Publications by authors named "Mark W Parsons"

170 Publications

Predicting Infarct Core From Computed Tomography Perfusion in Acute Ischemia With Machine Learning: Lessons From the ISLES Challenge.

Stroke 2021 May 7:STROKEAHA120030696. Epub 2021 May 7.

Department of Radiology, Stanford University, CA (G.Z.).

Background And Purpose: The ISLES challenge (Ischemic Stroke Lesion Segmentation) enables globally diverse teams to compete to develop advanced tools for stroke lesion analysis with machine learning. Detection of irreversibly damaged tissue on computed tomography perfusion (CTP) is often necessary to determine eligibility for late-time-window thrombectomy. Therefore, the aim of ISLES-2018 was to segment infarcted tissue on CTP based on diffusion-weighted imaging as a reference standard.

Methods: The data, from 4 centers, consisted of 103 cases of acute anterior circulation large artery occlusion stroke who underwent diffusion-weighted imaging rapidly after CTP. Diffusion-weighted imaging lesion segmentation was performed manually and acted as a reference standard. The data were separated into 63 cases for training and 40 for testing, upon which quality metrics (dice score coefficient, Hausdorff distance, absolute lesion volume difference, etc) were computed to rank methods based on their overall performance.

Results: Twenty-four different teams participated in the challenge. Median time to CTP was 185 minutes (interquartile range, 180-238), the time between CTP and magnetic resonance imaging was 36 minutes (interquartile range, 25-79), and the median infarct lesion size was 15.2 mL (interquartile range, 5.7-45). The best performance for Dice score coefficient and absolute volume difference were 0.51 and 10.1 mL, respectively, from different teams. Based on the ranking criteria, the top team's algorithm demonstrated for average Dice score coefficient and average absolute volume difference 0.51 and 10.2 mL, respectively, outperforming the conventional threshold-based method (dice score coefficient, 0.3; volume difference, 15.3). Diverse algorithms were used, almost all based on deep learning, with top-ranked approaches making use of the raw perfusion data as well as methods to synthetically generate complementary information to boost prediction performance.

Conclusions: Machine learning methods may predict infarcted tissue from CTP with improved accuracy compared with threshold-based methods used in clinical routine. This dataset will remain public and can be used to test improvement in algorithms over time.
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http://dx.doi.org/10.1161/STROKEAHA.120.030696DOI Listing
May 2021

The ischemic penumbra: From concept to reality.

Int J Stroke 2020 12 1:1747493020975229. Epub 2020 Dec 1.

Institute of Psychiatry and Neuroscience of Paris (IPNP), Université de Paris, Paris, France.

The discovery that brain tissue could potentially be salvaged from ischaemia due to stroke, has led to major advances in the development of therapies for ischemic stroke. In this review, we detail the advances in the understanding of this area termed the ischaemic penumbra, from its discovery to the evolution of imaging techniques, and finally some of the treatments developed. Evolving from animal studies from the 70s and 80s and translated to clinical practice, the field of ischemic reperfusion therapy has largely been guided by an array of imaging techniques developed to positively identify the ischemic penumbra, including positron emission tomography, computed tomography and magnetic resonance imaging. More recently, numerous penumbral identification imaging studies have allowed for a better understanding of the progression of the ischaemic core at the expense of the penumbra, and identification of patients than can benefit from reperfusion therapies in the acute phase. Importantly, 40 years of critical imaging research on the ischaemic penumbra have allowed for considerable extension of the treatment time window and better patient selection for reperfusion therapy. The translation of the penumbra concept into routine clinical practice has shown that "tissue is at least as important as time."
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http://dx.doi.org/10.1177/1747493020975229DOI Listing
December 2020

Does Intravenous Thrombolysis Within 4.5 to 9 Hours Increase Clot Migration Leading to Endovascular Inaccessibility?

Stroke 2021 Mar 16;52(3):1083-1086. Epub 2021 Feb 16.

Department of Medicine and Neurology, Melbourne Brain Centre at the Royal Melbourne Hospital (A.B., H.M., B.C.V.C., M.W.P., S.M.D., G.A.D., B.Y.), University of Melbourne, Parkville, Australia.

