Arterial Recanalization During Interhospital Transfer for Thrombectomy.

BACKGROUND: Patients with acute ischemic stroke harboring a large vessel occlusion admitted to nonendovascular-capable centers often require interhospital transfer for thrombectomy. We evaluated the incidence and predictors of arterial recanalization during transfer, as well as the relationship between interhospital recanalization and clinical outcomes. METHODS: We analyzed data from 2 cohorts of patients with an anterior circulation large vessel occlusion transferred for consideration of thrombectomy to a comprehensive center, with arterial imaging at the referring hospital and on comprehensive stroke center arrival. Interhospital recanalization was determined by comparison of the baseline and posttransfer arterial imaging and was defined as revised arterial occlusive lesion (rAOL) score 2b to 3. Pretransfer variables independently associated with interhospital recanalization were studied using multivariable logistic regression analysis. RESULTS: Of the 520 included patients (Montpellier, France, n=237; Stanford, United States, n=283), 111 (21%) experienced interhospital recanalization (partial [rAOL=2b] in 77% and complete [rAOL=3] in 23%). Pretransfer variables independently associated with recanalization were intravenous thrombolysis (adjusted odds ratio, 6.8 [95% CI, 4.0-11.6]), more distal occlusions (intracranial carotid occlusion as reference: adjusted odds ratio, 2.0 [95% CI, 0.9-4.5] for proximal first segment of the middle cerebral artery, 5.1 [95% CI, 2.3-11.5] for distal first segment of the middle cerebral artery, and 5.0 [95% CI, 2.1-11.8] for second segment of the middle cerebral artery), and smaller clot burden (clot burden score 0-4 as reference: adjusted odds ratio, 3.4 [95% CI, 1.5-7.6] for 5-7 and 5.6 [95% CI, 2.4-12.7] for 8-9). Recanalization on arrival at the comprehensive center was associated with less interhospital infarct growth (rAOL, 0-2a: 11.6 mL; rAOL, 2b: 2.2 mL; rAOL, 3: 0.6 mL; Ptrend<0.001) and greater interhospital National Institutes of Health Stroke Scale score improvement (0 versus -5 versus -6; Ptrend<0.001). Interhospital recanalization was associated with reduced 3-month disability (adjusted common odds ratio, 2.51 [95% CI, 1.68-3.77]) with greater benefit from complete than partial recanalization. CONCLUSIONS: Recanalization is frequently observed during interhospital transfer for thrombectomy and is strongly associated with favorable outcomes, even when partial. Broadening thrombolysis indications in primary centers, and developing therapies that increase recanalization during transfer, will likely improve clinical outcomes.

Does imaging of the ischemic penumbra have value in acute ischemic stroke with large vessel occlusion?

PURPOSE OF REVIEW: In this review, we summarize current evidence regarding potential benefits and limitations of using perfusion imaging to estimate presence and extent of irreversibly injured ischemic brain tissue ('core') and severely ischemic yet salvageable tissue ('penumbra') in acute stroke patients with large vessel occlusion (LVO). RECENT FINDINGS: Core and penumbra volumes are strong prognostic biomarkers in LVO patients. Greater benefits of both intravenous thrombolysis and endovascular therapy (EVT) are observed in patients with small core and large penumbra volumes. However, some current definitions of clinically relevant penumbra may be too restrictive and exclude patients who may benefit from reperfusion therapies. Alongside other clinical and radiological factors, penumbral imaging may enhance the discussion regarding the benefit/risk ratio of EVT in common clinical situations, such as patients with large core - for whom EVT's benefit is established but associated with a high rate of severe disability -, or patients with mild symptoms or medium vessel occlusions - for whom EVT's benefit is currently unknown. Beyond penumbral evaluation, perfusion imaging is clinically relevant for optimizing patient's selection for neuroprotection trials. SUMMARY: In an emerging era of precision medicine, perfusion imaging is a valuable tool in LVO-related acute stroke.

Determinants of Infarct Core Growth During Inter-hospital Transfer for Thrombectomy.

