservation of neurological function but died in the hospital due to heart failure. Conclusions We conclude that widening of the EVT time window presents new opportunities to treat a select population of LVO stroke patients. To our knowledge, there are no other reports of EVT in LVO patients beyond 10 days of LSW. Patients who have evidence of large ischemic penumbra, fluctuation of symptoms with change in position or blood pressure, good collateral circulation, and small infarct core that grows slowly on repeat imaging may be reasonable candidates for delayed EVT. More data are needed to inform clinical practice.

Introduction EXCELLENT (NCT03685578; Cerenovus) is a large, prospective, international, real‐world registry of endovascular clot removal in acute ischemic stroke (AIS) with EmboTrap as the first line mechanical thrombectomy (MT) device, which included collection and analysis of the retrieved thrombus material. Methods Between September 2018 and March 2021, 1000 “all‐comer” patients were enrolled at 34 global sites (27 US, 5 EU, 1 UK, 1 Israel) and treated according to standard of care at each center (with Embrotrap as first line). The study employed blind endpoint evaluation, including a core imaging lab and an independent 90‐day mRS assessment. Retrieved clot was collected per each MT maneuver from 538 subjects across 26 sites and clot analysis was performed by independent central labs blinded to clinical data. Results mITT population included 998 subjects. Mean age was 69.9±14.18 years (range 18–102), 51.8% (517/998) subjects were female and 9.9% (97/997) had a pre‐stroke mRS 3–5. Baseline NIHSS was 15.6±6.87 (range 0–36); 10.1% (82/815) subjects had a large core (ASPECTS 0–5); 5.8% (57/990) had posterior stroke; 56.3% (523/929) underwent MT ≤ 6hrs of onset and 38.1% (380/998) received IV‐tPA prior to MT. First pass eTICI 2c‐3 was achieved in 38.3% (377/984) and final 2b‐3 in 94.5 % (930/984; median number of passes = 1) of subjects. 90‐day mRS≤2 or ≤pre‐stroke was 46.9% (429/915) and 90‐day all‐cause mortality was 19.0% (175/921). The univariate analysis of clot components showed high red blood cell and low platelet content were significant predictors of good mRS outcome (p Conclusions This large multi‐center, all‐comer cohort reflects the population undergoing thrombectomy today in a real world‐setting. Final angiographic, clinical and thrombus composition results, along with multivariate analysis of predictors of clinical outcomes, will be presented at the time of the conference.

Background: Understanding clot composition may allow for better technical planning and improved outcomes in mechanical thrombectomy (MT). We sought to correlate clot composition with reperfusion outcomes in MT. Methods: Clinical, imaging, and clot data from patients enrolled in the STRIP Registry from September 2016 to September 2020 were analyzed. Samples were fixed in 10% phosphate-buffered formalin and stained with hematoxylin and eosin and Martius Scarlett Blue. Percent composition, richness, and gross appearance were evaluated. Outcome measures included the rate of First-Pass Effect (mTICI2c/3, FPE) and the number of device passes. Results: A total of 1430 patients (mean age, 68.4±13.5years; median [IQR] baseline NIHSS,17.2 [10.5-23]; IV-tPA use, 36%; Stent-Retrievers [SR], 27%; Contact Aspiration [CA], 27%; Combined SR + CA, 43%) were included. The median [IQR] number of passes was 1 [1-2]. FPE was achieved in 39.3% of the cases. There was no association between percent histological composition or clot richness and FPE in the overall population. However, the combined technique resulted in lower FPE rates for RBC-rich (P Conclusion: Despite the lack of correlation between clot histology and FPE in the overall population, our study adds to the growing body of evidence supporting the notion that clot composition influences reperfusion treatment strategy outcomes. Additional studies are needed.

Introduction: EXCELLENT (NCT03685578) is a global prospective, multicenter, real-world registry of mechanical thrombectomy for stroke with the EmboTrap device as first line treatment which includes clot collection and analysis. Aim of the study: To report the rates of clinical outcomes and clot characteristics associated with first pass reperfusion in EXCELLENT. Methods: Per pass angiographic outcomes assessed by an independent core lab were available in 984 subjects Analysis of clot from 538 cases was performed by independent central labs blinded to clinical data. 90-day mRS assessment was blinded to subject data. Results: First pass reperfusion of mTICI 2b-3 (63.2%) and 2c-3 (38.3%) was significantly predictive of mRS 0-2 or ≤pre-stroke (p=0.011 and p=0.016) but not all-cause mortality at 90 days (p=0.080 and p=0.123, respectively). Further, mTICI 2c-3 in one pass was associated with a higher rate of mRS 0-2 or ≤pre-stroke vs. mTICI 2c-3 reperfusion in >1 pass, (55.5% and 45.1%, respectively, p=0.013) and a rate of all-cause mortality at 90 days of 14.6% vs. 19.8% (p=0.097). Full patient characteristics and clinical outcomes are shown in Table 1. Notable clot composition findings included: RBC (%, mean±SD): mTICI 2c-3, 1 pass 47.69±22.25, mTICI 2c-3, >1 pass 43.86±19.05, (p=0.088); fibrin: mTICI 2c-3, 1 pass 23.20±13.80, mTICI 2c-3 >1 pass 25.40 ± 13.52 (p=0.131); von Willebrand factor (VWF): mTICI2c-3, 1 pass 16.09±14.62, mTICI 2c-3, >1 pass 19.42±17.15 (p=0.038). Conclusions: First pass reperfusion in the EXCELLENT registry was associated with better clinical outcomes at 90 days. Clots retrieved with first pass reperfusion had higher RBC and lower fibrin and VWF content compared to those who achieved reperfusion at greater than one pass.

