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Background and Purpose: The susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) is related to thrombus location, composition, and size in acute stroke. No previous study has determined its inter-MRI scanner variability. We aimed to compare the diagnostic accuracy in-vitro of four different MRI scanners for the characterization of histologic thrombus composition.Methods: Thirty-five manufactured thrombi analogs of different composition that were histologically categorized as fibrin-dominant, mixed, or red blood cell (RBC)-dominant were scanned on four different MRI units with T2* sequence. Nine radiologists, blinded to thrombus composition and MRI scanner model, classified twice, in a 2-week interval, the SVS of each thrombus as absent, questionable, or present. We calculated the weighted kappa with 95% confidence interval (CI), sensitivity, specificity and accuracy of the SVS on each MRI scanner to detect RBC-dominant thrombi.Results: The SVS was present in 42%, absent in 33%, and questionable in 25% of thrombi. The interscanner agreement was moderate to good, ranging from .45 (CI: .37-.52) to .67 (CI: .61-.74). The correlation between the SVS and the thrombus composition was moderate (κ: .50 [CI: .44-.55]) to good κ: .76 ([CI: .72-.80]). Sensitivity, specificity, and accuracy to identify RBC-dominant clots were significantly different between MRI scanners (P < .001).Conclusion: The diagnostic accuracy of SVS to determine thrombus composition varies significantly among MRI scanners. Normalization of T2*sequences between scanners may be needed to better predict thrombus composition in multicenter studies. [ABSTRACT FROM AUTHOR]

Objective To report our experience with the Embolus Retriever with Interlinked Cage (ERIC) stentriever for use in mechanical endovascular thrombectomy (MET). Methods Thirty-four consecutive patients with acute stroke (21 men and 13 women; median age 66 years) determined appropriate for MET were treated with ERIC and prospectively included over a 6-month period at three different centers. The ERIC device differs from typical stentrievers in that it is designed with a series of interlinked adjustable nitinol cages that allow for fast thrombus capture, integration, and withdrawal. The evaluated endpoints were successful revascularization (Thrombolysis in Cerebral Infarction (TICI) 2b-3) and good clinical outcomes at 3 months (modified Rankin Scale (mRS) 0-2). Results Locations of the occlusions included the middle cerebral artery (13 patients), terminal carotid artery (11 patients), basilar artery (1 patient), and tandem occlusions (9 patients). IV thrombolysis was performed in 20/34 (58.8%) patients. Median times from symptom onset to recanalization and from puncture to recanalization were 325.5 min (180-557) and 78.5 min (14-183), respectively. Used as the first-line device, ERIC achieved a successful recanalization in 20/24 (83.3%) patients. Successful recanalization was associated with lower National Institutes of Health Stroke Scale scores at 24 h (8±6.5 vs 21.5±2.1; p=0.008) and lower mRS at 3 months (2.7±2.1 vs 5.3±1.1; p=0.04). Three procedural complications and four asymptomatic hemorrhages were recorded. Good clinical outcomes at 3 months were seen in 15/31 (48.4%) patients. Conclusions The ERIC device is an innovative stentriever allowing fast, effective, and safe MET. [ABSTRACT FROM AUTHOR]

Purpose: Stress cardiomyopathy is a common life-threatening complication after aneurysmal subarachnoid hemorrhage (SAH). We hypothesized that left ventricular (LV) longitudinal strain alterations assessed with speckle tracking could identify early systolic function impairment.Methods: This was an observational single-center prospective pilot controlled study conducted in a neuro-intensive care unit. Forty-six patients with severe SAH with a World Federation of Neurological Surgeons grade (WFNS) ≥ III were included. Transthoracic echocardiography (TTE) was performed on day 1, day 3, and day 7 after the patient's admission. A cardiologist blinded to the patient's management analyzed the LV global longitudinal strain (GLS). The control group comprised normal subjects matched according to gender and age.Results: On day 1 median (25th-75th percentile) GLS was clearly impaired in SAH patients compared to controls [-16.7 (-18.7/-13.7) % versus -20 (-22/-19) %, p < 0.0001], whereas LVEF was preserved [65 (59-70) %]. GLS was severely impaired in patients with a WFNS score of V versus III-IV [-15.6 (-16.9/-12.3) % versus -17.8 (-20.6/-15.8) %, p = 0.008]. Seventeen (37 %) patients had a severe GLS alteration (>- 16 %). In these patients, GLS improved from day 1 [-12.4 (-14.8/-10.9) %] to last evaluation [-16.2 (-19/-14.6) %, p = 0.0007] in agreement with the natural evolution of stress cardiomyopathy.Conclusions: On the basis of LV GLS assessment, we demonstrated for the first time that myocardial alteration compatible with a stress cardiomyopathy is detectable in up to 37 % of patients with severe SAH while LVEF is preserved. GLS could be used for sensitive detection of stress cardiomyopathy. This is critical because cardiac impairment remains a major cause of morbidity and mortality after SAH. [ABSTRACT FROM AUTHOR]

Background and Purpose: The "white" compared to "Red-Black" visual aspect of the thrombus at withdrawal with mechanical thrombectomy (MT) for acute ischemic stroke (AIS) was related to atypical etiologies like infective endocarditis. The susceptibility vessel sign (SVS) and the two-layered SVS (TL-SVS) could help predict outcome and cardio-embolic etiology of AIS. We aim to evaluate the diagnostic performance of the SVS and TLSVS to predict the visual aspect of the thrombus.Materials and Methods: We included patients treated by MT and screened with MRI for the SVS and the TL-SVS for whom thrombus photograph was available. Photographs underwent a double-blind evaluation by neuroradiologists who classified the thrombus as "White" or "Red-Black". Logistic regression assessed the association of Red-Black thrombus and age, sex, baseline National Institutes of Health Stroke Scale, occlusion site, the IVr-tPA administration, SVS and TL-SVS. We calculated the diagnostic performances of the SVS to predict a Red-Black type thrombus.Results: Between May 2017 and July 2018, 139 patients were included in the study. On multivariate analysis, only SVS was an independent predictor for Red-Black thrombus (Odd ratio 8.31, 95%CI2.30 to 32, p value<0.001). Concerning SVS diagnostic performances, the specificity was 0.58 (95%CI0.28 to 0.85), the sensitivity was 0.87 (95%CI0.80 to 0.93), the negative predictive value was 0.30 (95% 0.13 to 0.53), the positive predictive value was 0.96 (95%CI0.90 to 0.99) and accuracy was 0.85 (95%CI0.78 to 0.90).Conclusion: The SVS on MRI provides a good prediction accuracy to anticipate the macroscopic visual aspect of the thrombus after MT for AIS. [ABSTRACT FROM AUTHOR]