OBJECTIVE: Patients with acute ischemic stroke harboring a large vessel occlusion who present to primary stroke centers often require inter-hospital transfer for thrombectomy. We aimed to determine clinical and imaging factors independently associated with fast infarct growth (IG) during inter-hospital transfer. METHODS: We retrospectively analyzed data from acute stroke patients with a large vessel occlusion transferred for thrombectomy from a primary stroke center to one of three French comprehensive stroke centers, with an MRI obtained at both the primary and comprehensive center before thrombectomy. Inter-hospital IG rate was defined as the difference in infarct volumes on diffusion-weighted imaging between the primary and comprehensive center, divided by the delay between the two MRI scans. The primary outcome was identification of fast progressors, defined as IG rate ≥5 mL/hour. The hypoperfusion intensity ratio (HIR), a surrogate marker of collateral blood flow, was automatically measured on perfusion imaging. RESULTS: A total of 233 patients were included, of whom 27% patients were fast progressors. The percentage of fast progressors was 3% among patients with HIR < 0.40 and 71% among those with HIR ≥ 0.40. In multivariable analysis, fast progression was independently associated with HIR, intracranial carotid artery occlusion, and exclusively deep infarct location at the primary center (C-statistic = 0.95; 95% confidence interval [CI], 0.93-0.98). IG rate was independently associated with good functional outcome (adjusted OR = 0.91; 95% CI, 0.83-0.99; P = 0.037). INTERPRETATION: Our findings show that a HIR > 0.40 is a powerful indicator of fast inter-hospital IG. These results have implication for neuroprotection trial design, as well as informing triage decisions at primary stroke centers. ANN NEUROL 2023;93:1117-1129.

Inter-hospital transfer for thrombectomy: transfer time is brain.

BACKGROUND AND PURPOSE: Patients with acute ischaemic stroke and a large vessel occlusion who present to a non-endovascular-capable centre often require inter-hospital transfer for thrombectomy. Whether the inter-hospital transfer time is associated with 3-month functional outcome is poorly known. METHODS: Acute stroke patients enrolled between January 2015 and December 2022 in the prospective French multicentre Endovascular Treatment of Ischaemic Stroke registry were retrospectively analysed. Patients with an anterior circulation large vessel occlusion transferred from a non-endovascular to a comprehensive stroke centre for thrombectomy were eligible. Inter-hospital transfer time was defined as the time between imaging in the referring hospital and groin puncture for thrombectomy. The relationship between transfer time and favourable 3-month functional outcome (modified Rankin Scale 0-2) was assessed through a mixed logistic regression model adjusting for centre and symptom-onset-to-referring-hospital imaging time, age, sex, diabetes, referring hospital National Institutes of Health Stroke Scale score, Alberta Stroke Programme Early Computed Tomography Score, occlusion site and intravenous thrombolysis use. RESULTS: Overall, 3769 patients were included (median inter-hospital transfer time 161 min, interquartile range 128-195; 46% with favourable outcome). A longer transfer time was independently associated with lower rates of favourable outcome (p < 0.001). Compared to patients with transfer time below 120 min, there was a 15% reduction in the odds of achieving favourable outcome for transfer times between 120 and 180 min (adjusted odds ratio 0.85; 95% confidence interval 0.67-1.07), and a 36% reduction for transfer times beyond 180 min (adjusted odds ratio 0.64; 95% confidence interval 0.50-0.81). CONCLUSIONS: A shorter inter-hospital transfer time is strongly associated with favourable 3-month functional outcome. A speedier inter-hospital transfer is of critical importance to improve outcome.

Early Recanalization Among Patients Undergoing Bridging Therapy With Tenecteplase or Alteplase.

BACKGROUND: Intravenous thrombolysis (IVT) with alteplase or tenecteplase before mechanical thrombectomy is the recommended treatment for large-vessel occlusion acute ischemic stroke. There are divergent data on whether these agents differ in terms of early recanalization (ER) rates before mechanical thrombectomy, and little data on their potential differences stratified by ER predictors such as IVT to ER evaluation (IVT-to-EReval) time, occlusion site and thrombus length. METHODS: We retrospectively compared the likelihood of ER after IVT with tenecteplase or alteplase in anterior circulation large-vessel occlusion acute ischemic stroke patients from the PREDICT-RECANAL (alteplase) and Tenecteplase Treatment in Ischemic Stroke (tenecteplase) French multicenter registries. ER was defined as a modified Thrombolysis in Cerebral Infarction score 2b-3 on the first angiographic run, or noninvasive vascular imaging in patients with early neurological improvement. Analyses were based on propensity score overlap weighting (leading to exact balance in patient history, stroke characteristics, and initial management between groups) and confirmed with adjusted logistic regression (sensitivity analysis). A stratified analysis based on pre-established ER predictors (IVT-to-EReval time, occlusion site, and thrombus length) was conducted. RESULTS: Overall, 1865 patients were included. ER occurred in 156/787 (19.8%) and 199/1078 (18.5%) patients treated with tenecteplase or alteplase, respectively (odds ratio, 1.09 [95% CI, 0.83-1.44]; P=0.52). A differential effect of tenecteplase versus alteplase on the probability of ER according to thrombus length was observed (Pinteraction=0.003), with tenecteplase being associated with higher odds of ER in thrombi >10 mm (odds ratio, 2.43 [95% CI, 1.02-5.81]; P=0.04). There was no differential effect of tenecteplase versus alteplase on the likelihood of ER according to the IVT-to-EReval time (Pinteraction=0.40) or occlusion site (Pinteraction=0.80). CONCLUSIONS: Both thrombolytics achieved ER in one-fifth of patients with large-vessel occlusion acute ischemic stroke without significant interaction with IVT-to-EReval time and occlusion site. Compared with alteplase, tenecteplase was associated with a 2-fold higher likelihood of ER in larger thrombi.