BackgroundThe pipeline embolization device (PED; Medtronic) has presented as a safe and efficacious treatment for small- and medium-sized intracranial aneurysms. Independently adjudicated long-term results of the device in treating these lesions are still indeterminate. We present 3-year results, with additional application of a flow diverter specific occlusion scale.MethodsPREMIER (prospective study on embolization of intracranial aneurysms with pipeline embolization device) is a prospective, single-arm trial. Inclusion criteria were patients with unruptured wide-necked intracranial aneurysms ≤12 mm. Primary effectiveness (complete aneurysm occlusion) and safety (major neurologic event) endpoints were independently monitored and adjudicated.ResultsAs per the protocol, of 141 patients treated with a PED, 25 (17.7%) required angiographic follow-up after the first year due to incomplete aneurysm occlusion. According to the Core Radiology Laboratory review, three (12%) of these patients progressed to complete occlusion, with an overall rate of complete aneurysm occlusion at 3 years of 83.3% (115/138). Further angiographic evaluation using the modified Cekirge–Saatci classification demonstrated that complete occlusion, neck residual, or aneurysm size reduction occurred in 97.1%. The overall combined safety endpoint at 3 years was 2.8% (4/141), with only one non-debilitating major event occurring after the first year. There was one case of aneurysm recurrence but no cases of delayed rupture in this series.ConclusionsThe PED device presents as a safe and effective modality in treating small- and medium-sized intracranial aneurysms. The application of a flow diverter specific occlusion classification attested the long-term durability with higher rate of successful aneurysm occlusion and no documented aneurysm rupture.Trial registrationNCT02186561.

BackgroundThe micro-architectonics of the subarachnoid space (SAS) remain partially understood and largely ignored, likely the result of the inability to image these structures in vivo. We explored transvascular imaging with high-frequency optical coherence tomography (HF-OCT) to interrogate the SAS.MethodsIn vivo HF-OCT was performed in 10 dogs in both the posterior and anterior cerebral circulations. The conduit vessels used were the basilar, anterior spinal, and middle and anterior cerebral arteries through which the perivascular SAS was imaged. The HF-OCT imaging probe was introduced via a microcatheter and images were acquired using a contrast injection (3.5 mL/s) for blood clearance. Segmentation and three-dimensional rendering of HF-OCT images were performed to study the different configurations and porosity of the subarachnoid trabeculae (SAT) as a function of location.ResultsOf 13 acquisitions, three were excluded due to suboptimal image quality. Analysis of 15 locations from seven animals was performed showing six distinct configurations of arachnoid structures in the posterior circulation and middle cerebral artery, ranging from minimal presence of SAT to dense networks and membranes. Different locations showed predilection for specific arachnoid morphologies. At the basilar bifurcation, a thick, fenestrated membrane had a unique morphology. SAT average thickness was 100 µm and did not vary significantly based on location. Similarly, the porosity of the SAT averaged 91% and showed low variability.ConclusionWe have demonstrated the feasibility to image the structures of the SAS with transvascular HF-OCT. Future studies are planned to further map the SAT to increase our understanding of their function and possible impact on neurovascular pathologies.

BackgroundCompositional and structural features of retrieved clots by thrombectomy can provide insight into improving the endovascular treatment of ischemic stroke. Currently, histological analysis is limited to quantification of compositions and qualitative description of the clot structure. We hypothesized that heterogeneous clots would be prone to poorer recanalization rates and performed a quantitative analysis to test this hypothesis.MethodsWe collected and did histology on clots retrieved by mechanical thrombectomy from 157 stroke cases (107 achieved first-pass effect (FPE) and 50 did not). Using an in-house algorithm, the scanned images were divided into grids (with sizes of 0.2, 0.3, 0.4, 0.5, and 0.6 mm) and the extent of non-uniformity of RBC distribution was computed using the proposed spatial heterogeneity index (SHI). Finally, we validated the clinical significance of clot heterogeneity using the Mann–Whitney test and an artificial neural network (ANN) model.ResultsFor cases with FPE, SHI values were smaller (0.033 vs 0.039 for grid size of 0.4 mm, P=0.028) compared with those without. In comparison, the clot composition was not statistically different between those two groups. From the ANN model, clot heterogeneity was the most important factor, followed by fibrin content, thrombectomy techniques, red blood cell content, clot area, platelet content, etiology, and admission of intravenous tissue plasminogen activator (IV-tPA). No statistical difference of clot heterogeneity was found for different etiologies, thrombectomy techniques, and IV-tPA administration.ConclusionsClot heterogeneity can affect the clot response to thrombectomy devices and is associated with lower FPE. SHI can be a useful metric to quantify clot heterogeneity.

