Large vessel occlusive stroke with milder baseline severity shows better collaterals and reduced harm from thrombectomy transfer delays

BACKGROUND

Patients with large vessel occlusion (LVO) stroke presenting with milder baseline clinical severity are common and require endovascular thrombectomy. However, such patients are difficult to recognize using pre-hospital severity-based triage tools and therefore are likely to require a secondary inter-hospital transfer if transported to a non-thrombectomy center. Given the potential for milder severity to represent better underlying cerebrovascular collateral circulation, it is unknown whether transfer delays are still associated with poorer post-stroke outcomes in this patient group.

AIMS

We primarily aimed to examine whether the harmful effect of inter-hospital transfer delay for thrombectomy was different for LVO patients with mild or severe deficits. Secondarily, we also investigated whether imaging markers of collateral circulation were different between severity groups.

METHODS

Registry data from two large Australian thrombectomy centers were used to identify all directly presenting and secondarily transferred LVO patients undergoing thrombectomy, divided into those with lower (NIHSS < 10) and higher (NIHSS ⩾ 10) baseline deficits. The primary outcome was the functional independence or return to baseline defined as modified Rankin Scale 0-2 or baseline at 90 days. Patients with complete baseline CT-perfusion data were analyzed for imaging markers of collateral circulation by baseline severity group.

RESULTS

A total of 1210 LVO patients undergoing thrombectomy were included, of which 273 (22.6%) had lower baseline severity. Despite similar thrombolysis and recanalization rates, transferred patients had lower odds of achieving the primary outcome compared to the primary presentation to a thrombectomy center, where baseline severity was higher (adjusted odds ratio (aOR) 0.759 (95% CI 0.576-0.999)), but not when severity was lower (aOR 1.357 (95% CI 0.764-2.409), p-interaction = 0.122). In the imaging analysis of 436 patients, those with milder severity showed smaller median ischemic core volumes (12.6 (IQR 0.0-17.9) vs 27.5 (IQR 6.5-37.1) mL, p < 0.001)), higher median perfusion mismatch ratio (10.8 (IQR 4.8-54.5) vs 6.6 (IQR 3.5-16.5), p < 0.001), and lower median hypoperfusion intensity ratio (0.25 (IQR 0.18-0.38) vs 0.40 (IQR 0.22-0.57), p < 0.001).

DISCUSSION

Patients receiving secondary inter-hospital transfer for thrombectomy had poorer outcomes compared to those presenting directly to a thrombectomy center if baseline deficits were severe, but this difference was not observed when baseline deficits were milder. This result may potentially be due to our secondary findings of significantly improved collateral circulation markers in lower-severity LVO patients. As such, failure of pre-hospital screening tools to detect lower-severity LVO patients for pre-hospital bypass to a thrombectomy center may not necessarily deleteriously affect outcome.

DATA ACCESS STATEMENT

Anonymized data not published within this article will be made available on request from any qualified investigator.

Early REperfusion Therapy with Intravenous Alteplase for Recovery of VISION in Acute Central Retinal Artery Occlusion (REVISION): Study Protocol of a Phase III Trial

RATIONALE

Meta-analyses of case series of non-arteritic central retinal artery occlusion (CRAO) indicate beneficial effects of intravenous thrombolysis when initiated early after symptom onset. Randomized data is lacking to address this question.

AIMS

REVISION investigates intravenous alteplase within 4.5 hours of monocular vision loss due to acute CRAO.

METHODS

Randomized (1:1), double-blind, placebo-controlled, multicenter adaptive phase III trial.

STUDY OUTCOMES

Primary outcome is functional recovery to normal or mildly impaired vision in the affected eye defined as best corrected visual acuity of the Logarithm of the Minimum An-gle of Resolution of 0.5 or less at 30 days (intention-to-treat analysis). Secondary efficacy out-comes include modified Rankin Score at 90 days and quality of life. Safety outcomes include symptomatic intracranial hemorrhage, major bleeding (International Society on Thrombosis and Haemostasis definition) and mortality. Exploratory analyses of optical coherence tomogra-phy/angiography, ultrasound and MRI biomarkers will be conducted.

SAMPLE SIZE

Using an adaptive design with interim analysis at 120 patients, up to 422 participants (211 per arm) would be needed for 80% power (one-sided alpha 0.025) to detect a difference of 15%, assuming functional recovery rates of 10% in the placebo arm and 25% in the alteplase arm.

DISCUSSION

By enrolling patients within 4.5 hours of CRAO onset, REVISION uses insights from meta-analyses of CRAO case series and randomized thrombolysis trials in acute ischemic stroke. Increased rates of early reperfusion and good neurological outcomes in stroke may trans-late to CRAO with its similar pathophysiology.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04965038; EU Trial Number: 2023-507388-21-00.

Editor's Choice - Comparison of Open Surgery and Endovascular Techniques for Juxtarenal and Complex Neck Aortic Aneurysms: The UK COMPlex AneurySm Study (UK-COMPASS) - Peri-operative and Midterm Outcomes

OBJECTIVE

Treatment of juxtarenal and complex neck abdominal aortic aneurysms (AAAs) is now commonly by endovascular rather than open surgical repair (OSR). Published comparisons show poor validity and scientific precision. UK-COMPASS is a comparative cohort study of endovascular treatments vs. OSR for patients with an AAA unsuitable for standard on label endovascular aneurysm repair (EVAR).

METHODS

All procedures for AAA in England (November 2017 to October 2019) were identified, AAA anatomy assessed in a Corelab, peri-operative risk scores determined, and propensity scoring used to identify patients suitable for either endovascular treatment or OSR. Patients were stratified by aneurysm neck length (0 - 4 mm, 5 - 9 mm, or ≥ 10 mm) and operative risk; the highest quartile was considered high risk and the remainder standard risk. Death was the primary outcome measure. Endovascular treatments included fenestrated EVAR (FEVAR) and off label standard EVAR (± adjuncts).

RESULTS

Among 8 994 patients, 2 757 had AAAs that were juxtarenal, short neck, or complex neck in morphology. Propensity score stratification and adjustment method comparisons included 1 916 patients. Widespread off label use of standard EVAR devices was noted (35.6% of patients). The adjusted peri-operative mortality rate was 2.9%, lower for EVAR (1.2%; p = .001) and FEVAR (2.2%; p = .001) than OSR (4.5%). In standard risk patients with a 0 - 4 mm neck, the mortality rate was 7.4% following OSR and 2.3% following FEVAR. Differences were smaller for patients with a neck length ≥ 5 mm: 2.1% OSR vs. 1.0% FEVAR. At 3.5 years of follow up, the overall mortality rate was 20.7% in the whole study population, higher following FEVAR (27.6%) and EVAR (25.2%) than after OSR (14.2%). However, in the 0 - 4 mm neck subgroup, overall survival remained equivalent. The aneurysm related mortality rate was equivalent between treatments, but re-intervention was more common after EVAR and FEVAR than OSR.

CONCLUSION

FEVAR proves notably safer than OSR in the peri-operative period for juxtarenal aneurysms (0 - 4 mm neck length), with comparable midterm survival. For patients with short neck (5 - 9 mm) and complex neck (≥ 10 mm) AAAs, overall survival was worse in endovascularly treated patients compared with OSR despite relative peri-operative safety. This warrants further research and a re-appraisal of the current clinical application of endovascular strategies, particularly in patients with poor general survival outlook owing to comorbidity and age.

Clinical relevance of intracranial hemorrhage after thrombectomy versus medical management for large core infarct: a secondary analysis of the SELECT2 randomized trial

BACKGROUND

The incidence of intracerebral hemorrhage (ICH) and its effect on the outcomes after endovascular thrombectomy (EVT) for patients with large core infarcts have not been well-characterized.

METHODS

SELECT2 trial follow-up imaging was evaluated using the Heidelberg Bleeding Classification (HBC) to define hemorrhage grade. The association of ICH with clinical outcomes and treatment effect was examined.

RESULTS

Of 351 included patients, 194 (55%) and 189 (54%) demonstrated intracranial and intracerebral hemorrhage, respectively, with a higher incidence in EVT (134 (75%) and 130 (73%)) versus medical management (MM) (60 (35%) and 59 (34%), both P<0.001). Hemorrhagic infarction type 1 (HBC=1a) and type 2 (HBC=1b) accounted for 93% of all hemorrhages. Parenchymal hematoma (PH) type 1 (HBC=1c) and type 2 (HBC=2) were observed in 1 (0.6%) EVT-treated and 4 (2.2%) MM patients. Symptomatic ICH (sICH) (SITS-MOST definition) was seen in 0.6% EVT patients and 1.2% MM patients. No trend for ICH with core volumes (P=0.10) or Alberta Stroke Program Early CT Score (ASPECTS) (P=0.74) was observed. Among EVT patients, the presence of any ICH did not worsen clinical outcome (modified Rankin Scale (mRS) at 90 days: 4 (3-6) vs 4 (3-6); adjusted generalized OR 1.00, 95% CI 0.68 to 1.47, P>0.99) or modify EVT treatment effect (Pinteraction=0.77).

CONCLUSIONS

ICH was present in 75% of the EVT population, but PH or sICH were infrequent. The presence of any ICH did not worsen functional outcomes or modify EVT treatment effect at 90-day follow-up. The high rate of hemorrhages overall still represents an opportunity for adjunctive therapies in EVT patients with a large ischemic core.

Reporting and analysis of process-of-care time measures in clinical trials for hyperacute stroke interventions: a scoping review protocol

OBJECTIVE

The objective of this scoping review is to investigate the reporting and comparison of process-of-care time measures in hyperacute stroke trials and systematic reviews of trials (subsequently referred to as "studies").

INTRODUCTION

Stroke is a leading cause of death and disability worldwide. A crucial factor in determining the effectiveness of stroke care in improving patient outcomes is time; therefore, time measures are frequently reported in studies of hyperacute stroke interventions. However, there is inconsistency in how these measures are reported and compared. Furthermore, there is a lack of clarity in how compatible the reporting methods are with the statistical analysis methods.

INCLUSION CRITERIA

This scoping review will include studies that report and/or compare time measures between key events of interest in the delivery of hyperacute stroke care. Studies of thrombolytic therapy and/or thrombectomy, as well as controlled trials of mobile stroke unit interventions, will be included.