Infarct Core Growth During Interhospital Transfer For Thrombectomy Is Faster At Night.

BACKGROUND: Preclinical stroke models have recently reported faster infarct growth (IG) when ischemia was induced during daytime. Considering the inverse rest-activity cycles of rodents and humans, faster IG during the nighttime has been hypothesized in humans. METHODS: We retrospectively evaluated acute ischemic stroke patients with a large vessel occlusion transferred from a primary to 1 of 3 French comprehensive stroke center, with magnetic resonance imaging obtained at both centers before thrombectomy. Interhospital IG rate was calculated as the difference in infarct volumes on the 2 diffusion-weighted imaging, divided by the time elapsed between the 2 magnetic resonance imaging. IG rate was compared between patients transferred during daytime (7:00-22:59) and nighttime (23:00-06:59) in multivariable analysis adjusting for occlusion site, National Institutes of Health Stroke Scale score, infarct topography, and collateral status. RESULTS: Out of the 329 patients screened, 225 patients were included. Interhospital transfer occurred during nighttime in 31 (14%) patients and daytime in 194 (86%). Median interhospital IG was faster when occurring at night (4.3 mL/h; interquartile range, 1.2-9.5) as compared to the day (1.4 mL/h; interquartile range, 0.4-3.5; P<0.001). In multivariable analysis, nighttime transfer remained independently associated with IG rate (P<0.05). CONCLUSIONS: Interhospital IG appeared faster in patients transferred at night. This has potential implications for the design of neuroprotection trials and acute stroke workflow.

Role of Brain Imaging in the Prediction of Intracerebral Hemorrhage Following Endovascular Therapy for Acute Stroke.

Currently most acute ischemic stroke patients presenting with a large vessel occlusion are treated with endovascular therapy (EVT), which results in high rates of successful recanalization. Despite this success, more than half of EVT-treated patients are significantly disabled 3 months later partly due to the occurrence of post-EVT intracerebral hemorrhage. Predicting post-EVT intracerebral hemorrhage is important for individualizing treatment strategies in clinical practice (eg, safe initiation of early antithrombotic therapies), as well as in selecting the optimal candidates for clinical trials that aim to reduce this deleterious outcome. Emerging data suggest that brain and vascular imaging biomarkers may be particularly relevant since they provide insights into the ongoing acute stroke pathophysiology. In this review/perspective, we summarize the accumulating literature on the role of cerebrovascular imaging biomarkers in predicting post-EVT-associated intracerebral hemorrhage. We focus on imaging acquired before EVT, during the EVT procedure, and in the early post-EVT time frames when new therapeutic therapies could be tested. Accounting for the complex pathophysiology of post-EVT-associated intracerebral hemorrhage, this review may provide some guidance for future prospective observational or therapeutic studies.

Consensus Recommendations for Standardized Data Elements, Scales, and Time Segmentations in Studies of Human Circadian/Diurnal Biology and Stroke.

Increasing evidence indicates that circadian and diurnal rhythms robustly influence stroke onset, mechanism, progression, recovery, and response to therapy in human patients. Pioneering initial investigations yielded important insights but were often single-center series, used basic imaging approaches, and used conflicting definitions of key data elements, including what constitutes daytime versus nighttime. Contemporary methodologic advances in human neurovascular investigation have the potential to substantially increase understanding, including the use of large multicenter and national data registries, detailed clinical trial data sets, analysis guided by individual patient chronotype, and multimodal computed tomographic and magnetic resonance imaging. To fully harness the power of these approaches to enhance pathophysiologic knowledge, an important foundational step is to develop standardized definitions and coding guides for data collection, permitting rapid aggregation of data acquired in different studies, and ensuring a common framework for analysis. To meet this need, the Leducq Consortium International pour la Recherche Circadienne sur l'AVC (CIRCA) convened a Consensus Statement Working Group of leading international researchers in cerebrovascular and circadian/diurnal biology. Using an iterative, mixed-methods process, the working group developed 79 data standards, including 48 common data elements (23 new and 25 modified/unmodified from existing common data elements), 14 intervals for time-anchored analyses of different granularity, and 7 formal, validated scales. This portfolio of standardized data structures is now available to assist researchers in the design, implementation, aggregation, and interpretation of clinical, imaging, and population research related to the influence of human circadian/diurnal biology upon ischemic and hemorrhagic stroke.