BackgroundData regarding the safety and efficacy of flow diverting stents (FDS) in the treatment of middle cerebral artery (MCA) bifurcation aneurysms are scarce and limited to small single center series, with particular concern for increased risk of ischemic complications with jailing one of the M2 branches.MethodsProspectively-maintained databases at six North American and European centers were queried for patients harboring MCA bifurcation aneurysms undergoing treatment with FDS (2011–2018). The pertinent clinical and radiographic data were collected and analyzed.Results87 patients (median age 60 years, 69% females) harboring 87 aneurysms were included. The majority of aneurysms were unruptured (79%); 75.9% were saccular with a median maximal diameter of 8.5 mm. Radiographic imaging follow-up was available in 88.5% of cases at a median of 16.3 months post-treatment, showing complete occlusion in 59% and near complete occlusion (90–99%) in 18% of aneurysms. The overall rate of ischemic and hemorrhagic complications was 8% and 1.1%, respectively. Symptomatic and permanent complications were encountered in 5.7% and 2.3% of patients respectively, with retreatment pursued in 2.3% of patients. Jailed branch occlusion was detected in 11.5% of cases, with clinical sequelae in 2.3%. Last follow-up modified Rankin Scale of 0–2 was noted in 96.8% of patients. On multivariate analysis, male sex was the only independent predictor of aneurysmal persistence at last follow-up imaging (p=0.019).ConclusionFDS treatment for MCA bifurcation aneurysms is feasible, with comparable safety and efficacy profiles to other available endovascular options when utilized in carefully selected aneurysms. Jailing of M2 branches was not associated with a higher risk of post-procedural ischemic complications.

We describe a novel technique of vein of Labbé preservation using balloon protection during embolisation of a transverse-sigmoid sinus dural arteriovenous fistula. A patient with refractory Cognard type IV fistula of the left transverse-sigmoid sinus and persistent pulsatile tinnitus underwent successful embolisation of the lesion via transarterial route. During embolisation, a dual lumen balloon was simultaneously inflated within the vein of Labbé, at its orifice in the transverse-sigmoid sinus junction, to prevent embolic reflux. This allowed for liquid embolic embolisation of the fistula via the transarterial route resulting in complete occlusion. The patient recovered well with marked improvement of his tinnitus.

Background and ObjectivesCurrent guidelines do not address recommendations for mechanical thrombectomy (MT) in the extended time window (>6 hours after time last seen well [TLSW]) for large vessel occlusion (LVO) patients with preexisting modified Rankin Scale (mRS) > 1. In this study, we evaluated the outcomes of MT vs medical management in patients with prestroke disability presenting in the 6- to 24-hour time window with acute LVO.MethodsWe analyzed a multinational cohort (61 sites, 6 countries from 2014 to 2020) of patients with prestroke (or baseline) mRS 2 to 4 and anterior circulation LVO treated 6–24 hours from TLSW. Patients treated in the extended time window with MT vs medical management were compared using multivariable logistic regression and inverse probability of treatment weighting (IPTW). The primary outcome was the return of Rankin (ROR, return to prestroke mRS by 90 days).ResultsOf 554 included patients (448 who underwent MT), the median age was 82 years (interquartile range [IQR] 72–87) and the National Institutes of Health Stroke Scale (NIHSS) was 18 (IQR 13–22). In both MV logistic regression and IPTW analysis, MT was associated with higher odds of ROR (adjusted OR [aOR] 3.96, 95% CI 1.78–8.79 and OR 3.10, 95% CI 1.20–7.98, respectively). Among other factors, premorbid mRS 4 was associated with higher odds of ROR (aOR, 3.68, 95% CI 1.97–6.87), while increasing NIHSS (aOR 0.90, 95% CI 0.86–0.94) and decreasing Alberta Stroke Program Early Computed Tomography Scale score (aOR per point 0.86, 95% CI 0.75–0.99) were associated with lower odds of ROR. Age, intravenous thrombolysis, and occlusion location were not associated with ROR.DiscussionIn patients with preexisting disability presenting in the 6- to 24-hour time window, MT is associated with a higher probability of returning to baseline function compared with medical management.Classification of EvidenceThis investigation's results provide Class III evidence that in patients with preexisting disability presenting 6–24 hours from the TLSW and acute anterior LVO stroke, there may be a benefit of MT over medical management in returning to baseline function.