METHODS

The scoping review will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and the JBI methodology for scoping reviews. The search will be executed in MEDLINE (PubMed), Embase (Ovid), and clinical trial registries ANZCTR, ISRCTN, and ClinicalTrials.gov. Title and abstract screening will be followed by full-text screening and subsequent data extraction from eligible studies. The results from this scoping review will be presented in tables and narratively summarized.

REVIEW REGISTRATION

Open Science Framework https://osf.io/y98wz.

Costs and health effects of CT perfusion-based selection for endovascular thrombectomy within 6 hours of stroke onset: a model-based health economic evaluation

BACKGROUND

Although CT perfusion (CTP) is often incorporated in acute stroke workflows, it remains largely unclear what the associated costs and health implications are in the long run of CTP-based patient selection for endovascular treatment (EVT) in patients presenting within 6 hours after symptom onset with a large vessel occlusion.

METHODS

Patients with a large vessel occlusion were included from a Dutch nationwide cohort (n=703) if CTP imaging was performed before EVT within 6 hours after stroke onset. Simulated cost and health effects during 5 and 10 years follow-up were compared between CTP based patient selection for EVT and providing EVT to all patients. Outcome measures were the net monetary benefit at a willingness-to-pay of €80 000 per quality-adjusted life year, incremental cost-effectiveness ratio), difference in costs from a healthcare payer perspective (ΔCosts) and quality-adjusted life years (ΔQALY) per 1000 patients for 1000 model iterations as outcomes.

RESULTS

Compared with treating all patients, CTP-based selection for EVT at the optimised ischaemic core volume (ICV≥110 mL) or core-penumbra mismatch ratio (MMR≤1.4) thresholds resulted in losses of health (median ΔQALYs for ICV≥110 mL: -3.3 (IQR: -5.9 to -1.1), for MMR≤1.4: 0.0 (IQR: -1.3 to 0.0)) with median ΔCosts for ICV≥110 mL of -€348 966 (IQR: -€712 406 to -€51 158) and for MMR≤1.4 of €266 513 (IQR: €229 403 to €380 110)) per 1000 patients. Sensitivity analyses did not yield any scenarios for CTP-based selection of patients for EVT that were cost-effective for improving health, including patients aged ≥80 years CONCLUSION: In EVT-eligible patients presenting within 6 hours after symptom onset, excluding patients based on CTP parameters was not cost-effective and could potentially harm patients.

JNZNBRK: Physical Experiments in Light, Modulation, and Substrate

We requested an interview with the Winnipeg-based JNZNBRK art collaborative upon being curious about their work process. The artwork they present on jnznbrk.com suggested a thoughtful aesthetic involving compelling physical exhibits. As we are always interested in the physicalization of data, we were keen to hear about possible considerations that might contribute as relevant to our, and our readers', practices.

The surgical care of diabetic feet: a survey about clinics, acute care, and the surgical specialists involved

INTRODUCTION

Diabetic foot problems are becoming increasingly common. Diabetic foot care services are fundamental in managing them, and there is the further issue of acute surgery for foot sepsis. The involvement of different surgical specialists has been variable; this survey aimed to provide information about current service provision.

METHODS

Questionnaires were emailed to Vascular Society members, and targeted approaches were then undertaken.

RESULTS

We aimed to obtain information from 61 localities identified as providing shared services, and received informative responses from 46 (75%). These described diabetic foot clinics each day (11%), or once (50%), twice (13%) or three times (17%) weekly - attended regularly by vascular surgeons, and less frequently by orthopaedic surgeons. The frequency of clinics was considered inadequate by 30% of respondents, and only 75% reported written policies for diabetic foot care pathways. Operations for acute foot sepsis are done by vascular surgeons in 98% of localities and by orthopaedic surgeons in 22% (in some localities by both): the latter are orthopaedic foot specialists in all localities but two. Both specialties perform a range of foot procedures, including toe/foot-preserving operations. Major amputations are done by vascular surgeons in 98% of localities and by orthopaedic surgeons in only 9%. All deformity correction procedures are performed by orthopaedic surgeons.

CONCLUSION

This survey shows that diabetic foot clinics are now held frequently in most localities. There is variation in the involvement of vascular and orthopaedic surgeons. Some localities need to consider increased provision of clinics and better defined pathways of care.

Nathan Selikoff: Explorations in Higher Dimensionality and Complexity

While data scientists pursue new extremes of high-dimensional data, and data visualization professionals attempt to visualize within that space, Nathan Selikoff's work suggested a unique perspective on relationship among complexity, higher dimensions, and sensing what otherwise cannot be sensed. His long-tailed pursuit of visualizing complexity piqued our interest as we interviewed him for this article.

Endovascular therapy in acute ischemic stroke with poor reperfusion is associated with worse outcomes compared with best medical management: a HERMES substudy

BACKGROUND

Functional outcomes in patients with acute ischemic stroke (AIS) with large vessel occlusion (LVO) undergoing endovascular treatment (EVT) with poor reperfusion were compared with patients with AIS-LVO treated with best medical management only.

METHODS

Data are from the HERMES collaboration, a patient-level meta-analysis of seven randomized EVT trials. Baseline characteristics and functional outcomes (modified Rankin Scale (mRS) score at 90 days) were compared between patients with poor reperfusion (defined as modified Thrombolysis in Cerebral Infarction Score 0-1 on the final intracranial angiography run as assessed by the central imaging core laboratory) and patients in the control arm with multivariable logistic ordinal logistic regression adjusted for pre-specified baseline variables.

RESULTS

972 of 1764 patients from the HERMES collaboration were included in the analysis: 893 in the control arm and 79 in the EVT arm with final mTICI 0-1. Patients with poor reperfusion who underwent EVT had higher baseline National Institutes of Health Stroke Scale than controls (median 19 (IQR 15.5-21) vs 17 (13-21), P=0.011). They also had worse mRS at 90 days compared with those in the control arm in adjusted analysis (median 4 (IQR 3-6) vs median 4 (IQR 2-5), adjusted common OR 0.59 (95% CI 0.38 to 0.91)). Symptomatic intracranial hemorrhage was not different between the two groups (3.9% vs 3.5%, P=0.75, adjusted OR 0.94 (95% CI 0.23 to 3.88)).

CONCLUSION

Poor reperfusion after EVT was associated with worse outcomes than best medical management, although no difference in symptomatic intracranial hemorrhage was seen. These results emphasize the need for additional efforts to further improve technical EVT success rates.

Power Analysis for Ordinal Analyses of the Modified Rankin Scale and an Online and Downloadable Tool for Practical Use

BACKGROUND

Several methods for conducting power analysis of studies with outcomes across the full ordinal modified Rankin Scale are proposed in the literature. No systematic comparison of accuracy, agreement, and sensitivity to small changes in hypothesized effect sizes for these methods is available. Our aim is to conduct such a systematic comparative analysis and to introduce a comprehensive freely available online tool to facilitate appropriate power analyses for ordinal outcomes.

METHODS

We performed simulation studies utilizing the control arm modified Rankin Scale distributions from the AVERT (A Very Early Rehabilitation Trial), EXTEND (Extending the Time for Thrombolysis in Emergency Neurological Deficits), and HERMES (Highly Effective Reperfusion Evaluated in Multiple Endovascular Stroke Trials) studies, as well as a uniform distribution, in combination with hypothetical treatment effects. We systematically evaluated published power formulas for Ordinal Logistic Regression and Tournament Methods (generalized odds ratio; Win Probability; Win Ratio; and Wilcoxon-Mann-Whitney U test). We also developed an online and downloadable Shiny R app facilitating sample size calculation for, and ordinal analysis of, modified Rankin Scale data.

RESULTS

Power formulas for Tournament Methods performed well, while the formula for ordinal logistic regression was inaccurate. Tang's Wilcoxon-Mann-Whitney U test sample size formula exhibited the highest accuracy. All methods, including ordinal logistic regression, had almost identical empirical power for a given sample size. All power methods exhibited sensitivity to small changes in hypothesized effect size. The developed freely available online app supports analytical and visualization requirements for all investigated methods for power and statistical analyses of ordinal modified Rankin Scale outcomes.

CONCLUSIONS

As Tournament Method sample size formulas are assumption-free and accurately calculate power, stroke researchers should use these methods when designing studies with outcomes measured on the full or partially collapsed modified Rankin Scale as well as other ordinal scales, even if they intend to use ordinal logistic regression for analysis. Conducting sensitivity analyses of the effect size assumptions are essential for appropriate sample size estimation. Our developed tool supports both of these recommendations (https://www.thembc.com.au/tournamentmethods).

Prediction of delayed reperfusion in patients with incomplete reperfusion following thrombectomy

BACKGROUND

The clinical course of patients with incomplete reperfusion after thrombectomy, defined as an expanded Thrombolysis in Cerebral Infarction (eTICI) score of 2a-2c, is heterogeneous. Patients showing delayed reperfusion (DR) have good clinical outcomes, almost comparable to patients with ad-hoc TICI3 reperfusion. We aimed to develop and internally validate a model that predicts DR occurrence in order to inform physicians about the likelihood of a benign natural disease progression.

PATIENTS AND METHODS

Single-center registry analysis including all consecutive, study-eligible patients admitted between 02/2015 and 12/2021. Preliminary variable selection for the prediction of DR was performed using bootstrapped stepwise backward logistic regression. Interval validation was performed with bootstrapping and the final model was developed using a random forests classification algorithm. Model performance metrics are reported with discrimination, calibration, and clinical decision curves. Primary outcome was concordance statistics as a measure of goodness of fit for the occurrence of DR.

RESULTS

A total of 477 patients (48.8% female, mean age 74 years) were included, of whom 279 (58.5%) showed DR on 24 follow-up. The model's discriminative ability for predicting DR was adequate (C-statistics 0.79 [95% CI: 0.72-0.85]). Variables with strongest association with DR were: atrial fibrillation (aOR 2.06 [95% CI: 1.23-3.49]), Intervention-To-Follow-Up time (aOR 1.06 [95% CI: 1.03-1.10]), eTICI score (aOR 3.49 [95% CI: 2.64-4.73]), and collateral status (aOR 1.33 [95% CI: 1.06-1.68]). At a risk threshold of R = 30%, use of the prediction model could potentially reduce the number of additional attempts in one out of four patients who will have spontaneous DR, without missing any patients who do not show spontaneous DR on follow-up.