Endovascular Therapy or Medical Management Alone for Isolated Posterior Cerebral Artery Occlusion: A Multicenter Study.

BACKGROUND: Whether endovascular therapy (EVT) added on best medical management (BMM), as compared to BMM alone, is beneficial in acute ischemic stroke with isolated posterior cerebral artery occlusion is unknown. METHODS: We conducted a multicenter international observational study of consecutive stroke patients admitted within 6 hours from symptoms onset in 26 stroke centers with isolated occlusion of the first (P1) or second (P2) segment of the posterior cerebral artery and treated either with BMM+EVT or BMM alone. Propensity score with inverse probability of treatment weighting was used to account for baseline between-groups differences. The primary outcome was 3-month good functional outcome (modified Rankin Scale [mRS] score 0-2 or return to baseline modified Rankin Scale). Secondary outcomes were 3-month excellent recovery (modified Rankin Scale score 0-1), symptomatic intracranial hemorrhage, and early neurological deterioration. RESULTS: Overall, 752 patients were included (167 and 585 patients in the BMM+EVT and BMM alone groups, respectively). Median age was 74 (interquartile range, 63-82) years, 329 (44%) patients were female, median National Institutes of Health Stroke Scale was 6 (interquartile range 4-10), and occlusion site was P1 in 188 (25%) and P2 in 564 (75%) patients. Baseline clinical and radiological data were similar between the 2 groups following propensity score weighting. EVT was associated with a trend towards lower odds of good functional outcome (odds ratio, 0.81 [95% CI, 0.66-1.01]; P=0.06) and was not associated with excellent functional outcome (odds ratio, 1.17 [95% CI, 0.95-1.43]; P=0.15). EVT was associated with a higher risk of symptomatic intracranial hemorrhage (odds ratio, 2.51 [95% CI, 1.35-4.67]; P=0.004) and early neurological deterioration (odds ratio, 2.51 [95% CI, 1.64-3.84]; P<0.0001). CONCLUSIONS: In this observational study of patients with proximal posterior cerebral artery occlusion, EVT was not associated with good or excellent functional outcome as compared to BMM alone. However, EVT was associated with higher rates of symptomatic intracranial hemorrhage and early neurological deterioration. EVT should not be routinely recommended in this population, but randomization into a clinical trial is highly warranted.

Relevance of National Institutes of Health Stroke Scale subitems for best revascularization therapy in minor stroke patients with large vessel occlusion: An observational multicentric study.

BACKGROUND AND PURPOSE: The best management of acute ischemic stroke patients with a minor stroke and large vessel occlusion is still uncertain. Specific clinical and radiological data may help to select patients who would benefit from endovascular therapy (EVT). We aimed to evaluate the relevance of National Institutes of Health Stroke Scale (NIHSS) subitems for predicting the potential benefit of providing EVT after intravenous thrombolysis (IVT; "bridging treatment") versus IVT alone. METHODS: We extracted demographic, clinical, risk factor, radiological, revascularization and outcome data of consecutive patients with M1 or proximal M2 middle cerebral artery occlusion and admission NIHSS scores of 0-5 points, treated with IVT ± EVT between May 2005 and March 2021, from nine prospectively constructed stroke registries at seven French and two Swiss comprehensive stroke centers. Adjusted interaction analyses were performed between admission NIHSS subitems and revascularization modality for two primary outcomes at 3 months: non-excellent functional outcome (modified Rankin Scale score 2-6) and difference in NIHSS score between 3 months and admission. RESULTS: Of the 533 patients included (median age 68.2 years, 46% women, median admission NIHSS score 3), 136 (25.5%) initially received bridging therapy and 397 (74.5%) received IVT alone. Adjusted interaction analysis revealed that only facial palsy on admission was more frequently associated with excellent outcome in patients treated by IVT alone versus bridging therapy (odds ratio 0.47, 95% confidence interval 0.24-0.91; p = 0.013). Regarding NIHSS difference at 3 months, no single NIHSS subitem interacted with type of revascularization. CONCLUSIONS: This retrospective multicenter analysis found that NIHSS subitems at admission had little value in predicting patients who might benefit from bridging therapy as opposed to IVT alone. Further research is needed to identify better markers for selecting EVT responders with minor strokes.

Elevated Hypoperfusion Intensity Ratio (HIR) observed in patients with a large vessel occlusion (LVO) presenting in the evening.