IntroductionThe Walrus balloon guide catheter (BGC) is a new generation of BGC, designed to eliminate conventional limitations during mechanical thrombectomy.ObjectiveTo report a multi-institutional experience using this BGC for proximal flow control (PFC) in the setting of carotid artery angioplasty/stenting (CAS) in elective (eCAS) and tandem strokes (tCAS).MethodsProspectively maintained databases at 8 North American centers were queried to identify patients with cervical carotid disease undergoing eCAS/tCAS with a Walrus BGC.Results110 patients (median age 68, 64.6% male), 80 (72.7%) undergoing eCAS and 30 (27.3%) tCAS procedures, were included (median cervical carotid stenosis 90%; 46 (41.8%) with contralateral stenosis). Using a proximal flow-arrest technique in 95 (87.2%) and flow-reversal in 14 (12.8%) procedures, the Walrus was navigated into the common carotid artery successfully in all cases despite challenging arch anatomy (31, 28.2%), with preferred femoral access (103, 93.6%) and in monitored anesthesia care (90, 81.8%). Angioplasty and distal embolic protection devices (EPDs) were used in 91 (83.7%) and 58 (52.7%) procedures, respectively. tCAS led to a modified Thrombolysis in Cerebral Infarction 2b/3 in all cases. Periprocedural ischemic stroke (up to 30 days postoperatively) rate was 0.9% (n=1) and remote complications occurred in 2 (1.8%) cases. Last follow-up modified Rankin Scale score of 0–2 was seen in 95.3% of eCAS cohort, with no differences in complications in the eCAS subgroup between PFC only versus PFC and distal EPD (median follow-up 4.1 months).ConclusionWalrus BGC for proximal flow control is safe and effective during eCAS and tCAS. Procedural success was achieved in all cases, with favorable safety and functional outcomes on short-term follow-up.

BackgroundPreclinical testing of intracranial stents is currently performed in the peripheral circulation, and rarely in the basilar artery of the dog.ObjectiveTo test the feasibility of intracranial stenting in the middle cerebral artery (MCA) of the dog and explore the use of MRI to detect thromboembolic complications.MethodsSix purpose-bred cross-hound dogs were used for proof-of-concept stenting of both MCAs in each animal. Immediately following the procedure, the animals were imaged with MRI. MRI was repeated weekly for 1 month. After the final angiography at 30 days, the animals were euthanized for pathological assessment of the stents and the brain.ResultsWe successfully deployed 12 stents in the MCAs of all animals. We deployed three techniques for microcatheterization of the MCA—namely, directly through the internal carotid artery (ICA), using anastomotic arteries from the external carotid artery, or via the contralateral ICA through the anterior communicating artery. Two iatrogenic perforations of the ICA with formation of an arteriovenous fistula occurred, without clinical sequelae, which spontaneously resolved on follow-up. All animals tolerated the procedure and completed the follow-up surveillance. MRI revealed procedural thromboembolic induced areas of restricted diffusion, and only one instance of a delayed thromboembolic lesion during surveillance. At follow-up angiography, the devices were all patent.ConclusionWe describe a new preclinical model of intracranial stenting in the MCA. Such a model may prove useful for evaluating new surface modifications.

Several studies have shown promising outcomes of the Woven EndoBridge (WEB) device for the treatment of wide-necked intracranial bifurcation aneurysms. This is a multicenter study attempts to explore the changes in trends and treatment outcomes over time for WEB embolization of intracranial aneurysms. The WorldWideWEB consortium is a retrospective multicenter collaboration of data from international centers spanning from January 2011 and June 2021, with no limitations on aneurysm location or rupture status. Both bifurcation and sidewall aneurysms were included. These patients were stratified based on treatment year into five treatment intervals: 2011-2015 (N = 66), 2016-2017 (N = 77), 2018 (N = 66), 2019 (N = 300), and 2020-2021 (N = 173). Patient characteristics and angiographic and clinical outcomes were compared between these time intervals. This study comprised 671 patients (median age 61.4 years; 71.2% female) with 682 intracranial aneurysms. Over time, we observed an increasing tendency to treat patients presenting with ruptured aneurysms and aneurysms with smaller neck, diameter, and dome widths. Furthermore, we observed a trend towards more off-label use of the WEB for sidewall aneurysms and increased adoption of transradial access for WEB deployment. Moreover, the proportion of patients with adequate WEB occlusion immediately and at last follow-up was significantly higher in more recent year cohorts, as well as lower rates of compaction and retreatment. Mortality and complications did not differ over time. This learning curve study suggests improved experience using the WEB for the treatment of intracranial aneurysms and has yielded higher rates of adequate occlusion over time.