Intracranial aneurysms (IAs) are usually asymptomatic with a low risk of rupture, but consequences of aneurysmal subarachnoid hemorrhage (aSAH) are severe. Identifying IAs at risk of rupture has important clinical and socio-economic consequences. The goal of this study was to assess the effect of patient and IA characteristics on the likelihood of IA being diagnosed incidentally versus ruptured. Patients were recruited at 21 international centers. Seven phenotypic patient characteristics and three IA characteristics were recorded. The analyzed cohort included 7992 patients. Multivariate analysis demonstrated that: (1) IA location is the strongest factor associated with IA rupture status at diagnosis; (2) Risk factor awareness (hypertension, smoking) increases the likelihood of being diagnosed with unruptured IA; (3) Patients with ruptured IAs in high-risk locations tend to be older, and their IAs are smaller; (4) Smokers with ruptured IAs tend to be younger, and their IAs are larger; (5) Female patients with ruptured IAs tend to be older, and their IAs are smaller; (6) IA size and age at rupture correlate. The assessment of associations regarding patient and IA characteristics with IA rupture allows us to refine IA disease models and provide data to develop risk instruments for clinicians to support personalized decision-making. [ABSTRACT FROM AUTHOR]

Background: The best treatment for acute ischemic stroke (AIS) due to isolated cervical internal carotid artery occlusion (CICAO) (i.e., without associated occlusion of the circle of Willis) is still unknown. In this study, we aimed to describe EVT safety and clinical outcome in patients with CICAO. Methods: We analyzed data of all consecutive patients, included in the Endovascular Treatment in Ischemic Stroke (ETIS) Registry between 2013 and 2020, who presented AIS and proven CICAO on angiogram and underwent EVT. We assessed carotid recanalization, procedural complications, National Institutes of Health Stroke Scale (NIHSS) at 24 h post-EVT, and 3-month favorable outcome (modified Rankin Scale, mRS ≤ 2 or equal to the pre-stroke value). Results: Forty-five patients were included (median age: 70 years; range: 62–82 years). The median NIHSS before EVT was 14 (9–21). Carotid stenting was performed in 23 (51%) patients. Carotid recanalization at procedure end and on control imaging was observed in 37 (82%) and 29 (70%) patients, respectively. At day 1 post-EVT, the NIHSS remained stable or decreased in 25 (60%) patients; 12 (29%) patients had early neurologic deterioration (NIHSS ≥ 4 points). The rate of procedural complications was 36%, including stent thrombosis (n = 7), intracranial embolism (n = 7), and symptomatic intracranial hemorrhage (n = 1). At 3 months, 18 (40%) patients had a favorable outcome, and 10 (22%) were dead. Conclusion: Our study suggests that EVT in AIS patients with moderate/severe initial deficit due to CICAO led to high rate of recanalization at day 1, and a 40% rate of favorable outcome at 3 months. There was a high rate of procedural complication which is of concern. Randomized controlled trials assessing the superiority of EVT in patients with CICAO and severe deficits are needed. [ABSTRACT FROM AUTHOR]

Background: Whether thrombectomy alone is equally as effective as intravenous alteplase plus thrombectomy remains controversial. We aimed to determine whether thrombectomy alone would be non-inferior to intravenous alteplase plus thrombectomy in patients presenting with acute ischaemic stroke.Methods: In this multicentre, randomised, open-label, blinded-outcome trial in Europe and Canada, we recruited patients with stroke due to large vessel occlusion confirmed with CT or magnetic resonance angiography admitted to endovascular centres. Patients were randomly assigned (1:1) via a centralised web server using a deterministic minimisation method to receive stent-retriever thrombectomy alone or intravenous alteplase plus stent-retriever thrombectomy. In both groups, thrombectomy was initiated as fast as possible with any commercially available Solitaire stent-retriever revascularisation device (Medtronic, Irvine, CA, USA). In the combined treatment group, intravenous alteplase (0·9 mg/kg bodyweight, maximum dose 90 mg per patient) was administered as early as possible after randomisation for 60 min with 10% of the calculated dose given as an initial bolus. Personnel assessing the primary outcome were masked to group allocation; patients and treating physicians were not. The primary binary outcome was a score of 2 or less on the modified Rankin scale at 90 days. We assessed the non-inferiority of thrombectomy alone versus intravenous alteplase plus thrombectomy in all randomly assigned and consenting patients using the one-sided lower 95% confidence limit of the Mantel-Haenszel risk difference, with a prespecified non-inferiority margin of 12%. The main safety endpoint was symptomatic intracranial haemorrhage assessed in all randomly assigned and consenting participants. This trial is registered with ClinicalTrials.gov, NCT03192332, and is closed to new participants.Findings: Between Nov 29, 2017, and May 7, 2021, 5215 patients were screened and 423 were randomly assigned, of whom 408 (201 thrombectomy alone, 207 intravenous alteplase plus thrombectomy) were included in the primary efficacy analysis. A modified Rankin scale score of 0-2 at 90 days was reached by 114 (57%) of 201 patients assigned to thrombectomy alone and 135 (65%) of 207 patients assigned to intravenous alteplase plus thrombectomy (adjusted risk difference -7·3%, 95% CI -16·6 to 2·1, lower limit of one-sided 95% CI -15·1%, crossing the non-inferiority margin of -12%). Symptomatic intracranial haemorrhage occurred in five (2%) of 201 patients undergoing thrombectomy alone and seven (3%) of 202 patients receiving intravenous alteplase plus thrombectomy (risk difference -1·0%, 95% CI -4·8 to 2·7). Successful reperfusion was less common in patients assigned to thrombectomy alone (182 [91%] of 201 vs 199 [96%] of 207, risk difference -5·1%, 95% CI -10·2 to 0·0, p=0·047).Interpretation: Thrombectomy alone was not shown to be non-inferior to intravenous alteplase plus thrombectomy and resulted in decreased reperfusion rates. These results do not support omitting intravenous alteplase before thrombectomy in eligible patients.Funding: Medtronic and University Hospital Bern. [ABSTRACT FROM AUTHOR]