CONCLUSIONS

The model presented here shows fair predictive accuracy for estimating chances of DR after incomplete thrombectomy. This may inform treating physicians on the chances of a favorable natural disease progression if no further reperfusion attempts are made.

Changing Aesthetics in Biomolecular Graphics

Aesthetics for the visualization of biomolecular structures have evolved over the years according to technological advances, user needs, and modes of dissemination. In this article, we explore the goals, challenges, and solutions that have shaped the current landscape of biomolecular imagery from the overlapping perspectives of computer science, structural biology, and biomedical illustration. We discuss changing approaches to rendering, color, human-computer interface, and narrative in the development and presentation of biomolecular graphics. With this historical perspective on the evolving styles and trends in each of these areas, we identify opportunities and challenges for future aesthetics in biomolecular graphics that encourage continued collaboration from multiple intersecting fields.

Infarcts in a New Territory: Insights From the ESCAPE-NA1 Trial

BACKGROUND

Infarct in a new territory (INT) is a known complication of endovascular stroke therapy. We assessed the incidence of INT, outcomes after INT, and the impact of concurrent treatments with intravenous thrombolysis and nerinetide.

METHODS

Data are from ESCAPE-NA1 trial (Safety and Efficacy of Nerinetide [NA-1] in Subjects Undergoing Endovascular Thrombectomy for Stroke), a multicenter, international randomized study that assessed the efficacy of intravenous nerinetide in subjects with acute ischemic stroke who underwent endovascular thrombectomy within 12 hours from onset. Concurrent treatment and outcomes were collected as part of the trial protocol. INTs were identified on core lab imaging review of follow-up brain imaging and defined by the presence of infarct in a new vascular territory, outside the baseline target occlusion(s) on follow-up brain imaging (computed tomography or magnetic resonance imaging). INTs were classified by maximum diameter (<2, 2-20, and >20 mm), number, and location. The association between INT and clinical outcomes (modified Rankin Scale and death) was assessed using standard descriptive techniques and adjusted estimates of effect were derived from Poisson regression models.

RESULTS

Among 1092 patients, 103 had INT (9.3%, median age 69.5 years, 49.5% females). There were no differences in baseline characteristics between those with versus without INT. Most INTs (91/103, 88.3%) were not associated with visible occlusions on angiography and 39 out of 103 (37.8%) were >20 mm in maximal diameter. The most common INT territory was the anterior cerebral artery (27.8%). Almost half of the INTs were multiple (46 subjects, 43.5%, range, 2-12). INT was associated with poorer outcomes as compared to no INT on the primary outcome of modified Rankin Scale score of 0 to 2 at 90 days (adjusted risk ratio, 0.71 [95% CI, 0.57-0.89]). Infarct volume in those with INT was greater by a median of 21 cc compared with those without, and there was a greater risk of death as compared to patients with no INT(adjusted risk ratio, 2.15 [95% CI, 1.48-3.13]).

CONCLUSIONS

Infarcts in a new territory are common in individuals undergoing endovascular thrombectomy for acute ischemic stroke and are associated with poorer outcomes. Optimal therapeutic approaches, including technical strategies, to reduce INT represent a new target for incremental quality improvement of endovascular thrombectomy.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02930018.

Mechanical Thrombectomy Global Access For Stroke (MT-GLASS): A Mission Thrombectomy (MT-2020 Plus) Study

BACKGROUND

Despite the well-established potent benefit of mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke, access to MT has not been studied globally. We conducted a worldwide survey of countries on 6 continents to define MT access (MTA), the disparities in MTA, and its determinants on a global scale.

METHODS

Our survey was conducted in 75 countries through the Mission Thrombectomy 2020+ global network between November 22, 2020, and February 28, 2021. The primary end points were the current annual MTA, MT operator availability, and MT center availability. MTA was defined as the estimated proportion of patients with LVO receiving MT in a given region annually. The availability metrics were defined as ([current MT operators×50/current annual number of estimated thrombectomy-eligible LVOs]×100 = MT operator availability) and ([current MT centers×150/current annual number of estimated thrombectomy-eligible LVOs]×100= MT center availability). The metrics used optimal MT volume per operator as 50 and an optimal MT volume per center as 150. Multivariable-adjusted generalized linear models were used to evaluate factors associated with MTA.

RESULTS

We received 887 responses from 67 countries. The median global MTA was 2.79% (interquartile range, 0.70-11.74). MTA was <1.0% for 18 (27%) countries and 0 for 7 (10%) countries. There was a 460-fold disparity between the highest and lowest nonzero MTA regions and low-income countries had 88% lower MTA compared with high-income countries. The global MT operator availability was 16.5% of optimal and the MT center availability was 20.8% of optimal. On multivariable regression, country income level (low or lower-middle versus high: odds ratio, 0.08 [95% CI, 0.04-0.12]), MT operator availability (odds ratio, 3.35 [95% CI, 2.07-5.42]), MT center availability (odds ratio, 2.86 [95% CI, 1.84-4.48]), and presence of prehospital acute stroke bypass protocol (odds ratio, 4.00 [95% CI, 1.70-9.42]) were significantly associated with increased odds of MTA.

CONCLUSIONS

Access to MT on a global level is extremely low, with enormous disparities between countries by income level. The significant determinants of MT access are the country's per capita gross national income, prehospital LVO triage policy, and MT operator and center availability.

Risk factors of unexplained early neurological deterioration after treatment for ischemic stroke due to large vessel occlusion: a post hoc analysis of the HERMES study

BACKGROUND

Early neurological deterioration (END) after endovascular treatment (EVT) in patients with anterior circulation acute ischemic stroke (AIS) is associated with poor outcome. END may remain unexplained by parenchymal hemorrhage (UnEND). We aim to analyze the risk factors of UnEND in the medical management (MM) and EVT arms of the HERMES study.

METHODS

We conducted a post-hoc analysis of anterior AIS patients who underwent EVT for proximal anterior occlusions. Risk factors of UnEND, defined as a worsening of ≥4 points between baseline National Institutes of Health Stroke Scale (NIHSS) and NIHSS at 24 hours without hemorrhage, were compared between both arms using mixed logistic regression models adjusted for baseline characteristics. An interaction analysis between the EVT and MM arms for risk factors of UnEND was conducted.

RESULTS

Among 1723 patients assessable for UnEND, 160 patients experienced an UnEND (9.3%), including 9.1% (78/854) in the EVT arm and 9.4% (82/869) in the MM arm. There was no significant difference in the incidence of UnEND between the two study arms. In the EVT population, independent risk factors of UnEND were lower baseline NIHSS, higher baseline glucose, and lower collateral grade. In the MM population, the only independent predictor of UnEND was higher baseline glucose. However, we did not demonstrate an interaction between EVT and MM for baseline factors as risk factors of UnEND. UnEND was, similarly in both treatment groups, a significant predictor of unfavorable outcome in both the EVT (p<0.001) and MM (p<0.001) arms.

CONCLUSIONS

UnEND is not an uncommon event, with a similar rate which ever treatment arm is considered. In the clinical scenario of AIS due to large vessel occlusion, no patient-related factor seems to increase the risk for UnEND when treated by EVT compared with MM.

Generalised pairwise comparisons for trend: An extension to the win ratio and win odds for dose-response and prognostic variable analysis with arbitrary statements of outcome preference

The win ratio is a novel approach for handling complex patient outcomes that have seen considerable interest in the medical statistics literature, and operates by considering all-to-all pairwise statements of preference on outcomes. Recent extensions to the method have focused on the two-group case, with few developments made for considering the impact of a well-ordered explanatory variable, which would allow for dose-response analysis or the analysis of links between complex patient outcomes and prognostic variables. Where such methods have been developed, they are semiparametric methods that can only be applied to survival outcomes. In this article, we introduce the generalised pairwise comparison for trend, a modified form of Agresti's generalised odds ratio. This approach is capable of considering arbitrary statements of preference, thus enabling its use across all types of outcome data. We provide a simulation study validating the approach and illustrate it with three clinical applications in stroke research.

The second randomized controlled ENhanced Control of Hypertension ANd Thrombectomy strokE stuDy (ENCHANTED2): Protocol and progress

BACKGROUND

Uncertainty exists over the optimal level of blood pressure (BP) after mechanical thrombectomy (MT) for acute ischemic stroke (AIS).

OBJECTIVES

We aim to determine the effectiveness and safety of intensive BP-lowering following MT reperfusion of large-vessel occlusion (LVO)-related AIS.

DESIGN

The second ENhanced Control of Hypertension ANd Thrombolysis strokE stuDy (ENCHANTED2) is an investigator-initiated, multicenter, prospective, randomized, open, blinded-endpoint (PROBE) trial of intensive systolic BP (SBP) control in reperfused (extended treatment in cerebral infarction (eTICI) classification 2b/2c/3) LVO-AIS patients with persistent hypertension (SBP ⩾ 140 mmHg) at 60+ sites in China, and Australia and the United Kingdom. Eligible patients are centrally randomly allocated to more- (target SBP ⩽ 120 mmHg within 1 h) or less-intensive (target SBP 140-180 mmHg) BP management, to be maintained for 72 h. Primary outcome is an ordinal shift analysis of scores on the modified Rankin scale (mRS) at 90 days. Sample size of 2257 patients provides 90% power to detect a 6.5% absolute reduction in poor outcome from more-intensive BP-lowering using ordinal logistic regression.

PROGRESS

Recruitment started in China in July 2020. At a meeting of the independent Data and Safety Monitoring Board in March 2022 to review primary outcome data available for 347 patients, they recommended suspension of recruitment due to safety concerns in the more-intensive group; which was implemented by the Trial Steering Committee (TSC) with 817 randomized patients only in China. The TSC then stopped recruitment after the safety concerns persisted on further review of the data in June 2022. The TSC will make a decision on restarting the trial with modification of the protocol when the results are made public.

DISCUSSION

ENCHANTED2 will provide further randomized evidence on the role of intensive BP-lowering after reperfusion in MT-treated AIS patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04140110; registered 25 October 2019.