Optical coherence tomography (OCT) technology is a well-established diagnostic tool in multiple fields of medicine. Intravascular OCT has been used for more than a decade for the clinical imaging of coronary arteries, however, its use for the imaging of the human cerebrovasculature has been delayed by the challenges posed by the elevated vascular tortuosity. A novel high-frequency OCT (HF-OCT) probe designed for neurovascular use was evaluated in tortuous, ex vivo, human intracranial anatomy and, using an in vivo canine model, for the dynamic imaging of intracranial arteries and the subarachnoid trabecula (SAT). Using four cadavers, we investigated HF-OCT probe navigation and imaging performances in human anterior arterial circulation (from the M4 segment to internal carotid artery), in the posterior arterial circulation (from the P4 segment to vertebrobasilar junction) and in a broad range of venous sinuses. HF-OCT was able to gain distal access through elevated tortuosity and generate high-quality imaging data depicting vessel morphology, the vessel wall pathology (e.g., atherosclerotic disease and dissecting lesions), and the subarachnoid trabecula (SAT). Using an in vivo canine model, the HF-OCT probe was used to record stationary dynamic data in multiple intracranial vascular locations. Data showed the motion of the arteries and the SAT, including collisions between vessels, membranes, and the interaction between the SAT and the blood vessels. HF-OCT data allowed for the quantification of the dynamics of the vessels and the SAT, including vessel lateral motion with respect to the parenchyma, and collisions between large and small arteries. Results showed that the HF-OCT probe can overcome delivery obstacles in tortuous cerebrovascular anatomy and provide high-quality and high-resolution imaging at multiple distal locations, including M4 and P4 segments of the anterior and posterior circulations. HF-OCT has the potential to facilitate a better understanding of fine anatomical details of the cerebrovascular and perivascular environment, neurovascular disease, and collect real time information about the dynamics of the subarachnoid space and arteries and become a valuable diagnostic tool.

BackgroundSeveral animal studies have demonstrated that mechanical thrombectomy (MT) for acute ischemic stroke (AIS) may cause vessel wall injury (VWI). However, the histological changes in human cerebral arteries following MT are difficult to determine.ObjectiveTo investigate the occurrence of VWI during MT by histological and immunohistochemical evaluation of AIS clots.MethodsAs part of the multicenter STRIP registry, 277 clots from 237 patients were analyzed using Martius Scarlett Blue stain and immunohistochemistry for CD34 (endothelial cells) and smooth muscle actin (smooth muscle cells).ResultsMT devices used were aspiration catheters (100 cases), stentriever (101 cases), and both (36 cases). VWI was found in 33/277 clots (12%). There was no significant correlation between VWI and MT device. The degree of damage varied from grade I (mild intimal damage, 24 clots), to grade II (relevant intimal and subintimal damage, 3 clots), and III (severe injury, 6 clots). VWI clots contained significantly more erythrocytes (p=0.006*) and less platelets/other (p=0.005*) than non-VWI clots suggesting soft thrombus material.Thrombolysis correlated with a lower rate of VWI (p=0.04*). VWI cases showed a significantly higher number of passes (2 [1–4] vs 1 [1–3], p=0.028*) and poorer recanalization outcome (p=0.01*) than cases without VWI.ConclusionsHistological markers of VWI were present in 12% of AIS thrombi, suggesting that VWI might be related to MT. VWI was associated with soft thrombus consistency, higher number of passes and poorer revascularization outcome. There was no significant correlation between VWI and MT device.

Background and Purpose: The Tigertriever is a novel, radially adjustable, fully visible, stentriever that permits the operator to align radial expansion with target vessel diameters. This multicenter trial compared the Tigertriever’s effectiveness and safety compared with established stent retrievers. Methods: Single arm, prospective, multicenter trial comparing the Tigertriever to efficacy and safety performance goals derived from outcomes in 6 recent pivotal studies evaluating the Solitaire and Trevo stent-retriever devices with a lead-in and a main-study phase. Patients were enrolled if they had acute ischemic stroke with National Institutes of Health Stroke Scale score ≥8 due to large vessel occlusion within 8 hours of onset. The primary efficacy end point was successful reperfusion, defined as core laboratory-adjudicated modified Thrombolysis in Cerebral Ischemia score 2b-3 within 3 passes of the Tigertriever. The primary safety end point was a composite of 90-day all-cause mortality and symptomatic intracranial hemorrhage. Secondary efficacy end points included 3-month good clinical outcome (modified Rankin Scale score 0–2) and first-pass successful reperfusion. Results: Between May 2018 and March 2020, 160 patients (43 lead-in, 117 main phase) at 17 centers were enrolled and treated with the Tigertriever. The primary efficacy end point was achieved in 84.6% in the main-study phase group compared with the 63.4% performance goal and the 73.4% historical rate (noninferiority P P P =0.004; superiority P =0.57). Good clinical outcome was achieved in 58% at 90 days. Conclusions: The Tigertriever device was shown to be highly effective and safe compared with Trevo and Solitaire devices to remove thrombus in patients with large-vessel occlusive stroke eligible for mechanical thrombectomy. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03474549.