Background: Intravenous (IV) milrinone, in combination with induced hypertension, has been proposed as a treatment option for cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). However, data on its safety and efficacy are scarce. Methods: This was a controlled observational study conducted in an academic hospital with prospectively and retrospectively collected data. Consecutive patients with cerebral vasospasm following aSAH and treated with both IV milrinone (0.5 µg/kg/min−1, as part of a strict protocol) and induced hypertension were compared with a historical control group receiving hypertension alone. Multivariable analyses aimed at minimizing potential biases. We assessed (1) 6-month functional disability (defined as a score between 2 and 6 on the modified Rankin Scale) and vasospasm-related brain infarction, (2) the rate of first-line or rescue endovascular angioplasty for vasospasm, and (3) immediate tolerance to IV milrinone. Results: Ninety-four patients were included (41 and 53 in the IV milrinone and the control group, respectively). IV milrinone infusion was independently associated with a lower likelihood of 6-month functional disability (adjusted odds ratio [aOR] = 0.28, 95% confidence interval [CI] = 0.10–0.77]) and vasospasm-related brain infarction (aOR = 0.19, 95% CI 0.04–0.94). Endovascular angioplasty was less frequent in the IV milrinone group (6 [15%] vs. 28 [53%] patients, p = 0.0001, aOR = 0.12, 95% CI 0.04–0.38). IV milrinone (median duration of infusion, 5 [2–8] days) was prematurely discontinued owing to poor tolerance in 12 patients, mostly (n = 10) for "non/hardly-attained induced hypertension" (mean arterial blood pressure < 100 mmHg despite 1.5 µg/kg/min−1 of norepinephrine). However, this event was similarly observed in IV milrinone and control patients (n = 10 [24%] vs. n = 11 [21%], respectively, p = 0.68). IV milrinone was associated with a higher incidence of polyuria (IV milrinone patients had creatinine clearance of 191 [153–238] ml/min−1) and hyponatremia or hypokalemia, whereas arrhythmia, myocardial ischemia, and thrombocytopenia were infrequent. Conclusions: Despite its premature discontinuation in 29% of patients as a result of its poor tolerance, IV milrinone was associated with a lower rate of endovascular angioplasty and a positive impact on long-term neurological and radiological outcomes. These preliminary findings encourage the conduction of confirmatory randomized trials. [ABSTRACT FROM AUTHOR]

In the absence of randomized evidence, the optimal management of patients with unruptured intracranial aneurysms (UIA) remains uncertain. Comprehensive Aneurysm Management (CAM) is an all-inclusive care trial combined with a registry. Any patient with a UIA (no history of intracranial hemorrhage within the previous 30 days) can be recruited, and treatment allocation will follow an algorithm combining clinical judgment and randomization. Patients eligible for at least 2 management options will be randomly allocated 1:1 to conservative or curative treatment. Minimization will be used to balance risk factors, using aneurysm size (≥7 mm), location (anterior or posterior circulation), and age <60 years. The CAM primary outcome is survival without neurologic dependency (modified Rankin Scale [mRS] score <3) at 10 years. Secondary outcome measures include the incidence of subarachnoid hemorrhage during follow-up and related morbidity and mortality; morbidity and mortality related to endovascular treatment or surgical treatment of the UIA at 1 year; overall morbidity and mortality at 1, 5, and 10 years; when relevant, duration of hospitalization; and, when relevant, discharge to a location other than home. The primary hypothesis for patients randomly allocated to at least 2 options, 1 of which is conservative management, is that active UIA treatment will reduce the 10-year combined neurologic morbidity and mortality (mRS score >2) from 24% to 16%. At least 961 patients recruited from at least 20 centers over 4 years will be needed for the randomized portion of the study. Patients with unruptured intracranial aneurysms can be comprehensively managed within the context of an all-inclusive care trial. [ABSTRACT FROM AUTHOR]

The Alberta Stroke Program Early CT scan Score (ASPECTS) is a reliable imaging biomarker of infarct extent on admission but the value of 24-hour ASPECTS evolution in day-to-day practice is not well studied, especially after successful reperfusion. We aimed to assess the association between ASPECTS evolution after successful reperfusion with functional and safety outcomes, as well as to identify the predictors of ASPECTS evolution.We used data from an ongoing prospective multicenter registry. Stroke patients with anterior circulation large vessel occlusion treated with endovascular therapy (EVT) and achieved successful reperfusion (modified thrombolysis in cerebral ischemia (mTICI) 2b-3) were included. ASPECTS evolution was defined as one or more point decrease in ASPECTS at 24 hours.A total of 2366 patients were enrolled. In a fully adjusted model, ASPECTS evolution was associated with lower odds of favorable outcome (modified Rankin Scale (mRS) score 0-2) at 90 days (adjusted odds ratio (aOR) = 0.46; 95% confidence interval (CI) = 0.37–0.57). In addition, ASPECTS evolution was a predictor of excellent outcome (90-day mRS 0-1) (aOR = 0.52; 95% CI = 0.49–0.57), early neurological improvement (aOR = 0.42; 95% CI = 0.35–0.51), and parenchymal hemorrhage (aOR = 2.64; 95% CI, 2.03–3.44). Stroke severity, admission ASPECTS, total number of passes, complete reperfusion (mTICI 3 vs. mTICI 2b-2c) and good collaterals emerged as predictors of ASPECTS evolution.ASPECTS evolution is a strong predictor of functional and safety outcomes after successful endovascular therapy. Higher number of EVT attempts and incomplete reperfusion are associated with ASPECTS evolution at day 1. [ABSTRACT FROM AUTHOR]