BACKGROUND: Circadian variability has been implicated in timing of stroke onset, yet the full impact of underlying biological rhythms on acute stroke perfusion patterns is not known. We aimed to describe the relationship between time of stroke onset and perfusion profiles in patients with large vessel occlusion (LVO). METHODS: A retrospective observational study was conducted using prospective registries of four stroke centers across North America and Europe with systematic use of perfusion imaging in clinical care. Included patients had stroke due to ICA, M1 or M2 occlusion and baseline perfusion imaging performed within 24h from last-seen-well (LSW). Stroke onset was divided into eight hour intervals: (1) Night: 23:00-6:59, (2) Day: 7:00-14:59, (3) Evening: 15:00-22:59. Core volume was estimated on CT perfusion (rCBF <30%) or DWI-MRI (ADC <620) and the collateral circulation was estimated with the Hypoperfusion Intensity Ratio (HIR = [Tmax>10s]/[Tmax>6s]). Non-parametric testing was conducted using SPSS to account for the non-normalized dependent variables. RESULTS: A total of 1506 cases were included (median age 74.9 years, IQR 63.0-84.0). Median NIHSS, core volumes, and HIR were 14.0 (IQR 8.0-20.0), 13.0mL (IQR 0.0-42.0), and 0.4 (IQR 0.2-0.6) respectively. Most strokes occurred during the Day (n = 666, 44.2%), compared to Night (n = 360, 23.9%), and Evening (n = 480, 31.9%). HIR was highest, indicating worse collaterals, in the Evening compared to the other timepoints (p = 0.006). Controlling for age and time to imaging, Evening strokes had significantly higher HIR compared to Day (p = 0.013). CONCLUSION: Our retrospective analysis suggests that HIR is significantly higher in the evening, indicating poorer collateral activation which may lead to larger core volumes in these patients.

Larger ischemic cores and poor collaterals among large vessel occlusions presenting in the late evening.

BACKGROUND: Components critical to cerebral perfusion have been noted to oscillate over a 24-h cycle. We previously reported that ischemic core volume has a diurnal relationship with stroke onset time when examined as dichotomized epochs (i.e. Day, Evening, Night) in a cohort of over 1,500 large vessel occlusion (LVO) patients. In this follow-up analysis, our goal was to explore if there is a sinusoidal relationship between ischemic core, collateral status (as measured by HIR), and stroke onset time. METHODS: We retrospectively examined collection of LVO patients with baseline perfusion imaging performed within 24 h of stroke onset from four international comprehensive stroke centers. Both ischemic core volume and HIR, were utilized as the primary radiographic parameters. To evaluate for differences in these parameters over a continuous 24-h cycle, we conducted a sinusoidal regression analysis after linearly regressing out the confounders age and time to imaging. RESULTS: A total of 1506 LVO cases were included, with a median ischemic core volume of 13.0 cc (IQR: 0.0-42.0) and median HIR of 0.4 (IQR: 0.2-0.6). Ischemic core volume varied by stroke onset time in the unadjusted (p = 0.001) and adjusted (p = 0.003) sinusoidal regression analysis with a peak in core volume around 7:45PM. HIR similarly varied by stroke onset time in the unadjusted (p = 0.004) and adjusted (p = 0.002) models with a peak in HIR values at around 8:18PM. CONCLUSION: The results suggest that critical factors to the development of the ischemic core vary by stroke onset time and peak around 8PM. When placed in the context of prior studies, strongly suggest a diurnal component to the development of the ischemic core.

Should Patients With Acute Minor Ischemic Stroke With Isolated Internal Carotid Artery Occlusion Be Thrombolysed?