Abstract WMP91: The Penumbra Salvage Index (PSI) As A Novel Measure Of Successful Reperfusion

Objective: We propose a novel measure, the PSI, to evaluate procedural success and prognostication after EVT and compare its prognostic ability with successful reperfusion (mTICI ≥2b).

Methods: SELECT EVT patients with adequate follow-up MR DWI imaging were stratified based on PSI [ratio of salvaged tissue volume (Tmax >6s volume at baseline – f/up DWI infarct volume) to the Tmax >6s volume at baseline] into good (PSI≥50%) and poor penumbral salvage (PSI<50%). Multivariable regression models examined the association of PSI with functional outcomes as well as predictors of PSI. ROC curve analysis evaluated the predictive ability of PSI and compared it with mTICI≥2b.

Results: 142/206(69%) had good penumbral salvage, with better CT ASPECTS (Good PSI: 9(7-10) vs Poor PSI: 7(6-9),p<0.001), baseline core infarct (Good PSI: 5.9(0.0-20.0)ml vs Poor PSI: 19.4(3.4-46.3)ml, p<0.001) and mTICI≥2b (Good PSI:91% vs Poor PSI: 64%, p<0.001). Good PSI was independently associated with higher odds of mRS 0-2 (Good PSI: 69% vs Poor PSI: 26%, aOR:5.89, 95%CI:2.25-15.45, p<0.001) and mRS 0-1 (Good PSI: 56% vs Poor PSI: 16%, aOR: 4.98, 95%CI:1.86-13.31, p=0.001). Predictors of a good PSI included a lower presenting NIHSS (aOR: 0.93, 95%CI: 0.87-0.99, p=0.026), smaller ischemic core (aOR: 0.96, 95%CI: 0.95-0.98, p<0.001) larger Tmax>6s volume (aOR: 1.01, 95%CI: 1.00-1.02, p=0.003) and mTICI≥2b (aOR: 8.84, 95%CI: 3.16-24.71, p<0.001). PSI demonstrated better AUC values (0.811) as compared to mTICI≥2b (0.786) in the ROC analysis.

Conclusion: Good penumbral salvage is associated with higher odds of functional independence, and has a better predictive value than successful reperfusion on cerebral angiogram after EVT. Prospective studies are needed to confirm the predictive utility of the PSI.

Abstract WP56: Improvement In Motor And Language Domains Mediates Most Of The Effect Of 24h NIHSS Improvement On Functional Independence

Introduction: Improvement in NIH stroke scale scores on 24h follow-up is considered a key prognostic element after endovascular thrombectomy (EVT). We aimed to evaluate the proportion of effect of 24h NIHSS improvement on mRS 0-2 at 90d mediated through improvement in motor and language domains.

Methods: From SELECT study, EVT patients with detailed NIHSS components on presentation and 24h follow-up as well as complete mRS on discharge and 90d were selected. Motor improvement was defined as ≥2 point in cumulative arms and legs score or 0 score at 24h and language improvement was defined as ≥1 point in cumulative aphasia and dysarthria scores at 24h. Mediation analysis framework using 4-step method (Figure 1a) was used to evaluate the effect of 24h NIHSS improvement mediated through improvement in motor and language scores.

Results: Of 192 eligible EVT patients, 176 demonstrated motor deficits and 187 demonstrated language deficits. 24h NIHSS improvement was significantly associated with mRS 0-2 (aOR:1.15[1.07-1.23], p<0.001) - step 1. 24h NIHSS improvement was also significantly associated with motor (aOR:1.77[1.48-2.12],p<0.001) and speech improvement (aOR:1.25[1.16-1.36],p<0.001) - step 2. In the full model, motor (aOR:3.00[1.07-8.46],p=0.037) and speech improvement (aOR:3.15[1.37-7.27],p=0.007) were significantly associated with mRS 0-2, whereas 24h NIHSS improvement was no longer a significant predictor (aOR:1.05[0.96-1.15],p=0.33) - step 3 of figure 1a. Motor improvement mediated 68% and speech improvement mediated 27% of the association of 24h NIHSS improvement with mRS 0-2 (Figure 1b) - step 4.

Conclusions: Almost all (~95%) of the effect of 24h NIHSS improvement on functional independence (mRS 0-2) was mediated through specific improvement in motor and language domains, suggesting a large role of improvement in motor and language domains in achieving better functional independence. Further studies are needed to confirm the findings.

Abstract 94: Randomized, Double-blind, Placebo-controlled Phase 1 Study Of Vwf-binding Aptamer, Bb-031: Safety, Tolerability, Pharmacokinetic And Pharmacodynamic Activity In Healthy Volunteers

Introduction: Von Willebrand Factor (VWF) is a ubiquitous component of thrombi extracted by endovascular thrombectomy from patients with large vessel occlusion (LVO) stroke. BB-031 is a modified RNA aptamer that targets von Willebrand Factor (VWF) that lyses occlusive thrombi and improves outcomes in pre-clinical models of acute ischemic stroke (AIS).

Hypothesis: BB-031 is safe, tolerable, and inhibits both VWF binding and activity in a dose-dependent manner.

Methods: Healthy participants were randomized to receive BB-031 or placebo (6:2) by intravenous bolus injection at single ascending doses (SAD) of 0.1, 0.3, 1.0, 2.0 and 4.0 mg/kg (total n=40). Serial Clinical assessment, and blood sample collection for pharmacokinetic (PK) and pharmacodynamic (PD) analysis were performed. Non-compartmental PK analysis was conducted using Phoenix WinNonlin. PD evaluation included measurement of VWF inhibition and whole blood thrombosis (Platelet Function Analyzer [PFA-200]).

Results: BB-031 was safe and well-tolerated for 28 days following single IV doses up to 4.0 mg/kg. There were no significant adverse events (SAEs), or treatment-emergent adverse events (TEAEs) leading to dose discontinuation. Minor events included bleeding at an IV site in 1 participant, and minor bleeding of an ulcer on the tongue in 1 participant. None of the minor TEAEs were dose-dependent. BB-031 demonstrated nonlinear, dose-dependent plasma PK across the dose range tested, with an apparent mean terminal half-life (t 1/2 ) of 18 min at 0.1 mg/kg to 67 min at 4.0 mg/kg. Dose-dependent changes in VWF binding were observed; >95% maximal mean change from baseline was reached following a single IV dose of 4.0 mg/kg. Finally, PFA-200 results showed complete inhibition of clot formation (closing time ≥300 seconds) at all doses tested with a dose-dependent duration of inhibition and return to normal range.

Conclusion: This first-in-human SAD study of BB-031 demonstrated safety following a single IV dose of 0.1 to 4 mg/kg, and dose-dependent patterns of VWF binding and platelet function changes. These results lay the foundation for future studies in patients suffering from thrombotic conditions including AIS.

Abstract WP106: Hemispheric Comparison Of Magnetic Susceptibility 24-72 Hours After Reperfusion

Introduction: Magnetic susceptibility is a radiological contrast mechanism that may provide a measure of oxygenation and contribute to an understanding the pathophysiology of stroke. Currently, there are few studies that have explored magnetic susceptibility in ischemic tissue as a marker of tissue injury. Our study assesses day one ischemic tissue post-reperfusion for changes in magnetic susceptibility and evaluates its relationship with radiological markers of ischemic injury - apparent diffusion coefficient (ADC).

Methods: In a prospective observational study, thirty-five ischemic stroke patients who underwent endovascular thrombectomy were scanned with MRI (24 – 72 hours after reperfusion) to obtain multi-echo Gradient Echo and DWI images. An experienced neuroradiologist manually delineated ischemic tissue ROIs (region of interest) on DWI images. Contralateral ROIs were obtained using an automated method. The cerebrospinal fluid and regions of haemorrhagic transformation were excluded from the ROIs. A Morphology Enabled Dipole Inversion (MEDI) pipeline was employed to generate Quantitative Susceptibility Mapping (QSM) images, and these were used to quantify magnetic susceptibility. Mean magnetic susceptibility and mean ADC values were measured in these ROIs, and these values were then correlated.

Results: Mean magnetic susceptibility of the ischemic ROI was significantly higher than that of the contralateral ROI (0.71±11.72 ppb, -5.59±7.30 ppb; p = 0.003). Mean ADC values of the ROI in the ischemic hemisphere were significantly lower than those in the contralateral hemisphere (0.65±0.09 х 10 -3 mm 2 /s, 0.81±0.05 х 10 -3 mm 2 /s; p = 1.31 х 10 -11 ). No significant correlation between susceptibility and ADC was found (ρ = -0.278, p = 0.106).

Conclusion: Magnetic susceptibility in the ischemic tissue is measurable and is elevated when compared to the normal tissue. This may be attributed to the increased oxygen extraction fraction in the ischemic tissue. Further voxel wise analysis and larger longitudinal multi-parametric analysis correlating magnetic susceptibility with other imaging measures of tissue injury over time will help characterise the significance of lesional magnetic susceptibility changes in ischemic tissue.

Abstract TMP54: Increased Thrombectomy Time Saving From Melbourne Mobile Stroke Unit Operation During Covid-19 Pandemic

Introduction: Mobile stroke units (MSU) have demonstrated major time savings for thrombolysis but mixed evidence for endovascular thrombectomy (EVT). COVID-19 precautions have dramatically slowed EVT workflows across Australia and we therefore aimed to examine the effect of the Melbourne MSU on thrombectomy times before and during the current pandemic.

Methods: Patients receiving EVT facilitated by the Melbourne MSU from 2017-2021 were compared to non-MSU patients (metropolitan direct and secondary transfer for EVT) admitted to the largest Melbourne EVT centre. Quantile regression analysis was used to calculate the median time difference (50 th quantile) between MSU and non-MSU patients before and during the pandemic, grouped by patients within an EVT centre ambulance catchment or those outside (who either received inter-hospital transfer or MSU-facilitated bypass to an EVT centre).