Background: Aneurysm location is a key element in predicting the rupture risk of an intracranial aneurysm. A common impression suggests that pure ophthalmic aneurysms are under-represented in ruptured intracranial aneurysms (RIAs). The purpose of this study was to specifically evaluate the risk of rupture of ophthalmic aneurysms compared with other aneurysm locations., Methods: This multicenter study compared the frequency of ophthalmic aneurysms in a prospective cohort of RIAs admitted to 13 neuroradiology centers between January 2021 and March 2021, with a retrospective cohort of patients with unruptured intracranial aneurysms (UIAs) who underwent cerebral angiography at the same neuroradiology centers during the same time period., Results: 604 intracranial aneurysms were included in this study (355 UIAs and 249 RIAs; mean age 57 years (IQR 49-65); women 309/486, 64%). Mean aneurysm size was 6.0 mm (5.3 mm for UIAs, 7.0 mm for RIAs; P<0.0001). Aneurysm shape was irregular for 37% UIAs and 73% RIAs (P<0.0001). Ophthalmic aneurysms frequency was 14.9% of UIAs (second most common aneurysm location) and 1.2% of RIAs (second least common aneurysm location; OR 0.07 (95% CI 0.02 to 0.23), P<0.0001)., Conclusions: Ophthalmic aneurysms seem to have a low risk of rupture compared with other intracranial aneurysm locations. This calls for a re-evaluation of the benefit-risk balance when considering preventive treatment for ophthalmic aneurysms., Competing Interests: Competing interests: FC is a consultant for Medtronic, Balt Extrusion, Penumbra, Microvention, and Stryker; board member of Artedrone, and has stock options with Intradys and Collavidence. GM is a consultant for Stryker Neurovascular, Balt, Microvention Europe, and Sim and Cure, and has done paid lectures for Medtronic, Phenox, Johnson & Johnson, and Bracco. KJ is a consultant for Balt. AR is a consultant for Balt, Medtronic, Microvention, and Stryker. N-AS is a consultant for Balt, Medtronic Extrusion, and Microvention., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Purpose: Vasospasm is a common iatrogenic event during mechanical thrombectomy (MT). In such circumstances, intra-arterial nimodipine administration is occasionally considered. However, its use in the treatment of iatrogenic vasospasm during MT has been poorly studied. We investigated the impact of iatrogenic vasospasm treated with intra-arterial nimodipine on outcomes after MT for large vessel occlusion stroke., Methods: We conducted a retrospective analysis of the multicenter observational registry Endovascular Treatment in Ischemic Stroke (ETIS). Consecutive patients treated with MT between January 2015 and December 2022 were included. Patients treated with medical treatment alone, without MT, were excluded. We also excluded patients who received another in situ vasodilator molecule during the procedure. Outcomes were compared according to the occurrence of cervical and/or intracranial arterial vasospasm requiring intraoperative use of in situ nimodipine based on operator's decision, using a propensity score approach. The primary outcome was a modified Rankin Scale (mRS) score of 0-2 at 90 days. Secondary outcomes included excellent outcome (mRS score 0-1), final recanalization, mortality, intracranial hemorrhage and procedural complications. Secondary analyses were performed according to the vasospasm location (intracranial or cervical)., Results: Among 13,678 patients in the registry during the study period, 434 received intra-arterial nimodipine for the treatment of MT-related vasospasm. In the main analysis, comparable odds of favorable outcome were observed, whereas excellent outcome was significantly less frequent in the group with vasospasm requiring nimodipine (adjusted odds ratio [aOR] 0.78, 95% confidence interval [CI] 0.63-0.97). Perfect recanalization, defined as a final modified Thrombolysis In Cerebral Infarction score of 3 (aOR 0.63, 95% CI 0.42-0.93), was also rarer in the vasospasm group. Intracranial vasospasm treated with nimodipine was significantly associated with worse clinical outcome (aOR 0.64, 95% CI 0.45-0.92), in contrast to the cervical location (aOR 1.37, 95% CI 0.54-3.08)., Conclusion: Arterial vasospasm occurring during the MT procedure and requiring intra-arterial nimodipine administration was associated with worse outcomes, especially in case of intracranial vasospasm. Although this study cannot formally differentiate whether the negative consequences were due to the vasospasm itself, or nimodipine administration or both, there might be an important signal toward a substantial clinical impact of iatrogenic vasospasm during MT., (© 2024 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Objective: Identifying the optimal anesthetic technique for mechanical thrombectomy (MT) remains an unresolved issue. Prior research has not considered the influence of occlusion site when comparing general anesthesia (GA) with non-GA. This study evaluates the differential impacts of the anesthetic technique (GA vs non-GA) on outcomes according to the location of occlusion., Methods: This is a retrospective analysis of the ETIS (Endovascular Treatment in Ischemic Stroke) registry. Patients with anterior circulation large-vessel occlusion treated with MT were included. Patients were divided into groups according to the location of occlusion. Inverse propensity score weighting analysis was used., Results: Among 2783 patients included in the propensity score analysis, 669 (24%) received GA. In the total cohort, GA was not associated with favorable outcome, excellent outcome, successful reperfusion, or complete reperfusion. GA was associated with higher odds of parenchymal hemorrhage (OR 1.42, 95% 1.05-1.92) but not symptomatic intracranial hemorrhage. GA was associated with Alberta Stroke Program Early CT Score progression (OR 1.36, 95% CI 1.11-1.68). In the internal carotid artery occlusion group, GA was associated with higher odds of mortality (OR 1.94, 95% CI 1.15-3.27). In the M1 group, GA was associated with lower odds of complications (OR 0.41, 95% CI 0.19-0.92). In the M2 group, GA was associated with successful reperfusion (OR 2.79, 95% CI 1.02-7.64). In addition, the complication rate was lower with GA (2.7% vs 7%), although the association was not significant in adjusted analysis., Conclusions: While GA and non-GA techniques did not differ significantly in functional outcomes, the influence of GA on angiographic and procedural safety outcomes was location dependent, underscoring the importance of a tailored anesthesia technique in MT procedures.