BACKGROUND: We recently reported a worrying 30% rate of early neurological deterioration (END) occurring within 24 hours following intravenous thrombolysis (IVT) in minor stroke with isolated internal carotid artery occlusion (ie, without additional intracranial occlusion), mainly due to artery-to-artery embolism. Here, we hypothesize that in this setting IVT-as compared to no-IVT-may foster END, in particular by favoring artery-to-artery embolism from thrombus fragmentation. METHODS: From a large multicenter retrospective database, we compared minor stroke (National Institutes of Health Stroke Scale score <6) isolated internal carotid artery occlusion patients treated within 4.5 hours of symptoms onset with either IVT or antithrombotic therapy between 2006 and 2020 (inclusion date varied among centers). Primary outcome was END within 24 hours (≥4 National Institutes of Health Stroke Scale points increase within 24 hours), and secondary outcomes were END within 7 days (END7d) and 3-month modified Rankin Scale score 0 to 1. RESULTS: Overall, 189 patients were included (IVT=95; antithrombotics=94 [antiplatelets, n=58, anticoagulants, n=36]) from 34 centers. END within 24 hours and END7d occurred in 46 (24%) and 60 (32%) patients, respectively. Baseline clinical and radiological variables were similar between the 2 groups, except significantly higher National Institutes of Health Stroke Scale (median 3 versus 2) and shorter onset-to-imaging (124 versus 149min) in the IVT group. END within 24 hours was more frequent following IVT (33% versus 16%, adjusted hazard ratio, 2.01 [95% CI, 1.07-3.92]; P=0.03), driven by higher odds of artery-to-artery embolism (20% versus 9%, P=0.09). However, END7d and 3-month modified Rankin Scale score of 0 to 1 did not significantly differ between the 2 groups (END7d: adjusted hazard ratio, 1.29 [95% CI, 0.75-2.23]; P=0.37; modified Rankin Scale score of 0-1: adjusted odds ratio, 1.1 [95% CI, 0.6-2.2]; P=0.71). END7d occurred earlier in the IVT group: median imaging-to-END 2.6 hours (interquartile range, 1.9-10.1) versus 20.4 hours (interquartile range, 7.8-34.4), respectively, P<0.01. CONCLUSIONS: In our population of minor strokes with iICAO, although END rate at 7 days and 3-month outcome were similar between the 2 groups, END-particularly END due to artery-to-artery embolism-occurred earlier following IVT. Prospective studies are warranted to further clarify the benefit/risk profile of IVT in this population.

Perfusion Imaging and Clinical Outcome in Acute Minor Stroke With Large Vessel Occlusion.

BACKGROUND: Whether bridging therapy (intravenous thrombolysis [IVT] followed by mechanical thrombectomy) is superior to IVT alone in minor stroke with large vessel occlusion is unknown. Perfusion imaging may identify subsets of large vessel occlusion-related minor stroke patients with distinct response to bridging therapy. METHODS: We conducted a multicenter international observational study of consecutive IVT-treated patients with minor stroke (National Institutes of Health Stroke Scale score ≤5) who had an anterior circulation large vessel occlusion and perfusion imaging performed before IVT, with a subset undergoing immediate thrombectomy. Propensity score with inverse probability of treatment weighting was used to account for baseline between-groups differences. The primary outcome was 3-month modified Rankin Scale score 0 to 1. We searched for an interaction between treatment group and mismatch volume (critical hypoperfusion-core volume). RESULTS: Overall, 569 patients were included (172 and 397 in the bridging therapy and IVT groups, respectively). After propensity-score weighting, the distribution of baseline variables was similar across the 2 groups. In the entire population, bridging was associated with lower odds of achieving modified Rankin Scale score 0 to 1: odds ratio, 0.73 [95% CI, 0.55-0.96]; P=0.03. However, mismatch volume modified the effect of bridging on clinical outcome (Pinteraction=0.04 for continuous mismatch volume); bridging was associated with worse outcome in patients with, but not in those without, mismatch volume <40 mL (odds ratio, [95% CI] for modified Rankin Scale score 0-1: 0.48 [0.33-0.71] versus 1.14 [0.76-1.71], respectively). Bridging was associated with higher incidence of symptomatic intracranial hemorrhage in the entire population, but this effect was present in the small mismatch subset only (Pinteraction=0.002). CONCLUSIONS: In our population of large vessel occlusion-related minor stroke patients, bridging therapy was associated with lower rates of good outcome as compared with IVT alone. However, mismatch volume was a strong modifier of the effect of bridging therapy over IVT alone, notably with worse outcome with bridging therapy in patients with mismatch volume ≤40 mL. Randomized trials should consider adding perfusion imaging for patient selection.

Perfusion Imaging and Clinical Outcome in Acute Ischemic Stroke with Large Core.

OBJECTIVE: Mechanical thrombectomy (MT) is not recommended for acute stroke with large vessel occlusion (LVO) and a large volume of irreversibly injured tissue ("core"). Perfusion imaging may identify a subset of patients with large core who benefit from MT. METHODS: We compared two cohorts of LVO-related patients with large core (>50 ml on diffusion-weighted-imaging or CT-perfusion using RAPID), available perfusion imaging, and treated within 6 hours from onset by either MT + Best Medical Management (BMM) in one prospective study, or BMM alone in the pre-MT era from a prospective registry. Primary outcome was 90-day modified Rankin Scale ≤2. We searched for an interaction between treatment group and amount of penumbra as estimated by the mismatch ratio (MMRatio = critical hypoperfusion/core volume). RESULTS: Overall, 107 patients were included (56 MT + BMM and 51 BMM): Mean age was 68 ± 15 years, median core volume 99 ml (IQR: 72-131) and MMRatio 1.4 (IQR: 1.0-1.9). Baseline clinical and radiological variables were similar between the two groups, except for a higher intravenous thrombolysis rate in the BMM group. The MMRatio strongly modified the clinical outcome following MT (pinteraction < 0.001 for continuous MMRatio); MT was associated with a higher rate of good outcome in patients with, but not in those without, MMRatio>1.2 (adjusted OR [95% CI] = 6.8 [1.7-27.0] vs 0.7 [0.1-6.2], respectively). Similar findings were present for MMRatio ≥1.8 in the subgroup with core ≥70 ml. Parenchymal hemorrhage on follow-up imaging was more frequent in the MT + BMM group regardless of the MMRatio. INTERPRETATION: Perfusion imaging may help select which patients with large core should be considered for MT. Randomized studies are warranted. ANN NEUROL 2021;90:417-427.