Results: A total of 402 patients (112 MSU) were included. Pre-pandemic, no reduction in dispatch to arterial access time was seen for MSU patients within an EVT centre catchment (median 11min slower, p=0.38). However, a significant time saving was observed during the pandemic (median 29 min faster, p<0.001, p-interaction=0.0065). MSU care reduced hospital arrival to arterial access time by median 19min pre-pandemic vs 40 min during the pandemic, p-interaction<0.001). The pandemic did not alter MSU-related time savings for patients located outside of an EVT centre catchment.

Conclusions: Melbourne MSU facilitation of EVT during the COVID-19 pandemic resulted in greater time savings for patients located close to a thrombectomy centre, while substantial time savings were maintained for those needing bypass from the local non-EVT hospital. This suggests that MSU operation enables streamlined EVT workflows during the pandemic by providing early pre-hospital notification and interventional angiography activation.

Abstract WMP47: Low Sensitivity Of Widely Used Emergency Dispatch Algorithm For Thrombectomy Patients - Implications For Mobile Stroke Units

Introduction: Widely used emergency dispatch algorithms such as the Advanced Medical Priority Dispatch System (AMPDS) have limited diagnostic accuracy for prehospital diagnosis of stroke. With advent of mobile stroke units (MSU), this inaccuracy prevents optimal dispatch to patients who may benefit. Expedited endovascular thrombectomy (EVT) is a major contributor to net benefit of MSUs. We assessed the accuracy of AMPDS for recognizing stroke in thrombectomy patients in the Australian state of Victoria.

Methods: We included consecutive patients accepted for EVT (direct and secondary transfer) to The Royal Melbourne Hospital from 2007-2021 in whom linked AMPDS dispatch codes could be obtained from Ambulance Victoria. The primary outcome was the proportion of cases dispatched as stroke vs non-stroke with subgroup analyses of the effect of baseline clinical severity, metropolitan vs rural dispatch and time to thrombectomy. Chi square and Mann Whitney tests were used as appropriate.

Results: A total of n=618 patients were included with baseline NIHSS 16 (IQR 10-20). Of these, only 62% (95% CI 58-66) were initially dispatched as suspected stroke, with the most common non-stroke diagnoses being “Unconscious/Fainting” (19.2%) and “Falls” (6.9%). Those with a higher baseline severity (NIHSS ≥10) were less likely to be classified as stroke than those with lower severity (59% vs 76%, p<0.001), while no difference was found between metropolitan and rural patients (p=0.066). Overall, no significant time differences were found between stroke and non-stroke dispatches for ambulance dispatch to arterial access (median 208 vs 216 min, p=0.593) or hospital arrival to arterial access (median 42 vs 42 min, p=0.851). However, only 32 patients were treated on the MSU, which commenced operation November 2017.

Conclusions: Almost 40% of thrombectomy patients did not receive an initial AMPDS dispatch of suspected stroke and those with higher baseline severity were more likely to be misclassified. Although time to thrombectomy was not significantly different between stroke vs non-stroke dispatches, MSU treatment was under-represented. Our findings have implications for emergency medical services and particularly mobile stroke units which rely on accurate stroke dispatch.

Abstract WMP49: Occult Contrast Retention Post-thrombectomy On 24-hour Follow-up CT: Associations And Impact On Imaging Analysis

Introduction: CT performed 24h post-treatment is widely used to assess radiological outcomes in stroke studies. Even without visible hyperattenuation, occult angiographic contrast may persist in the brain and confound Hounsfield Unit-based imaging metrics such as Net Water Uptake (NWU), a measure of cerebral edema based on tissue hypoattenuation. We aimed to assess (1) the presence of retained contrast post-thrombectomy on 24h CT by comparing NWU measurements with and without adjustment for iodine using dual energy CT (DECT), (2) factors associated with amount of retention, and (3) its impact on the accuracy of NWU.

Methods: In a prospective study of patients with anterior circulation large vessel occlusion who had post-thrombectomy follow-up DECT performed 24h post-treatment from two Comprehensive Stroke Centres (November 2021 to May 2022), NWU was calculated by interside comparison of Hounsfield Units of the infarct lesion and its mirror homolog. Retained contrast was quantified by the difference in NWU values with and without adjustment for iodine. We tested correlation between NWU and tissue swelling using relative hemispheric volume (rHV) and midline shift (MLS). Patients with visible hyperdensities from hemorrhagic transformation or visible contrast retention, and bilateral infarcts were excluded.

Results: Of 125 patients analysed (median age 71 [IQR 61-80], baseline NIHSS 16 [IQR 9.75-21]), reperfusion (eTICI 2b-3) was achieved in 120 patients (96.8%). NWU measured with iodine adjustment was significantly higher than NWU measured without adjustment (17.1% vs 10.8%, p<0.001). In multivariable median regression analysis, age (p=0.031), number of passes (p<0.001) and having CT perfusion at baseline (p=0.008) were independently associated with amount of retained contrast. NWU measured with iodine adjustment correlated with rHV (p=0.043) and MLS (p=0.033), but NWU without adjustment did not (rHV p=0.350; MLS p=0.347).

Conclusion: Occult angiographic iodine contrast significantly affects NWU on CT at 24h. Our data suggest adjustment for retained iodine using DECT is required for accurate NWU measures post-thrombectomy. Future studies analysing CT post-thrombectomy should consider the significance of occult contrast retention.

Abstract 92: Tenecteplase Treatment And Thrombus Characteristics Associated With Early Reperfusion - An EXTEND-IA TNK Trials Analysis

Background: Intracranial occlusion site, contrast permeability, and clot burden are thrombus characteristics that influence alteplase-associated reperfusion. In this study, we assessed the reperfusion efficacy of tenecteplase and alteplase in subgroups based on these characteristics in a pooled analysis of the EXTEND-IA TNK trials.

Methods: Patients with large vessel occlusion (LVO) were randomized to treatment with tenecteplase (0.25mg/kg or 0.4mg/kg) or alteplase (0.9mg/kg) prior to thrombectomy. The primary outcome, early reperfusion, was defined as the absence of retrievable thrombus or >50% reperfusion on initial angiographic assessment. We compared the treatment effect of tenecteplase versus alteplase overall, and in subgroups based on intracranial occlusion site, the presence of contrast permeability (measured via residual flow grades), and clot burden (measured via clot burden scores), whilst adjusting for relevant covariates using mixed effects logistic regression models.

Results: Among the 465 patients in the primary analysis, early reperfusion occurred in 18% (84/465). Tenecteplase was associated with a higher odds of early reperfusion (tenecteplase: 75/369 [20%] vs. alteplase: 9/96 [9%], aOR: 2.18 [95%CI: 1.03-4.63]). The difference between thrombolytics was most notable in distal M1 or M2 occlusions (tenecteplase: 53/176 [30%] vs. alteplase: 4/42 [10%], aOR: 3.73 [95%CI: 1.25-11.11]), thrombi with contrast permeability (tenecteplase: 38/160 [24%] vs. alteplase: 5/48 [10%], aOR: 2.83 [95%CI: 1.00-8.05]), and in low clot burden occlusions (tenecteplase: 66/261 [25%] vs. alteplase: 5/67 [7%], aOR: 3.93 [95%CI: 1.50-10.33]). Both thrombolytics had limited early reperfusion efficacy in proximal occlusions (ICA: tenecteplase 1/73 [1%] vs. alteplase 1/19 [5%]) and in high clot burden occlusions (tenecteplase: 9/108 [8%] vs. alteplase: 4/29 [14%], aOR: 0.58 [95%CI: 0.16-2.06]).

Conclusions: Tenecteplase demonstrates superior early reperfusion versus alteplase in distal LVO, in contrast-permeable thrombi, and in lesions with low clot burden. Reperfusion efficacy remains limited in ICA occlusions and lesions with high clot burden. Further improvements in intravenous thrombolytics are required.

Intensive blood pressure control after endovascular thrombectomy for acute ischaemic stroke (ENCHANTED2/MT): a multicentre, open-label, blinded-endpoint, randomised controlled trial

BACKGROUND

The optimum systolic blood pressure after endovascular thrombectomy for acute ischaemic stroke is uncertain. We aimed to compare the safety and efficacy of blood pressure lowering treatment according to more intensive versus less intensive treatment targets in patients with elevated blood pressure after reperfusion with endovascular treatment.

METHODS

We conducted an open-label, blinded-endpoint, randomised controlled trial at 44 tertiary-level hospitals in China. Eligible patients (aged ≥18 years) had persistently elevated systolic blood pressure (≥140 mm Hg for &gt;10 min) following successful reperfusion with endovascular thrombectomy for acute ischaemic stroke from any intracranial large-vessel occlusion. Patients were randomly assigned (1:1, by a central, web-based program with a minimisation algorithm) to more intensive treatment (systolic blood pressure target &lt;120 mm Hg) or less intensive treatment (target 140-180 mm Hg) to be achieved within 1 h and sustained for 72 h. The primary efficacy outcome was functional recovery, assessed according to the distribution in scores on the modified Rankin scale (range 0 [no symptoms] to 6 [death]) at 90 days. Analyses were done according to the modified intention-to-treat principle. Efficacy analyses were performed with proportional odds logistic regression with adjustment for treatment allocation as a fixed effect, site as a random effect, and baseline prognostic factors, and included all randomly assigned patients who provided consent and had available data for the primary outcome. The safety analysis included all randomly assigned patients. The treatment effects were expressed as odds ratios (ORs). This trial is registered at ClinicalTrials.gov, NCT04140110, and the Chinese Clinical Trial Registry, 1900027785; recruitment has stopped at all participating centres.

FINDINGS

Between July 20, 2020, and March 7, 2022, 821 patients were randomly assigned. The trial was stopped after review of the outcome data on June 22, 2022, due to persistent efficacy and safety concerns. 407 participants were assigned to the more intensive treatment group and 409 to the less intensive treatment group, of whom 404 patients in the more intensive treatment group and 406 patients in the less intensive treatment group had primary outcome data available. The likelihood of poor functional outcome was greater in the more intensive treatment group than the less intensive treatment group (common OR 1·37 [95% CI 1·07-1·76]). Compared with the less intensive treatment group, the more intensive treatment group had more early neurological deterioration (common OR 1·53 [95% 1·18-1·97]) and major disability at 90 days (OR 2·07 [95% CI 1·47-2·93]) but there were no significant differences in symptomatic intracerebral haemorrhage. There were no significant differences in serious adverse events or mortality between groups.