Objectives: Unruptured cerebral aneurysms (UCAs) often coexist with the ruptured one but are typically left unsecured during the weeks following aneurysmal subarachnoid hemorrhage (aSAH). We compared the rate of UCAs rupture or volume growth (≥5 mm 3 ) between patients exposed to induced arterial hypertension (iHTN) for vasospasm and those not exposed (control group)., Materials and Methods: From 2013 to 2021, we retrospectively included consecutive adult patients with aSAH who had ≥1 UCA. Custom software for digital subtraction angiography (DSA) image analysis characterized UCAs volume, going beyond merely considering UCAs long axis., Results: We analyzed 118 patients (180 UCAs): 45 in the iHTN group (64 UCAs) and 73 in the control group (116 UCAs). Systolic blood pressure in the iHTN group was significantly higher than in the control group for several days after aSAH. During the 107 day-monitoring period [interquartile range(IQR):92;128], no UCA rupture occurred in either group. UCA volume analysis was performed in 44 patients (60 UCAs): none of the UCAs in the iHTN group and 3 out of 42 (7%) in the control group had a >5 mm 3 volume growth (p=0.55). Other morphologic parameters did not exhibit any variations that might indicate an increased risk of rupture in the iHTN group compared to the control group., Conclusion: iHTN did not increase the risk of rupture or volume growth of UCAs within several weeks following aSAH. These reassuring results encourage not to refrain, because of the existence of UCAs, from iHTN as an option to prevent cerebral infarction during cerebral vasospasm., Competing Interests: Declaration of competing interest Karim Lakhal has no conflict of interest in connection with the work submitted. In addition, KL received, during the past 3 years, congress registration from Pfizer (once in 2022) and both congress registration and travel fees from Advanz Pharma/Correvio (once in 2021) and AOP Health (once in 2024). Aude Missonnier has no conflict of interest in connection with the work submitted. Vincent L'Allinec has no conflict of interest in connection with the work submitted. Pacôme Constant dit Beaufils has no conflict of interest in connection with the work submitted. Florent Autrusseau has no conflict of interest in connection with the work submitted. Anass Nouri has no conflict of interest in connection with the work submitted. Matilde Karakachoff has no conflict of interest in connection with the work submitted. Bertrand Rozec has no conflict of interest in connection with the work submitted. Romain Bourcier has no conflict of interest in connection with the work submitted., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Non-ischemic cerebral enhancing (NICE) lesions following aneurysm endovascular therapy are exceptionally rare, with unknown longitudinal evolution., Objective: To evaluate the radiological behavior of individual NICE lesions over time., Methods: Patients included in a retrospective national multicentric inception cohort were analyzed. NICE lesions were defined, using MRI, as delayed onset punctate, nodular, or annular foci enhancements with peri-lesion edema, distributed in the vascular territory of the aneurysm treatment, with no other confounding disease. Lesion burden and the longitudinal behavior of individual lesions were assessed., Results: Twenty-two patients were included, with a median initial lesion burden of 36 (IQR 17-54) on the first MRI scan. Of the 22 patients with at least one follow-up MRI scan, 16 (73%) had new lesions occurring mainly within the first 200 weeks after the date of the procedure. The median number of new lesions per MRI was 6 (IQR 2-16). Among the same 22 patients, 7 (32%) had recurrent lesions. The median persistent enhancement of a NICE lesion was 13 weeks (IQR 6-30). No factor was predictive of early regression of enhancement activity with lesion regression kinetics mainly being patient-dependent., Conclusions: The behavior of individual NICE lesions was found to be highly variable with an overall patient-dependent regression velocity., Competing Interests: Competing interests: FC reports conflict of interest with Medtronic, Guerbet, Balt Extrusion (payment for readings), Codman Neurovascular (core laboratory). N-AS is consultant for Medtronic, Balt Extrusion, Microvention; stock/stock options: Medina. The other authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. The manuscript is not supported by industry., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background and Objectives: IV tenecteplase is an alternative to alteplase before mechanical thrombectomy (MT) in patients with large-vessel occlusion (LVO) ischemic stroke. Little data are available on its use in patients with large ischemic core. We aimed to compare the efficacy and safety of both thrombolytics in this population., Methods: We conducted a retrospective analysis of patients with anterior circulation LVO strokes and diffusion-weighed imaging Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≤5 treated with tenecteplase or alteplase before MT from the TETRIS (tenecteplase) and ETIS (alteplase) French multicenter registries. Primary outcome was reduced disability at 3 months (ordinal analysis of the modified Rankin scale [mRS]). Safety outcomes were 3-month mortality, parenchymal hematoma (PH), and symptomatic intracranial hemorrhage (sICH). We used propensity score overlap weighting to reduce baseline differences between treatment groups., Results: We analyzed 647 patients (tenecteplase: n = 194; alteplase: n = 453; inclusion period 2015-2022). Median (interquartile range) age was 71 (57-81) years, with NIH Stroke Scale score 19 (16-22), DWI-ASPECTS 4 (3-5), and last seen well-to-IV thrombolysis and puncture times 165 minutes (130-226) and 260 minutes (203-349), respectively. After MT, the successful reperfusion rate was 83.1%. After propensity score overlap weighting, all baseline variables were well balanced between both treatment groups. Compared with patients treated with alteplase, patients treated with tenecteplase had better 3-month mRS (common odds ratio [OR] for reduced disability: 1.37, 1.01-1.87, p = 0.046) and lower 3-month mortality (OR 0.52, 0.33-0.81, p < 0.01). There were no significant differences between thrombolytics for PH (OR 0.84, 0.55-1.30, p = 0.44) and sICH incidence (OR 0.70, 0.42-1.18, p = 0.18)., Discussion: Our data are encouraging regarding the efficacy and reassuring regarding the safety of tenecteplase compared with that of alteplase in bridging therapy for patients with LVO strokes and a large ischemic core in routine clinical care. These results support its consideration as an alternative to alteplase in bridging therapy for patients with large ischemic cores., Trials Registration Information: NCT03776877 (ETIS registry) and NCT05534360 (TETRIS registry)., Classification of Evidence: This study provides Class III evidence that patients with anterior circulation LVO stroke and DWI-ASPECTS ≤5 treated with tenecteplase vs alteplase before MT experienced better functional outcomes and lower mortality at 3 months.