Intended Bridging Therapy or Intravenous Thrombolysis Alone in Minor Stroke With Basilar Artery Occlusion.

BACKGROUND AND PURPOSE: Whether bridging therapy (intravenous thrombolysis [IVT] followed by mechanical thrombectomy) is superior to IVT alone in minor stroke with basilar artery occlusion remains uncertain. METHODS: Multicentric retrospective observational study of consecutive minor stroke patients (National Institutes of Health Stroke Scale score ≤5) with basilar artery occlusion intended for IVT alone or bridging therapy. Propensity-score weighting was used to reduce baseline between-groups differences, and residual imbalance was addressed through adjusted logistic regression, with excellent outcome (3-month modified Rankin Scale score 0-1) as the dependent variable. RESULTS: Fifty-seven patients were included (28 and 29 in the bridging therapy and IVT alone groups, respectively). Following propensity-score weighting, the distribution of baseline clinical and radiological variables was similar across the 2 patient groups, except age, posterior circulation Alberta Stroke Program Early CT Score, history of hypertension and smoking, and onset-to-IVT time. Compared with IVT alone, bridging therapy was associated with excellent outcome (adjusted odds ratio=3.37 [95% CI, 1.13-10.03]; P=0.03). No patient experienced symptomatic intracranial hemorrhage. CONCLUSIONS: Our results suggest that bridging therapy may be superior to IVT alone in minor stroke with basilar artery occlusion.

Bridging Therapy or IV Thrombolysis in Minor Stroke with Large Vessel Occlusion.

OBJECTIVE: Whether bridging therapy (intravenous thrombolysis [IVT] followed by endovascular treatment) is superior to IVT alone in minor stroke with large vessel occlusion (LVO) is unknown. METHODS: Multicentric retrospective observational study including, in intention-to-treat, consecutive IVT-treated minor strokes (National Institutes of Health Stroke Scale [NIHSS] ≤ 5) with LVO, with or without additional mechanical thrombectomy. Propensity-score (inverse probability of treatment weighting) was used to reduce baseline between-groups differences. The primary outcome was excellent outcome, that is, modified Rankin score 0 to 1 at 3 months follow-up. RESULTS: Overall, 598 patients were included (214 and 384 in the bridging therapy and IVT groups, respectively). Following propensity-score weighting, the distribution of baseline clinical and radiological variables was similar across the two patient groups. Compared with IVT alone, bridging therapy was not associated with excellent outcome (odds ratio [OR] = 0.96; 95% confidence interval [CI] = 0.75-1.24; p = 0.76), but was associated with symptomatic intracranial hemorrhage (OR = 3.01; 95% CI = 1.77-5.11; p < 0.0001). Occlusion site was a strong modifier of the effect of bridging therapy on outcome (pinteraction < 0.0001), with bridging therapy associated with higher odds of excellent outcome in proximal M1 (OR = 3.26; 95% CI = 1.67-6.35; p = 0.0006) and distal M1 (OR = 1.69; 95% CI = 1.01-2.82; p = 0.04) occlusions, but with lower odds of excellent outcome for M2 (OR = 0.53; 95% CI = 0.38-0.75; p = 0.0003) occlusions. Bridging therapy was associated with higher rates of symptomatic intracranial hemorrhage in M2 occlusions only (OR = 4.40; 95% CI = 2.20-8.83; p < 0.0001). INTERPRETATION: Although overall outcomes were similar in intended bridging therapy as compared to intended IVT alone in minor strokes with LVO, our results suggest that intended bridging therapy may be beneficial in M1 occlusions, whereas the benefit-risk profile may favor IVT alone in M2 occlusions. ANN NEUROL 2020 ANN NEUROL 2020;88:160-169.

Vascular origin in acute transient visual disturbance: A prospective study.