INTERPRETATION

Intensive control of systolic blood pressure to lower than 120 mm Hg should be avoided to prevent compromising the functional recovery of patients who have received endovascular thrombectomy for acute ischaemic stroke due to intracranial large-vessel occlusion.

FUNDING

The Shanghai Hospital Development Center; National Health and Medical Research Council of Australia; Medical Research Futures Fund of Australia; China Stroke Prevention; Shanghai Changhai Hospital, Science and Technology Commission of Shanghai Municipality; Takeda China; Hasten Biopharmaceutic; Genesis Medtech; Penumbra.

Advancing the Real-World Evidence for Medical Devices through Coordinated Registry Networks

Objectives

Generating and using real-world evidence (RWE) is a pragmatic solution for evaluating health technologies. RWE is recognized by regulators, health technology assessors, clinicians, and manufacturers as a valid source of information to support their decision-making. Well-designed registries can provide RWE and become more powerful when linked with electronic health records and administrative databases in coordinated registry networks (CRNs). Our objective was to create a framework of maturity of CRNs and registries, so guiding their development and the prioritization of funding.

Design, setting, and participants

We invited 52 stakeholders from diverse backgrounds including patient advocacy groups, academic, clinical, industry and regulatory experts to participate on a Delphi survey. Of those invited, 42 participated in the survey to provide feedback on the maturity framework for CRNs and registries. An expert panel reviewed the responses to refine the framework until the target consensus of 80% was reached. Two rounds of the Delphi were distributed via Qualtrics online platform from July to August 2020 and from October to November 2020.

Main outcome measures

Consensus on the maturity framework for CRNs and registries consisted of seven domains (unique device identification, efficient data collection, data quality, product life cycle approach, governance and sustainability, quality improvement, and patient-reported outcomes), each presented with five levels of maturity.

Results

Of 52 invited experts, 41 (79.9%) responded to round 1; all 41 responded to round 2; and consensus was reached for most domains. The expert panel resolved the disagreements and final consensus estimates ranged from 80.5% to 92.7% for seven domains.

Conclusions

We have developed a robust framework to assess the maturity of any CRN (or registry) to provide reliable RWE. This framework will promote harmonization of approaches to RWE generation across different disciplines and health systems. The domains and their levels may evolve over time as new solutions become available.

Michael Sedbon: Explorations in Coupling Artificial and Natural Systems

As a timely artist investigating the potential of coupling natural systems with silicon-based systems, Michael Sedbon's work suggests a unique perspective on the relationship of manmade information processing technologies to computing, intelligence, and consciousness found in nature. His hope for a better world through building systems based on biomimicry exploration piqued our interest as we interviewed him for this article.

Enhancing generalisability of stroke clinical trial results: illustrations from upper limb motor recovery trials

Introduction: Broadening eligibility criteria has been a focus to increase the generalisability of trial findings. Using upper limb motor trials conducted early post-stroke as the illustrative domain, we sought to (a) investigate whether the published aim and conclusion statements adequately reflect the generalisability of findings and, (b) explore internal validity and feasibility as constraints to achieving generalisability.

Methods: We systematically applied a conceptual model of a trial sampling process to published literature from systematic review and prospective cross-sectional data. The eligibility criteria reported and used to exclude patients were classified by consensus as related to safety, internal validity, feasibility, or a combination thereof. Categorical data were reported as counts/proportions and continuous data were reported as median (IQR).

Results: Thirty trials (n=1,638 participants) were included in the published literature and 1,013 patients in the prospective dataset. Thirty-seven per cent of trials did not describe their target population in the aim and conclusion, and 80% did not report all trial screening data. Eligibility criteria related to internal validity were the most common type reported and applied to exclude patients across both datasets. In the prospective dataset, 70% of patients were excluded for more than one reason.

Conclusion: Key information to support the generalisability of trial findings was insufficiently reported in published upper limb motor research conducted early post-stroke. Broadening eligibility criteria alone is unlikely to sufficiently improve trial inclusivity due to internal validity constraints. Trials could achieve inclusivity through targeting multiple subpopulations, that in combination, produce clinically relevant results that are applicable to a broader population.

Factor XIa inhibition with asundexian after acute non-cardioembolic ischaemic stroke (PACIFIC-Stroke): an international, randomised, double-blind, placebo-controlled, phase 2b trial

BACKGROUND

Asundexian (Bayer AG, Leverkusen, Germany), an oral small molecule factor XIa (FXIa) inhibitor, might prevent thrombosis without increasing bleeding. Asundexian's effect for secondary prevention of recurrent stroke is unknown.

METHODS

In this randomised, double-blind, placebo-controlled, phase 2b dose-finding trial (PACIFIC-Stroke), patients with acute (within 48 h) non-cardioembolic ischaemic stroke were recruited from 196 hospitals in 23 countries. Patients were eligible if they were aged 45 years or older, to be treated with antiplatelet therapy, and able to have a baseline MRI (either before or within 72 h of randomisation). Eligible participants were randomly assigned (1:1:1:1), using an interactive web-based response system and stratified according to anticipated antiplatelet therapy (single vs dual), to once daily oral asundexian (BAY 2433334) 10 mg, 20 mg, or 50 mg, or placebo in addition to usual antiplatelet therapy, and were followed up during treatment for 26-52 weeks. Brain MRIs were obtained at study entry and at 26 weeks or as soon as possible after treatment discontinuation. The primary efficacy outcome was the dose-response effect on the composite of incident MRI-detected covert brain infarcts and recurrent symptomatic ischaemic stroke at or before 26 weeks after randomisation. The primary safety outcome was major or clinically relevant non-major bleeding as defined by International Society on Thrombosis and Haemostasis criteria. The efficacy outcome was assessed in all participants assigned to treatment, and the safety outcome was assessed in all participants who received at least one dose of study treatment. This study is registered with ClinicalTrials.gov, NCT04304508, and is now complete.

FINDINGS

Between June 15, 2020, and July 22, 2021, 1880 patients were screened and 1808 participants were randomly assigned to asundexian 10 mg (n=455), 20 mg (n=450), or 50 mg (n=447), or placebo (n=456). Mean age was 67 years (SD 10) and 615 (34%) participants were women, 1193 (66%) were men, 1505 (83%) were White, and 268 (15%) were Asian. The mean time from index stroke to randomisation was 36 h (SD 10) and median baseline National Institutes of Health Stroke Scale score was 2·0 (IQR 1·0-4·0). 783 (43%) participants received dual antiplatelet treatment for a mean duration of 70·1 days (SD 113·4) after randomisation. At 26 weeks, the primary efficacy outcome was observed in 87 (19%) of 456 participants in the placebo group versus 86 (19%) of 455 in the asundexian 10 mg group (crude incidence ratio 0·99 [90% CI 0·79-1·24]), 99 (22%) of 450 in the asundexian 20 mg group (1·15 [0·93-1·43]), and 90 (20%) of 447 in the asundexian 50 mg group (1·06 [0·85-1·32]; t statistic -0·68; p=0·80). The primary safety outcome was observed in 11 (2%) of 452 participants in the placebo group versus 19 (4%) of 445 in the asundexian 10 mg group, 14 (3%) of 446 in the asundexian 20 mg group, and 19 (4%) of 443 in the asundexian 50 mg group (all asundexian doses pooled vs placebo hazard ratio 1·57 [90% CI 0·91-2·71]).

INTERPRETATION

In this phase 2b trial, FXIa inhibition with asundexian did not reduce the composite of covert brain infarction or ischaemic stroke and did not increase the composite of major or clinically relevant non-major bleeding compared with placebo in patients with acute, non-cardioembolic ischaemic stroke.

FUNDING

Bayer AG.

Effect of the Shanghai Stroke Service System (4S) on the Quality of Stroke Care and Outcomes: A Prospective Quality Improvement Project

BACKGROUND

In China, disparities in the quality of stroke care still exist and implementing quality improvement is still a challenge.

AIMS

To determine whether the intervention by Shanghai Stroke Service System (4S) has helped to improve adherence to stroke-care guidelines and patient outcome.

METHODS

4S is a regional stroke network with real-time data extraction among its 61 stroke centers in Shanghai. A total of 11 key performance indicators (KPIs) were evaluated. The primary outcomes were a composite measure and an all-or-none measure of adherence to 11 KPIs. The secondary outcomes were length of hospital stay and in-hospital mortality.

RESULTS

The study enrolled 92,395 patients (mean age 69.0±12.5 years, 65.2% men) with acute ischemic stroke hospitalized within 7 days of onset in Shanghai from January 2015 to December 2020. More patients received guideline recommended care between 2018-2020 than those between 2015-2017 (composite measure 87.1% vs 83.6%; absolute difference 2.9%, 95%CI [2.7% to 3.2%], P<0.001; all-or-none measure 49.2% vs 44.8% patients; absolute difference 3.5%, 95%CI [2.7% to 4.2%], P<0.001). Further analysis of individual KPIs showed an absolute increase in 6 KPIs ranging from 3.4% to 8.9% (P<0.001 for all comparisons). Compared to 2015-2017, hospital length of stay was shorter (10.95 vs 11.90 days; absolute difference -1.08, 95%CI [-1.18 to -0.99], P<0.001) and in-hospital mortality was significantly reduced (RR 0.88, 95% CI [0.79-0.98]; P=0.01) in 2018-2020.

CONCLUSIONS

The 4S intervention was associated with increased adherence to the stroke-care guidelines, which further translated to improved clinical outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02735226.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Abstract 454: TumorMapr™ analytical software platform: Unbiased spatial analytics and explainable AI (xAI) platform for generating data, extracting information, and creating knowledge from multi to hyperplexed fluorescence and/or mass spectrometry image datasets

Background: The current computational analyses of multi to hyperplexed fluorescence and/or mass spectrometry image datasets from patient pathology samples are not powerful enough to extract the maximum amount of information or to create the detailed knowledge that is required to advance precision medicine in pathology, including the development of personalized therapeutic strategies, identification of potential novel targets for drug discovery, selection of optimal patient cohorts for clinical trials, and improvement of the predictive power of prognostics/diagnostics.