Background: Positive susceptibility vessel sign (SVS) in patients with acute ischaemic stroke has been associated with friable red blood cell-rich clots and more effective recanalisation using stent retrievers versus contact aspiration. We compared the safety and efficacy of stent retrievers plus contact aspiration (combined technique) versus contact aspiration alone as the first-line thrombectomy technique in patients with acute ischaemic anterior circulation stroke and SVS-positive occlusions., Methods: Adaptive Endovascular Strategy to the Clot MRI in Large Intracranial Vessel Occlusion (VECTOR) was a prospective, randomised, open-label study with blinded evaluation. Patients with SVS-positive anterior circulation occlusions on pretreatment MRI and arterial puncture within 24 h of symptom onset were enrolled from 22 centres in France. A centralised web-based method was used by interventional neuroradiologists for dynamic randomisation by minimisation. Patients were randomly assigned 1:1 to the combined technique or contact aspiration alone. The primary outcome was expanded Thrombolysis in Cerebral Infarction (eTICI) grade 2c or 3 reperfusion after three or fewer passes on post-treatment angiogram, adjudicated by a blinded independent central imaging core laboratory. The intention-to-treat population was used to assess the primary and secondary outcomes. This trial is registered with ClinicalTrials.gov (NCT04139486) and is complete., Findings: Between Nov 26, 2019, and Feb 14, 2022, 526 patients were enrolled, of whom 521 constituted the intention-to-treat population (combined technique, n=263; contact aspiration alone, n=258). The median age of participants was 74·9 years (IQR 64·4-83·3); 284 (55%) were female and 237 (45%) male. The primary outcome did not differ significantly between groups (152 [58%] of 263 patients for the combined technique vs 135 [52%] of 258 for contact aspiration; odds ratio [OR] 1·27; 95% CI 0·88-1·83; p=0·19). Procedure-related adverse events occurred in 32 (12%) of 263 patients in the combined technique group and 27 (11%) of 257 in the contact aspiration group (OR 1·14; 0·65-2·00; p=0·65). The most common adverse event was intracerebral haemorrhage (146 [56%] of 259 patients for the combined technique vs 123 [49%] of 251 for contact aspiration; OR 1·32; 0·91-1·90; p=0·13). All-cause mortality at 3 months occurred in 57 (23%) of 251 patients in the combined technique group and 48 (19%) of 247 in the contact aspiration group (OR 1·19; 0·76-1·86; p=0·45), none of which was treatment-related., Interpretation: The results of the VECTOR trial do not show superiority of the combined stent retriever plus contact aspiration technique over contact aspiration alone in patients with SVS-positive occlusion with respect to achieving eTICI 2c-3 within three passes. These findings support the use of either the combined technique or contact aspiration alone as the initial thrombectomy strategy in patients with acute anterior circulation stroke with SVS on pretreatment MRI., Funding: Cerenovus., Competing Interests: Declaration of interests RB reports paid lectures for Microvention, Medtronic, Penumbra, and Johnson & Johnson (Cerenovus). GM reports consulting for Balt, Microvention Europe, and Stryker Neurovascular; and paid lectures for Phenox, Medtronic, Johnson & Johnson (Cerenovus), and Bracco. KJ reports consulting for Balt. J-CG reports consulting for Balt, Stryker, Phenox, and Medtronic. FC reports consulting for Medtronic, Balt Extrusion, Penumbra, Microvention, and Stryker; being a board member of Artedrone; and having stock options with Intradys and Letsgetproof. XB reports consulting for Stryker and Microvention. SS reports consulting for Phillips Healthcare; support for attending meetings and travel from Cerenovus, Microvention, and Balt; and paid lectures for EISAI. JSR reports paid lectures for Medtronic and Johnson & Johnson (Cerenovus). All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Background: We evaluated the clinical and safety outcomes of emergent carotid artery stenting (eCAS) plus endovascular thrombectomy (EVT) among patients with anterior tandem lesion (TL) and large ischemic core (LIC)., Methods: This retrospective study included consecutive stroke patients enrolled in the Endovascular Treatment in Ischemic Stroke Registry in France between January 2015 and June 2023. We compared the outcomes of carotid stenting vs no stenting in tandem lesion with pre-treatment LIC (Alberta Stroke Program Early CT Score (ASPECTS) 3-5) and stenting in tandem lesion vs thrombectomy alone for isolated intracranial occlusions with pre-treatment LIC. Primary outcome was a score of 0 to 3 on the modified Rankin scale (mRS) at 90 days. Multivariable mixed-effects logistic regression was performed., Results: Among 218 tandem patients with LIC, 55 were treated with eCAS plus EVT. The eCAS group had higher odds of 90-day mRS 0-3 (adjusted Odds Ratio (aOR) 2.40, 95% confidence interval (CI) 1.10 to 5.21; p=0.027). There were no differences in the risk of any intracerebral hemorrhage (OR 1.41, 95% CI 0.69 to 2.86; p=0.346), parenchymal hematoma (aOR 1.216, 95% CI 0.49 to 3.02; p=0.675), symptomatic intracerebral hemorrhage (aOR 1.45, 95% CI 0.60 to 3.48; p=0.409), or 90-day mortality (aOR 0.74, 95% CI 0.33 to 1.68; p=0.472). eCAS was associated with a higher rate of carotid patency at day 1 (aOR 3.54, 95% CI 1.14 to 11.01; p=0.028). Safety outcomes were similar between EVT+eCAS group in TL-LIC and EVT alone group in isolated intracranial occlusions with LIC., Conclusion: eCAS appears to be a safe and effective strategy in patients with TL and LIC volume., Competing Interests: Competing interests: Dr. Marnat reports consulting fees from Microvention and Stryker outside the submitted work. Dr. Soize reports personal fees from Balt and Microvention outside the submitted work. Dr. Richard reports consulting fees from Stryker and Microvention outside the submitted work. Dr. Bourcier reports consulting fees from ACTICOR and payments for lectures from ACTICOR, BMS, Pfizer, and Bayer outside the submitted work. Dr. Casolla reports consulting fees from ACTICOR and payments for lectures from ACTICOR, BMS, Pfizer, and Bayer outside the submitted work. The other authors report no conflicts., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The use of thrombectomy in patients with acute stroke and a large infarct of unrestricted size has not been well studied., Methods: We assigned, in a 1:1 ratio, patients with proximal cerebral vessel occlusion in the anterior circulation and a large infarct (as defined by an Alberta Stroke Program Early Computed Tomographic Score of ≤5; values range from 0 to 10) detected on magnetic resonance imaging or computed tomography within 6.5 hours after symptom onset to undergo endovascular thrombectomy and receive medical care (thrombectomy group) or to receive medical care alone (control group). The primary outcome was the score on the modified Rankin scale at 90 days (scores range from 0 to 6, with higher scores indicating greater disability). The primary safety outcome was death from any cause at 90 days, and an ancillary safety outcome was symptomatic intracerebral hemorrhage., Results: A total of 333 patients were assigned to either the thrombectomy group (166 patients) or the control group (167 patients); 9 were excluded from the analysis because of consent withdrawal or legal reasons. The trial was stopped early because results of similar trials favored thrombectomy. Approximately 35% of the patients received thrombolysis therapy. The median modified Rankin scale score at 90 days was 4 in the thrombectomy group and 6 in the control group (generalized odds ratio, 1.63; 95% confidence interval [CI], 1.29 to 2.06; P<0.001). Death from any cause at 90 days occurred in 36.1% of the patients in the thrombectomy group and in 55.5% of those in the control group (adjusted relative risk, 0.65; 95% CI, 0.50 to 0.84), and the percentage of patients with symptomatic intracerebral hemorrhage was 9.6% and 5.7%, respectively (adjusted relative risk, 1.73; 95% CI, 0.78 to 4.68). Eleven procedure-related complications occurred in the thrombectomy group., Conclusions: In patients with acute stroke and a large infarct of unrestricted size, thrombectomy plus medical care resulted in better functional outcomes and lower mortality than medical care alone but led to a higher incidence of symptomatic intracerebral hemorrhage. (Funded by Montpellier University Hospital; LASTE ClinicalTrials.gov number, NCT03811769.)., (Copyright © 2024 Massachusetts Medical Society.)