BackgroundHigh-frequency optical coherence tomography (HF-OCT) is an intravascular imaging method that allows for volumetric imaging of flow diverters in vivo.ObjectiveTo examine the hypothesis that a threshold for both volume and area of communicating malapposition can be predictive of early aneurysm occlusion.MethodsFifty-two rabbits underwent elastase aneurysm formation, followed by treatment with a flow diverter. At the time of implant, HF-OCT was acquired to study the rate and degree of communicating malapposition. Treated aneurysms were allowed to heal for either 90 or 180 days and euthanized following catheter angiography. Healing was dichotomized into aneurysm remnant or neck remnant/complete occlusion. Communicating malapposition was measured by HF-OCT using a semi-automatic algorithm able to detect any points where the flow diverter was more than 50 µm from the vessel wall. This was then summed across image slices to either a volume or area. Finally, a subsampled population was used to train a statistical classifier for the larger dataset.ResultsNo difference in occlusion rate was found between device type or follow-up time (p=0.28 and p=0.67, respectively). Both volume and area of malapposition were significantly lower in aneurysms with a good outcome (p3 or a normalized area less than 0.69 as quantified by HF-OCT was predictive of occlusion (pConclusionsHF-OCT allows for measurements of both volume and area of malapposition and, from these measurements, an accurate prediction for early aneurysm occlusion can be made.

BackgroundThe mechanisms and outcomes in coronavirus disease (COVID-19)-associated stroke are unique from those of non-COVID-19 stroke.ObjectiveTo describe the efficacy and outcomes of acute revascularization of large vessel occlusion (LVO) in the setting of COVID-19 in an international cohort.MethodsWe conducted an international multicenter retrospective study of consecutively admitted patients with COVID-19 with concomitant acute LVO across 50 comprehensive stroke centers. Our control group constituted historical controls of patients presenting with LVO and receiving a mechanical thrombectomy between January 2018 and December 2020.ResultsThe total cohort was 575 patients with acute LVO; 194 patients had COVID-19 while 381 patients did not. Patients in the COVID-19 group were younger (62.5 vs 71.2; P < .001) and lacked vascular risk factors (49, 25.3% vs 54, 14.2%; P = .001). Modified thrombolysis in cerebral infarction 3 revascularization was less common in the COVID-19 group (74, 39.2% vs 252, 67.2%; P < .001). Poor functional outcome at discharge (defined as modified Ranklin Scale 3-6) was more common in the COVID-19 group (150, 79.8% vs 132, 66.7%; P = .004). COVID-19 was independently associated with a lower likelihood of achieving modified thrombolysis in cerebral infarction 3 (odds ratio [OR]: 0.4, 95% CI: 0.2-0.7; P < .001) and unfavorable outcomes (OR: 2.5, 95% CI: 1.4-4.5; P = .002).ConclusionCOVID-19 was an independent predictor of incomplete revascularization and poor outcomes in patients with stroke due to LVO. Patients with COVID-19 with LVO were younger, had fewer cerebrovascular risk factors, and suffered from higher morbidity/mortality rates.

Carotid stenosis due to severely calcified plaque can pose a significant therapeutic challenge. Extremely calcified scars/stenosis plaques can be challenging from an endovascular treatment perspective as severely calcified lesions are prone to technical failure, stent re-coil and restenosis. Intravascular lithotripsy, approved for treatment of severely calcified coronary lesions, can be used for breaking up the calcium build up in the intimal and medial layers of the vessel wall prior to stenting. This was designated as a breakthrough device innovation by the Food and Drug Administration. This new technique addresses the challenge of the disease without compromising patient safety during the procedure. We here report procedural set-up, execution and early patient follow up from our first use of this emerging technology in a neurointerventional practice setting.

Background and aim Mechanical thrombectomy (MT) for large vessel occlusion often requires multiple passes to retrieve the entire thrombus load. In this multi-institutional study we sought to examine the composition of thrombus fragments retrieved with each pass during MT. Methods Patients who required multiple passes during thrombectomy were included. Histopathological evaluation of thrombus fragments retrieved from each pass was performed using Martius Scarlet Blue staining and the composition of each thrombus component including RBC, fibrin and platelet was determined using image analysis software. Results 154 patients underwent MT and 868 passes was performed which resulted in 263 thrombus fragments retrieval. The analysis of thrombus components per pass showed higher RBC, lower fibrin and platelet composition in the pass 1 and 2 when compared to pass 3 and passes 4 or more combined (P values 0.05). Similarly, when each composition of thrombus fragments retrieved in pass 3 and passes 4 or more combined were compared with each other, no significant difference was noted (P values >0.05). Conclusion Our findings confirm that thrombus fragments retrieved with each pass differed significantly in histological content. Fragments in the first passes were associated with lower fibrin and platelet composition compared to fragments retrieved in passes three and four or higher. Also, thrombus fragments retrieved after failed pass were associated with higher fibrin and platelet components.