Methods: TumorMapr harnesses the computational power of proprietary, unbiased spatial analytics, spatial systems pathology, and explainable artificial intelligence (xAI) to extract information and to create knowledge from patient primary disease pathology samples imaged on any of the existing fluorescence and/or mass spectrometry imaging platforms.

Results: To demonstrate the generalizability and utility of the TumorMapr platform, we apply it on two different datasets: hyperplexed immunofluorescence-based colorectal cancer data (51 biomarkers, 431 patients) and imaging mass cytometry-based breast cancer data (35 biomarkers, 281 patients). The TumorMapr platform (i) unlike the biased intensity thresholding approaches, the unbiased and automated functional cell phenotyping discovers a continuum of cell types and cell states, including transitional, multi-transitional cell states and fusion cell types that are critical for disease progression; (ii) derives microdomains with tumor promoting and tumor suppressing properties that are highly predictive of disease progression and response to therapy; (iii) spatial systems pathology analysis taps into the current network biology knowledge databases to derive pathway interactions and signaling networks, identify novel biomarkers and potential molecular targets and drugs, in the spatial context of each microdomain; (iv) xAI application guide, for example, in the case of predicting 5-year risk of recurrence in CRC patients, provides explanations in the form of microdomain-specific networks that are driving disease progression. Using the TumorMapr pipeline we created a prognostic test that shows a vastly superior performance over current approaches in predicting 5-yr risk of recurrence in CRC patients. Further, the TumorMapr platform enables building a rich outcome-specific library of microdomains to directly apply on prospective tissue samples for a companion diagnostic test that predicts disease outcomes.

Citation Format: Samantha Panakkal, Brian Falkenstein, Akif Burak Tosun, Bruce Campbell, Michael Becich, Jeffrey Fine, D. Lansing Taylor, S. Chakra Chennubhotla, Filippo Pullara. TumorMapr™ analytical software platform: Unbiased spatial analytics and explainable AI (xAI) platform for generating data, extracting information, and creating knowledge from multi to hyperplexed fluorescence and/or mass spectrometry image datasets [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 454.

Reporting guideline for the early-stage clinical evaluation of decision support systems driven by artificial intelligence: DECIDE-AI

A growing number of artificial intelligence (AI)-based clinical decision support systems are showing promising performance in preclinical, in silico evaluation, but few have yet demonstrated real benefit to patient care. Early-stage clinical evaluation is important to assess an AI system's actual clinical performance at small scale, ensure its safety, evaluate the human factors surrounding its use and pave the way to further large-scale trials. However, the reporting of these early studies remains inadequate. The present statement provides a multi-stakeholder, consensus-based reporting guideline for the Developmental and Exploratory Clinical Investigations of DEcision support systems driven by Artificial Intelligence (DECIDE-AI). We conducted a two-round, modified Delphi process to collect and analyze expert opinion on the reporting of early clinical evaluation of AI systems. Experts were recruited from 20 pre-defined stakeholder categories. The final composition and wording of the guideline was determined at a virtual consensus meeting. The checklist and the Explanation & Elaboration (E&E) sections were refined based on feedback from a qualitative evaluation process. In total, 123 experts participated in the first round of Delphi, 138 in the second round, 16 in the consensus meeting and 16 in the qualitative evaluation. The DECIDE-AI reporting guideline comprises 17 AI-specific reporting items (made of 28 subitems) and ten generic reporting items, with an E&E paragraph provided for each. Through consultation and consensus with a range of stakeholders, we developed a guideline comprising key items that should be reported in early-stage clinical studies of AI-based decision support systems in healthcare. By providing an actionable checklist of minimal reporting items, the DECIDE-AI guideline will facilitate the appraisal of these studies and replicability of their findings.

Tenecteplase versus Alteplase for Stroke Thrombolysis Evaluation Trial in the Ambulance (Mobile Stroke Unit-TASTE-A): protocol for a prospective randomised, open-label, blinded endpoint, phase II superiority trial of tenecteplase versus alteplase for ischaemic stroke patients presenting within 4.5 hours of symptom onset to the mobile stroke unit

INTRODUCTION

Mobile stroke units (MSUs) equipped with a CT scanner are increasingly being used to assess and treat stroke patients' prehospital with thrombolysis and transfer them to the most appropriate hospital for ongoing stroke care and thrombectomy when indicated. The effect of MSUs in both reducing the time to reperfusion treatment and improving patient outcomes is now established. There is now an opportunity to improve the efficacy of treatment provided by the MSU. Tenecteplase is a potent plasminogen activator, which may have benefits over the standard of care stroke lytic alteplase. Specifically, in the MSU environment tenecteplase presents practical benefits since it is given as a single bolus and does not require an infusion over an hour like alteplase.

OBJECTIVE

In this trial, we seek to investigate if tenecteplase, given to patients with acute ischaemic stroke as diagnosed on the MSU, improves the rate of early reperfusion.

METHODS AND ANALYSIS

TASTE-A is a prospective, randomised, open-label, blinded endpoint (PROBE) phase II trial of patients who had an ischaemic stroke assessed in an MSU within 4.5 hours of symptom onset. The primary endpoint is early reperfusion measured by the post-lysis volume of the CT perfusion lesion performed immediately after hospital arrival.

ETHICS AND DISSEMINATION

The study was approved by the Royal Melbourne Hospital Human Ethics committee. The findings will be published in peer-reviewed journals, presented at academic conferences and disseminated among consumer and healthcare professional audiences.

TRIAL REGISTRATION NUMBER

NCT04071613.

Prevalence and Significance of Impaired Microvascular Tissue Reperfusion Despite Macrovascular Angiographic Reperfusion (No-Reflow)

BACKGROUND AND OBJECTIVES

The relevance of impaired microvascular tissue-level reperfusion despite complete upstream macrovascular angiographic reperfusion (no-reflow) in human stroke remains controversial. We investigated the prevalence and clinical-radiologic features of this phenomenon and its associations with outcomes in 3 international randomized controlled thrombectomy trials with prespecified follow-up perfusion imaging.

METHODS

In a pooled analysis of the Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA; ClinicalTrials.gov NCT01492725), Tenecteplase Versus Alteplase Before Endovascular Therapy for Ischemic Stroke (EXTEND-IA TNK; NCT02388061), and Determining the Optimal Dose of Tenecteplase Before Endovascular Therapy for Ischaemic Stroke (EXTEND-IA TNK Part 2; NCT03340493) trials, patients undergoing thrombectomy with final angiographic expanded Treatment in Cerebral Infarction score of 2c to 3 score for anterior circulation large vessel occlusion and 24-hour follow-up CT or MRI perfusion imaging were included. No-reflow was defined as regions of visually demonstrable persistent hypoperfusion on relative cerebral blood volume or flow maps within the infarct and verified quantitatively by >15% asymmetry compared to a mirror homolog in the absence of carotid stenosis or reocclusion.

RESULTS

Regions of no-reflow were identified in 33 of 130 patients (25.3%), encompassed a median of 60.2% (interquartile range 47.8%-70.7%) of the infarct volume, and involved both subcortical (n = 26 of 33, 78.8%) and cortical (n = 10 of 33, 30.3%) regions. Patients with no-reflow had a median 25.2% (interquartile range 16.4%-32.2%, p < 0.00001) relative cerebral blood volume interside reduction and 19.1% (interquartile range 3.9%-28.3%, p = 0.00011) relative cerebral blood flow reduction but similar mean transit time (median -3.3%, interquartile range -11.9% to 24.4%, p = 0.24) within the infarcted region. Baseline characteristics were similar between patients with and those without no-reflow. The presence of no-reflow was associated with hemorrhagic transformation (adjusted odds ratio [aOR] 1.79, 95% confidence interval [CI] 2.32-15.57, p = 0.0002), greater infarct growth (β = 11.00, 95% CI 5.22-16.78, p = 0.00027), reduced NIH Stroke Scale score improvement at 24 hours (β = -4.06, 95% CI 6.78-1.34, p = 0.004) and being dependent or dead at 90 days as assessed by the modified Rankin Scale (aOR 3.72, 95% CI 1.35-10.20, p = 0.011) in multivariable analysis.

DISCUSSION

Cerebral no-reflow in humans is common, can be detected by its characteristic perfusion imaging profile using readily available sequences in the clinical setting, and is associated with posttreatment complications and being dependent or dead. Further studies evaluating the role of no-reflow in secondary injury after angiographic reperfusion are warranted.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that cerebral no-reflow on CT/MRI perfusion imaging at 24 hours is associated with posttreatment complications and poor 3-month functional outcome.

Common scale minimal sufficient balance: An improved method for covariate-adaptive randomization based on the Wilcoxon-Mann-Whitney odds ratio statistic

Minimal sufficient balance (MSB) is a recently suggested method for adaptively controlling covariate imbalance in randomized controlled trials in a manner which reduces the impact on randomness of allocation over other approaches by only intervening when the imbalance is sufficiently significant. Despite its improvements, the approach is unable to consider the relative clinical importance or magnitude of imbalance in each covariate weight, and ignores any imbalance which is not statistically significant, even when these imbalances may collectively justify intervention. We propose the common scale MSB (CS‐MSB) method which addresses these limitations, and present simulation studies comparing our proposed method to MSB. We demonstrate that CS‐MSB requires less intervention than MSB to achieve the same level of covariate balance, and does not adversely impact either statistical power or Type‐I error.

Abstract 126: Cerebral Perfusion Imaging And Posterior Circulation ASPECTS Identify Stroke Patients Who Benefit From Basilar Artery Thrombectomy

Introduction: Acute ischemic stroke due to basilar artery occlusion (AIS-BAO) results in significant morbidity and mortality. Endovascular thrombectomy (ET) has not been shown to improve outcomes in AIS-BAO patients in randomized trials, which may be due to insufficient selection before ET. We determined whether the Critical Area Perfusion Score (CAPS) and posterior circulation ASPECTS (PC-ASPECTS) predict a favorable response to ET.

Methods: We performed a multicenter retrospective study of AIS-BAO patients with perfusion imaging prior to ET. PC-ASPECTS was determined on NCCT by evaluating the cerebellum (1 point/hemisphere), pons (2 points), midbrain (2 points), thalamus (1 point/hemisphere), and posterior cerebral artery (1 point/hemisphere) territories, and points were subtracted for hypodensity in these regions. CAPS was quantified severe hypoperfusion (Tmax >10s) in cerebellum (1 point/hemisphere), pons (2 points), midbrain and/or thalamus (2 points). The primary outcome was a favorable outcome 90-days after ET (modified Rankin Scale [mRS] 0-3).