Background: Performing endovascular treatment (EVT) in patients with acute ischemic stroke (AIS) allows a port of entry for intracranial biological sampling., Objective: To test the hypothesis that specific immune players are molecular contributors to disease, outcome biomarkers, and potential targets for modifying AIS., Methods: We examined 75 subjects presenting with large vessel occlusion of the anterior circulation and undergoing EVT. Intracranial blood samples were obtained by microcatheter aspiration, as positioned for stent deployment. Peripheral blood samples were collected from the femoral artery. Plasma samples were quality controlled by electrophoresis and analyzed using a Mesoscale multiplex for targeted inflammatory and vascular factors., Results: We measured 37 protein biomarkers in our sample cohort. Through multivariate analysis, adjusted for age, intravenous thrombolysis, pretreatment National Institutes of Health Stroke Scale and Alberta Stroke Program Early CT scores, we found that post-clot blood levels of interleukin-6 (IL-6) were significantly correlated (adjusted P value <0.05) with disability assessed by the modified Rankin Scale (mRS) score at 90 days, with medium effect size. Chemokine (C-C) ligand 17 CCL17/TARC levels were inversely correlated with the mRS score. Examination of peripheral blood showed that these correlations did not reach statistical significance after correction. Intracranial biomarker IL-6 level was specifically associated with a lower likelihood of favorable outcome, defined as a mRS score of 0-2., Conclusions: Our findings show a signature of blood inflammatory factors at the cerebrovascular occlusion site. The correlations between these acute-stage biomarkers and mRS score outcome support an avenue for add-on and localized immune modulatory strategies in AIS., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The clinical benefit of mechanical thrombectomy(MT) for stroke patients with tandem occlusion is similar to that of isolated intracranial occlusions. However, the management of cervical internal carotid artery(ICA) occlusion during the MT, particularly in the setting of carotid dissection, remains controversial. We aimed to investigate the clinical impact of cervical ICA patency at day 1 on 3-month functional outcome., Methods: We collected data from the Endovascular Treatment in Ischemic Stroke, a prospective national registry in 30 French centers performing MT between January 2015 and January 2022. Inclusion criteria were consecutive tandem occlusions related to cervical ICA dissection treated with MT. Tandem occlusions of other etiology, isolated cervical ICA occlusions without intracranial thrombus and patients without day-1 ICA imaging were excluded. Primary endpoint was the 3-month functional outcome. Secondary endpoints included intracranial hemorrhage(ICH), excellent outcome, mortality and early neurological improvement. A sensitivity analysis was performed in patients with intracranial favorable recanalization after MT., Results: During the study period, 137 patients were included of which 89(65%) presented ICA patency at day 1. The odds of favorable outcome did not significantly differ between patients with patent and occluded ICA at day 1(68.7 vs 59.1%;aOR=1.30;95%CI 0.56-3.00,p=0.54). Excellent outcome, early neurological improvement, mortality and ICH were also comparable between groups. Sensitivity analysis showed similar results., Conclusion: ICA patency at day 1 in patients with tandem occlusions related to dissection did not seem to influence functional outcome. Endovascular recanalization of the cervical ICA including stenting might not be systematically required in this setting., Competing Interests: Declaration of competing interest The authors have no disclosure related to the present publication., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Background: Tandem occlusions are a singular large vessel occlusion entity involving specific endovascular and perioperative antithrombotic management. In this context, data on safety and efficacy of prior intravenous thrombolysis (IVT) with tenecteplase is scarce. We aimed to compare IVT with tenecteplase or alteplase in patients with acute tandem occlusions intended for endovascular treatment., Patients and Methods: A retrospective pooled analysis of two large observational registries (ETIS (Endovascular Treatment of Ischemic Stroke) and TETRIS (Tenecteplase Treatment in Ischemic Stroke)) was performed on consecutive patients presenting with anterior circulation tandem occlusion treated with IVT using either alteplase (ETIS) or tenecteplase (TETRIS) followed by endovascular treatment between January 2015 and June 2022. Sensitivity analyses on atherosclerosis related tandem occlusions and on patient treated with emergent carotid stenting were conducted. Propensity score overlap weighting analyses were performed., Results: We analyzed 753 patients: 124 in the tenecteplase and 629 in the alteplase group. The overall odds of favorable outcome (3-month modified Rankin score 0-2) were comparable between both groups (49.4% vs 47.1%; OR = 1.10, 95%CI 0.85-1.41). Early recanalization, final successful recanalization and mortality favored the use of tenecteplase. The occurrence of any intracranial hemorrhage (ICH) was more frequent after tenecteplase use (OR = 2.24; 95%CI 1.75-2.86). However, risks of symptomatic ICH and parenchymal hematoma remained similar. In atherosclerotic tandems, favorable outcome, mortality, parenchymal hematoma, early recanalization, and final successful recanalization favored the tenecteplase group. In the carotid stenting subgroup, PH were less frequent in the tenecteplase group (OR = 0.18; 95%CI 0.05-0.69)., Conclusion: In patients with tandem occlusions, IVT with tenecteplase seemed reasonably safe in particular with increased early recanalization rates. These findings remain preliminary and should be further confirmed in randomized trials., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: The choice of the first-line technique in vertebrobasilar occlusions (VBOs) remains challenging. We aimed to report outcomes in a large cohort of patients and to compare the efficacy and safety of contact aspiration (CA) and combined