BackgroundWe retrospectively evaluated the composition of retrieved clots from ischemic stroke patients to study the association between histological composition and stroke etiologyMethodsConsecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using martius scarlet blue (MSB) staining, and quantification for red blood cells (RBCs), white blood cells (WBCs), fibrin and platelets was performed using Orbit Image Software. A Wilcoxon test was used for continuous variables and χ2test for categorical variables.Results1350 patients were included in this study. The overall rate of Thrombolysis In Cerebral Infarction (TICI) 2c/3 was 68%. 501 patients received tissue plasminogen activator (tPA) (37%). 267 patients (20%) had a large artery atherosclerosis (LAA) source, 662 (49%) a cardioembolic (CE) source, 301 (22%) were cryptogenic, and the remainder had other identifiable sources including hypercoagulable state or dissection. LAA thrombi had a higher mean RBC density (46±23% vs 42±22%, p=0.01) and a lower platelet density (24±18% vs 27±18%, p=0.03) than CE thrombi. Clots from dissection patients had the highest mean RBC density (50±24%) while clots from patients with a hypercoagulable state had the lowest mean RBC density (26±21%).ConclusionsOur study found statistically significant but clinically insignificant differences between clots of CE and LAA etiologies. Future studies should emphasize molecular, proteomic and immunohistochemical characteristics to determine links between clot composition and etiology.

BackgroundStent-assisted coiling of wide-necked intracranial aneurysms (IAs) using the Neuroform Atlas Stent System (Atlas) has shown promising results.ObjectiveTo present the primary efficacy and safety results of the ATLAS Investigational Device Exemption (IDE) trial in a cohort of patients with posterior circulation IAs.MethodsThe ATLAS trial is a prospective, multicenter, single-arm, open-label study of unruptured, wide-necked, IAs treated with the Atlas stent and adjunctive coiling. This study reports the results of patients with posterior circulation IAs. The primary efficacy endpoint was complete aneurysm occlusion (Raymond-Roy (RR) class I) on 12-month angiography, in the absence of re-treatment or parent artery stenosis >50%. The primary safety endpoint was any major ipsilateral stroke or neurological death within 12 months. Adjudication of the primary endpoints was performed by an imaging core laboratory and a Clinical Events Committee.ResultsThe ATLAS trial enrolled and treated 116 patients at 25 medical centers with unruptured, wide-necked, posterior circulation IAs (mean age 60.2±10.5 years, 81.0% (94/116) female). Stents were placed in all patients with 100% technical success rate. A total of 95/116 (81.9%) patients had complete angiographic follow-up at 12 months, of whom 81 (85.3%) had complete aneurysm occlusion (RR class I). The primary effectiveness outcome was achieved in 76.7% (95% CI 67.0% to 86.5%) of patients. Overall, major ipsilateral stroke and secondary persistent neurological deficit occurred in 4.3% (5/116) and 1.7% (2/116) of patients, respectively.ConclusionsIn the ATLAS IDE posterior circulation cohort, the Neuroform Atlas Stent System with adjunctive coiling demonstrated high rates of technical and safety performance.Trial registration numberhttps://clinicaltrials.gov/ct2/show/NCT02340585.

BackgroundCatheter retention and difficulty in retrieval have been observed during embolization of brain arteriovenous malformations (bAVMs) with the Onyx liquid embolic system (Onyx). The Apollo Onyx delivery microcatheter (Apollo) is a single lumen catheter designed for controlled delivery of Onyx into the neurovasculature, with a detachable distal tip to aid catheter retrieval. This study evaluates the safety of the Apollo for delivery of Onyx during embolization of bAVMs.MethodsThis was a prospective, non-randomized, single-arm, multicenter, post-market study of patients with a bAVM who underwent Onyx embolization with the Apollo between May 2015 and February 2018. The primary endpoint was any catheter-related adverse event (AE) at 30 days, such as unintentional tip detachment or malfunction with clinical sequelae, or retained catheter. Procedure-related AEs (untoward medical occurrence, disease, injury, or clinical signs) and serious AEs (life threatening illness or injury, permanent physiological impairment, hospitalization, or requiring intervention) were also recorded.ResultsA total of 112 patients were enrolled (mean age 44.1±17.6 years, 56.3% men), and 201 Apollo devices were used in 142 embolization procedures. The mean Spetzler–Martin grade was 2.38. The primary endpoint was not observed (0/112, 0%). The catheter tip detached during 83 (58.5%) procedures, of which 2 (2.4%) were unintentional and did not result in clinical sequelae. At 30 days, procedure related AEs occurred in 26 (23.2%) patients, and procedure-related serious AEs in 12 (10.7%). At 12 months, there were 3 (2.7%) mortalities, including 2 (1.8%) neurological deaths, none of which were device-related.ConclusionThis study demonstrates the safety of Apollo for Onyx embolization of bAVMs.Clinical trial registrationCNCT02378883.