Results: 89 patients were included. CAPS (AUC=0.70 [95% CI: 0.59-0.80]; p=0.002) and PC-ASPECTS (AUC=0.63 [95% CI: 0.52-0.75]; p=0.034) both predicted favorable outcomes in a receiver operating curve analysis, but there was no difference between the two (p=0.434). After dichotomization, patients with favorable CAPS (≤3) and PC-ASPECTS (≥7) were more likely to achieve a good functional outcome after successful reperfusion after ET (Figure). However, an unfavorable CAPS (>3) was associated with poor outcomes despite successful thrombectomy in all patients, whereas 22% of patients with unfavorable PC-ASPECTS (<7) still achieved favorable outcomes with reperfusion after ET (Figure).

Conclusions: CAPS and PC-ASPECTS both identify AIS-BAO patients who are likely to have a favorable clinical response to ET. CAPS, but not PC-ASPECTS, appears to accurately identify a subgroup in whom ET may be futile.

Abstract 41: Functional Outcome Of Patients 85 Years Or Older With Acute Ischemic Stroke Following Endovascular Treatment - A Substudy Of The Hermes Meta-analysis

Introduction: Previous studies have reported poor outcomes and high rates of mortality following endovascular therapy (EVT) for ischemic stroke in older patients. However, patients ≥85 years were underrepresented in most randomized trials. Our aim was to study the influence of age on outcome and EVT effect for ischemic stroke in patients aged ≥85 years.

Methods: Data were from the HERMES collaboration, a meta-analysis of 7 randomized trials that tested the efficacy of EVT. Two multivariable ordinal logistic regression were used to compare the association between EVT and 90-day functional outcome (modified Rankin Scale, primary outcome) in patients ≥85 years old to those who were younger. Secondary outcomes included mortality at 90 days and symptomatic intracranial hemorrhage (sICH) at 24 hours.

Results: We included 1764 patients in the analysis, of whom 77 (4.4%) were ≥85 years old. While patients ≥85 years had worse outcomes (adjusted odds ratio [aOR] 0.26 (95%CI:0.14-0.48) and higher mortality rates (aOR:3.28, 95%CI:1.54-6.97) compared to those <85 years, a significant benefit of EVT was observed in the ≥85-year-old patient subgroup (common OR:4.20 (95%CI:1.56-11.32, Figure). Patients ≥85 years undergoing EVT had lower rates of mortality than those in the control group (31% vs. 54%, p<0.01). Age ≥85 years was not significantly associated with higher rates of sICH (adjusted cOR:2.3, 95%CI:0.59-8.93).

Conclusion: Patients ≥85 years old with independent premorbid function more often achieve good functional outcomes when treated with EVT compared to conservative management, with lower rates of mortality and no differences in sICH rates. EVT should therefore not be withheld in this subgroup.

Abstract 44: Safety Of Tenecteplase And Alteplase In Tandem Lesion Stroke: A Pooled Analysis Of The Extend-IA TNK Trials

Introduction: The efficacy of tenecteplase (TNK) in patients with tandem lesions (TL) in the anterior circulation is unknown. The longer half-life of TNK could potentially lead to increased hemorrhage, especially in patients who require stenting of the extracranial internal carotid artery (eICA) and subsequent antiplatelet therapy. We assessed the efficacy and safety of TNK in a pooled analysis of the EXTEND-IA TNK trials.

Methods: We compared the treatment effect of TNK (pooled analysis of 0.25 and 0.40mg/kg dosing) with alteplase (tPA), stratifying for TL presence. A TL was defined as a combination of eICA pathology (ipsilateral stenosis >70% or occlusion) and intracranial LVO. Outcomes evaluated include 90-day mRS, intracranial reperfusion at initial angiographic assessment, mortality, ICH (symptomatic [sICH] and parenchymal hematoma [PH]). Treatment effect was adjusted for baseline NIHSS, age, and time from symptom onset to puncture via mixed effects proportional odds and logistic regression models.

Results: Of 483 patients with an anterior circulation occlusion, 71/483 (15%) patients had a TL and 43/71 (61%) patients required eICA stenting. In TL patients, reperfusion at initial angiographic assessment was observed in 11/56 (20%) of patients treated with TNK vs. 1/15 (7%) patients treated with tPA (aOR:3.71; 95% CI:0.42-32.75). sICH was observed in 4/71(6%) TL vs 7/412 (2%) nonTL patients (p=0.04). Among TL patients, sICH occurred in 4/56 (7%) patients treated with TNK vs 0/15 (0%) tPA treated patients (p=0.57); sICH occurred in 2/40 (5%) of the 0.25mg/kg TNK group and 2/16 (12.5%) of the 0.40mg/kg TNK group. PH was observed in 6/56 (11%) patients treated with TNK vs 0/15 (0%) tPA treated patients (p=0.33). 90-day mRS (TNK median 2 vs. tPA median 4, acOR:1.21; 95% CI:0.42-3.48), mortality (TNK: 5 [9%] vs. tPA: 3 [20%], aOR:0.45; 95% CI:0.08-2.50), and eICA stenting (TNK: 35 [64%] vs. tPA: 8 [57%], p=0.65) rates did not differ between the two treatment groups.

Conclusions: Although patients with TL in the anterior circulation were at higher risk of hemorrhagic complications, these did not significantly differ between the TNK and tPA groups. A numeric increase in bleeding with TNK was not accompanied by an increase in mortality or worse functional outcome.

Abstract WMP6: Trendelenburg (Head Down) Positioning In Acute Large Vessel Occlusion Ischemic Stroke Improves Penumbral Perfusion And Is Well-tolerated: The Head-start Study

Introduction: It is uncertain whether lowered head position improves penumbral perfusion in ischemic stroke. Although a transcranial Doppler trial in large vessel occlusion (LVO) patients suggested improvement, a large pragmatic clinical trial in mixed stroke patients was neutral. We tested the tolerability and effect on penumbral perfusion of 20-degree head-down (Trendelenburg) positioning in patients with acute LVO stroke using automated quantitative CT perfusion (CTP).

Methods: We enrolled LVO patients aged ≥60, 0-24h after onset, with ≥30mL anterior circulation CTP lesion volume (delay time [DT]>3, MISTAR software). CTP was repeated after 5 minutes of 20-degree Trendelenburg positioning using a custom-designed foam wedge. Neurological status (National Institutes of Health Stroke Scale [NIHSS]) and blood pressure were recorded in routine (30 degree up) and Trendelenburg position. Trendelenburg positioning was maintained for 24h if perfusion lesion volume significantly decreased (≥5mL) and reperfusion treatment was suboptimal.

Results: The target of 25 patients were enrolled (14 [56%] male, median age 76 (interquartile range [IQR]71-84), baseline modified Rankin scale score 0 [IQR0-0], median NIHSS 20 [IQR 13-24]). Most patients (15/25 [60%]) had an acute M1 middle cerebral artery (MCA) occlusion, 6 (24%) an occluded M2 MCA and 4 (16%) an occluded ICA. Stroke etiology was predominantly (15/25 [60%]) cardioembolic.Median (IQR) DT>3seconds lesion volume was significantly reduced by Trendelenburg compared with conventional horizontal CT positioning (114mL [94-204] vs 149mL [76-153] p=0.0027)). This was not explained by changes in blood pressure, which was unaltered (mean 148mmHg (+/- standard deviation 29) vs 143 (+/-27); p=0.129). Head position did not alter clinical severity (NIHSS 13 [IQR 9-28]) in both positions). A significant lesion volume reduction with Trendelenburg positioning was seen in 15/25 patients (60%); 7 received continued Trendelenburg positioning due to incomplete reperfusion. Head down positioning was well tolerated in the majority (4/7 [57%]), without serious adverse events.

Conclusion: Head-down (Trendelenburg) positioning improves penumbral perfusion in acute LVO ischemic stroke and is well-tolerated.

Abstract 43: Comparative Effectiveness Of Routine Tenecteplase Thrombolysis In Acute Stroke Compared With Alteplase: An INternational Collaboration (CERTAIN Collaboration): Rates Of Symptomatic Intracranial Hemorrhage

Introduction: Despite pharmacological and practical advantages for tenecteplase (TNK) over alteplase (ALT), no differences were observed in percent of symptomatic intracranial hemorrhage (sICH) in randomized trials (fewer than 900 total patients for either treatment). We compared rates of sICH in patients treated with either drug, using a large, multicenter, international registry.

Methods: The CERTAIN collaboration is an ongoing registry of deidentified patient-level data of thrombolytic treated ischemic stroke from various hospitals/programs in New Zealand, Australia, and the United States that have used ALT or TNK since July 1, 2018. Standardized data were abstracted and harmonized from local or regional clinical registries. We defined sICH as clinical worsening of at least 4 points on NIHSS, attributed to parenchymal hematoma, subarachnoid or intraventricular hemorrhage. We used logistic regression for binary variables, adjusting sICH differences for age, baseline NIHSS, thrombectomy, and source hospital network and Mann-Whitney test for continuous baseline variables.

Results: A total of 7891 patients were included in the initial analysis. The TNK group was older, more likely to be male, had higher NIHSS, and more frequently underwent mechanical thrombectomy (Table. Sample Characteristics). The sICH rate was 3.71% for ALT and 2.13% for TNK: adjusted OR (95%CI) = 0.49 (0.31-0.76) p=0.002. For patients not undergoing thrombectomy after thrombolytic, the sICH rate was 3.00% for ALT and 1.74% for TNK, adjusted OR (95%CI) = 0.48 (0.27-0.87), p=0.016. For thrombectomy treated cases, sICH rate was 6.80% for ALT and 2.80% for TNK, adjusted OR (95%CI) 0.60 (0.31-1.16), p=0.129.

Conclusion: In this preliminary analysis from a large, multicenter registry, ischemic stroke treated with tenecteplase was associated with a lower rate of sICH than with alteplase. An updated analysis with patient data from additional sites will be presented at the Conference.