technique (CoT) as a first-line endovascular technique in patients with acute VBOs., Methods: We retrospectively analyzed clinical and neuroradiological data of patients with VBOs from the prospective, multicenter, observational Endovascular Treatment in Ischemic Stroke (ETIS) Registry in France between January 2015 and August 2023. The primary outcome was the first pass effect (FPE) rate, whereas modified Thrombolysis In Cerebral Infarction (mTICI) 2b-3 and 2c-3, number of passes, need for rescue strategy, modified Rankin Scale (mRS) 0-2, mortality, and symptomatic intracranial hemorrhage (sICH) were secondary outcomes. We performed univariate and multivariate analyses to investigate differences between the two groups., Results: Among the 583 included patients (mean age 66.2 years, median National Institutes of Health Stroke Scale (NIHSS) 13, median posterior circulation Alberta Stroke Program Early CT Score (pc-ASPECTS) 8), 393 were treated with CA alone and 190 with CoT. Procedures performed with CA were shorter compared with CoT (28 vs 47 min, P<0.0001); however, no differences were observed in terms of FPE (CA 43.3% vs CoT 38.4%, P=0.99), and successful final recanalization (mTICI 2b-3, CA 92.4% vs CoT 91.8%, P=0.74) did not differ between the two groups. Functional independence and sICH rates were also similar, whereas mortality was significantly lower in the CA group (34.5% vs 42.9%; OR 1.79, 95% CI 1.03 to 3.11)., Conclusions: We observed no differences in FPE, mTICI 2b-3, sICH, and functional independence between the two study groups. First-line CA was associated with shorter procedures and lower mortality rates than CoT., Competing Interests: Competing interests: JC is a consultant for Balt, Medtronic, Stryker. GM is a consultant for Balt USA, Bracco Imaging, Johnson&Johnson Medical Devices&Diagnostics Group, Medtronic, MicroVention, Phenox, Stryker., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The aim of this study was to report the results of a subgroup analysis of the ASTER2 trial (Effect of Thrombectomy With Combined Contact Aspiration and Stent Retriever vs Stent Retriever Alone on Revascularization in Patients With Acute Ischemic Stroke and Large Vessel Occlusion) comparing the safety and efficacy of the combined technique (CoT) and stent retriever as a first-line approach in internal carotid artery (ICA) terminus±M1-middle cerebral artery (M1-MCA) and isolated M1-MCA occlusions., Methods: Patients enrolled in the ASTER2 trial with ICA terminus±M1-MCA and isolated M1-MCA occlusions were included in this subgroup analysis. The effect of first-line CoT versus stent retriever according to the occlusion site was assessed on angiographic (first-pass effect, expanded Treatment in Cerebral Infarction score ≥2b50, and expanded Treatment in Cerebral Infarction score ≥2c grades at the end of the first-line strategy and at the end of the procedure) and clinicoradiological outcomes (24-hour National Institutes of Health Stroke Scale, ECASS-III [European Cooperative Acute Stroke Study] grades, and 3-month modified Rankin Scale)., Results: Three hundred sixty-two patients were included in the postsubgroup analysis according to the occlusion site: 299 were treated for isolated M1-MCA occlusion (150 with first-line CoT) and 63 were treated for ICA terminus±M1-MCA occlusion (30 with first-line CoT). Expanded Treatment in Cerebral Infarction score ≥2b50 (odds ratio, 11.83 [95% CI, 2.32-60.12]) and expanded Treatment in Cerebral Infarction score ≥2c (odds ratio, 4.09 [95% CI, 1.39-11.94]) were significantly higher in first-line CoT compared with first-line stent retriever in patients with ICA terminus±M1-MCA occlusion but not in patients with isolated M1-MCA., Conclusions: First-line CoT was associated with higher reperfusion grades in patients with ICA terminus±M1-MCA at the end of the procedure., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03290885., Competing Interests: Disclosures Dr Clarençon is a consultant for Artedrone, Balt USA, Medtronic, Penumbra, and Stryker. Dr Caroff is a consultant for Balt USA, Medtronic, and Stryker. Dr Marnat is a consultant for Balt USA, Bracco Imaging, Johnson & Johnson Medical Devices & Diagnostics Group, Medtronic, MicroVention, phenox, and Stryker. Dr Barreau is a consultant for MicroVention. Dr Spelle is a consultant for Balt USA, Medtronic, MicroVention, phenox, and Stryker. The other authors report no conflicts.

Background: Predicting a challenging clot when performing mechanical thrombectomy in acute stroke can be difficult. One reason for this difficulty is a lack of agreement on how to precisely define these clots. We explored the opinions of stroke thrombectomy and clot research experts regarding challenging clots, defined as difficult to recanalize clots by endovascular approaches, and clot/patient features that may be indicative of such clots., Methods: A modified DELPHI technique was used before and during the CLOTS 7.0 Summit, which included experts in thrombectomy and clot research from different specialties. The first round included open-ended questions and the second and final rounds each consisted of 30 closed-ended questions, 29 on various clinical and clot features, and 1 on number of passes before switching techniques. Consensus was defined as agreement ≥ 50%. Features with consensus and rated ≥ 3 out of 4 on the certainty scale were included in the definition of a challenging clot., Results: Three DELPHI rounds were performed. Panelists achieved consensus on 16/30 questions, of which 8 were rated 3 or 4 on the certainty scale, namely white-colored clots (mean certainty score 3.1), calcified clots under histology (3.7) and imaging (3.7), stiff clots (3.0), sticky/adherent clots (3.1), hard clots (3.1), difficult to pass clots (3.1) and clots that are resistant to pulling (3.0). Most panelists considered switching endovascular treatment (EVT) techniques after 2-3 unsuccessful attempts., Conclusion: This DELPHI consensus identified 8 distinct features of a challenging clot. The varying degree of certainty amongst the panelists emphasizes the need for more pragmatic studies to enable accurate a priori identification of such occlusions prior to EVT., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)