Background Neurointerventionalists use in-vitro vascular models to train for worst-case scenarios and test new devices in a simulated use environment to predict clinical performance. According to the Food and Drug Administration (FDA), any neurovascular navigation device should be able to successfully navigate two 360-degree turns and two 180-degree turns at the distal portion of the anatomical model. Here, we present a device benchmarking vascular model that complies with FDA recommendations. Methods Our vascular model was assembled from quantitative characterization of 49 patients who underwent CT angiography either for acute ischemic stroke caused by large vessel occlusion or for aneurysm treatment. Following complete characterization of these data, the vascular segments were 3D reconstructed from CT angiograms of 6 selected patients that presented with challenging anatomy. The curvature and total rotational angle were calculated for each segment and the anatomical parts that complied with FDA recommendations were fused together into a single in-vitro model. Results The model was constructed containing two common carotid branches arising from a type two aortic arch and the dimensions of the overall model exceeded the recommendations of the FDA. Two experienced neurointerventionalists tested the model for navigation difficulty using several devices on an in-vitro perfusion system and concluded that the model provided a realistic, challenging scenario. Conclusions This model provides a first prototype designed according to FDA recommendations of cumulative angle while also integrating an aggregation of actual patient-specific anatomy. The availability of this clinically relevant benchmark model presents a potential standardized approach for neurovascular device testing.

BACKGROUND AND PURPOSE: Transradial access for neurointerventional procedures has been proved a safer and more comfortable alternative to femoral artery access. We present our experience with transradial (distal radial/anatomic snuffbox and radial artery) access for treatment of intracranial aneurysms using all 3 FDA-approved flow diverters. MATERIALS AND METHODS: This was a high-volume, dual-center, retrospective analysis of each institution’s data base between June 2018 and June 2020 and a collection of all patients treated with flow diversion via transradial access. Patient demographic information and procedural and radiographic data were obtained. RESULTS: Seventy-four patients were identified (64 female patients) with a mean age of 57.5 years with a total of 86 aneurysms. Most aneurysms were located in the anterior circulation (93%) and within the intracranial ICA (67.4%). The mean aneurysm size was 5.5 mm. Flow diverters placed included the Pipeline Embolization Device (Flex) (PED, n = 65), the Surpass Streamline Flow Diverter (n = 8), and the Flow-Redirection Endoluminal Device (FRED, n = 1). Transradial access was successful in all cases, but femoral crossover was required in 3 cases (4.1%) due to tortuous anatomy and inadequate support of the catheters in 2 cases and an inability to navigate to the target vessel in a patient with an aberrant right subclavian artery. All 71 other interventions were successfully performed via the transradial approach (95.9%). No access site complications were encountered. Asymptomatic radial artery occlusion was encountered in 1 case (3.7%). CONCLUSIONS: Flow diverters can be successfully placed via the transradial approach with high technical success, low access site complications, and a low femoral crossover rate.

Background Intracranial dural arteriovenous fistulae (dAVFs) with cortical venous drainage (CVD) require treatment because of their aggressive clinical presentation and natural history. Although endovascular treatment is effective for the majority of these lesions in the current endovascular era, surgical management has been required if the lesions are not amenable to or fail endovascular treatments. Objective To demonstrate the angioarchitecture that may necessitate surgical intervention. Methods A retrospective review of the patients with intracranial dAVFs with CVD treated at 2 academic institutions between January 1, 2009, and July 31, 2019 was performed. Patients who required surgical intervention were selected in this study, and angiographic findings were analyzed. Results A total of 81 dAVFs in 80 patients were treated during the study period. Endovascular treatments were attempted for 72 (88.9%) dAVFs, resulting in complete obliteration in 55 (76.4%). Surgical interventions were performed in 18 (22.2%) dAVFs, resulting in complete obliteration in all lesions. Overall, complete obliteration was achieved in 74 (93.7%) of 79 dAVFs with follow-up. In the surgically treated dAVFs, curative transarterial embolization was deterred by the angioarchitecture, which included dominant feeding vessels from the ophthalmic artery, meningohypophyseal trunk, posterior meningeal artery, pial artery, or ascending pharyngeal artery. Drainage through tortuous cortical vein, deep venous system, or isolated sinus made transvenous approach challenging. Conclusion Despite continued improvement in endovascular technology, surgical approaches to dAVFs are still of great value as initial and salvage treatment of dAVFs with angioarchitecture hampering endovascular treatment.