BACKGROUND AND PURPOSE: This study was undertaken to validate a clinical score of vascular origin in patients with acute transient visual disturbances (TVDs) without diplopia. METHODS: We conducted a prospective study in an ophthalmology emergency department and a transient ischemic attack (TIA) clinic. Patients underwent clinical evaluation including a tailored questionnaire, brain, vascular, and ophthalmologic investigations, and 3-month follow-up. TVDs were classified according to vascular or nonvascular origin by three independent experts based on all clinical, cerebrovascular, and ophthalmologic investigations, but blind to the questionnaire results. A clinical score was derived based on clinical variables independently associated with a vascular origin, and was externally validated in an independent cohort. RESULTS: An ischemic origin of TVD was found in 45% (67/149) of patients in the derivation cohort. Age and six questions were independently associated with an ischemic origin. A nine-point score (≥70 years old = 2; monocular visual loss = 2; black or white vision = 1; single episode = 1; lack of headache = 2; diffuse, constricted, altitudinal, or lateralized visual loss pattern on drawings = 1) showed good discriminative power in identifying ischemic origin (c-statistic = 0.82) and was replicated in the validation cohort (n = 130, 25% of ischemic origin, c-statistic = 0.75). With a score ≥ 4, sensitivity was 85% (95% confidence interval = 68-95) and specificity was 52% (95% confidence interval = 41-62). In both cohorts, ophthalmologic evaluation found a vascular cause in 4% and was noncontributive in 85%. After 3 months, no patients had a stroke, TIA, or retinal infarct. CONCLUSIONS: Our score may assist in predicting a vascular origin of TVD. Ophthalmologic evaluation, when not readily available, should not delay the neurovascular evaluation.

3D T1-weighted black-blood magnetic resonance imaging for the diagnosis of giant cell arteritis.

OBJECTIVES: Imaging techniques have an increasing place in the diagnosis of giant cell arteritis (GCA). Achieving a confident diagnosis of GCA is often challenging and temporal artery biopsy is still considered as the gold standard despite the delayed results. 3T-MRI with 2D sequences has been evaluated for the detection of mural inflammation in extracranial arteries to support the diagnosis of GCA. METHODS: We evaluated the diagnostic performance of fat-suppressed 3D T1-weighted black-blood MRI (CUBE T1) with 3D TOF coregistration. RESULTS: Thirty-two patients with clinically suspected GCA were included and 10 had a diagnosis of GCA. Sensitivity and specificity of CUBE T1 were 80% and 100% respectively. Therefore, the positive predictive value of post-contrast CUBE T1 was 100% and the negative predictive value was 92%. Intra- and inter-observer agreement for mural enhancement on CUBE T1 was 1 and 0.83, respectively. CONCLUSIONS: We demonstrate that CUBE T1 is accurate for the diagnosis of GCA. The reproducibility and short scan duration of the technique support a wider use of MRI in the diagnosis process.

Better Collaterals Are Independently Associated With Post-Thrombolysis Recanalization Before Thrombectomy.

Background and Purpose- In acute stroke patients with large vessel occlusion, the goal of intravenous thrombolysis (IVT) is to achieve early recanalization (ER). Apart from occlusion site and thrombus length, predictors of early post-IVT recanalization are poorly known. Better collaterals might also facilitate ER, for instance, by improving delivery of the thrombolytic agent to both ends of the thrombus. In this proof-of-concept study, we tested the hypothesis that good collaterals independently predict post-IVT recanalization before thrombectomy. Methods- Patients from the registries of 6 French stroke centers with the following criteria were included: (1) acute stroke with large vessel occlusion treated with IVT and referred for thrombectomy between May 2015 and March 2017; (2) pre-IVT brain magnetic resonance imaging, including diffusion-weighted imaging, T2*, MR angiography, and dynamic susceptibility contrast perfusion-weighted imaging; and (3) ER evaluated ≤3 hours from IVT start on either first angiographic run or noninvasive imaging. A collateral flow map derived from perfusion-weighted imaging source data was automatically generated, replicating a previously validated method. Thrombus length was measured on T2*-based susceptibility vessel sign. Results- Of 224 eligible patients, 37 (16%) experienced ER. ER occurred in 10 of 83 (12%), 17 of 116 (15%), and 10 of 25 (40%) patients with poor/moderate, good, and excellent collaterals, respectively. In multivariable analysis, better collaterals were independently associated with ER ( P=0.029), together with shorter thrombus ( P<0.001) and more distal occlusion site ( P=0.010). Conclusions- In our sample of patients with stroke imaged with perfusion-weighted imaging before IVT and intended for thrombectomy, better collaterals were independently associated with post-IVT recanalization, supporting our hypothesis. These findings strengthen the idea that advanced imaging may play a key role for personalized medicine in identifying patients with large vessel occlusion most likely to benefit from IVT in the thrombectomy era.