Background And Purpose: Distal clot migration is a recognized event following intravenous thrombolysis (IVT) in the setting of acute ischemic stroke. Of note, clots that were initially retrievable by endovascular thrombectomy may migrate to a distal nonretrievable location and compromise clinical outcome. We investigated the incidence of clot migration leading to clot inaccessibility following IVT in the time window of 4.5 to 9 hours.

Methods: We performed a retrospective analysis of the EXTEND trial (Extending the Time for Thrombolysis in Emergency Neurological Deficits) data. Baseline and 12- to 24-hour follow-up clot location was determined on computed tomography angiogram or magnetic resonance angiogram. The incidence of clot migration leading to a change from retrievable to nonretrievable location was identified and compared between the two treatment groups (IVT versus placebo).

Results: Two hundred twenty patients were assessed. Clot migration from a retrievable to nonretrievable location occurred in 37 patients: 21 patients (19.3%) in the placebo group and 16 patients (14.4%) in the IVT group. No significant difference was identified in the incidence of clot migration leading to inaccessibility between groups (=0.336).

Conclusions: Our results did not show increased clot migration leading to clot inaccessibility in patients treated with IVT.
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http://dx.doi.org/10.1161/STROKEAHA.120.030661DOI Listing
March 2021

What Is the "Optimal" Target Mismatch Criteria for Acute Ischemic Stroke?

Front Neurol 2020 13;11:590766. Epub 2021 Jan 13.

Melbourne Brain Centre, University of Melbourne, Parkville, VIC, Australia.

We aimed to compare Perfusion Imaging Mismatch (PIM) and Clinical Core Mismatch (CCM) criteria in ischemic stroke patients to identify the effect of these criteria on selected patient population characteristics and clinical outcomes. Patients from the INternational Stroke Perfusion Imaging REgistry (INSPIRE) who received reperfusion therapy, had pre-treatment multimodal CT, 24-h imaging, and 3 month outcomes were analyzed. Patients were divided into 3 cohorts: endovascular thrombectomy (EVT), intravenous thrombolysis alone with large vessel occlusion (IVT-LVO), and intravenous thrombolysis alone without LVO (IVT-nonLVO). Patients were classified using 6 separate mismatch criteria: PIM-using 3 different measures to define the perfusion deficit (Delay Time, Tmax, or Mean Transit Time); or CCM-mismatch between age-adjusted National Institutes of Health Stroke Scale and CT Perfusion core, defined as relative cerebral blood flow <30% within the perfusion deficit defined in three ways (as above). We assessed the eligibility rate for each mismatch criterion and its ability to identify patients likely to respond to treatment. There were 994 patients eligible for this study. PIM with delay time (PIM-DT) had the highest inclusion rate for both EVT (82.7%) and IVT-LVO (79.5%) cohorts. In PIM positive patients who received EVT, recanalization was strongly associated with achieving an excellent outcome at 90-days (e.g., PIM-DT: mRS 0-1, adjusted OR 4.27, = 0.005), whereas there was no such association between reperfusion and an excellent outcome with any of the CCM criteria (all > 0.05). Notably, in IVT-LVO cohort, 58.2% of the PIM-DT positive patients achieved an excellent outcome compared with 31.0% in non-mismatch patients following successful recanalization ( = 0.006). PIM-DT was the optimal mismatch criterion in large vessel occlusion patients, combining a high eligibility rate with better clinical response to reperfusion. No mismatch criterion was useful to identify patients who are most likely response to reperfusion in non-large vessel occlusion patients.
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http://dx.doi.org/10.3389/fneur.2020.590766DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7874100PMC
January 2021

Automated estimation of ischemic core prior to thrombectomy: comparison of two current algorithms.

Neuroradiology 2021 Feb 12. Epub 2021 Feb 12.

Melbourne Brain Centre at Royal Melbourne Hospital, University of Melbourne, Grattan St, Parkville, Victoria, 3050, Australia.

Purpose: Endovascular thrombectomy (EVT) improves clinical outcomes in ischemic stroke with large vessel occlusion. Clinical benefits are inversely proportional to size of the pre-treatment ischemic core. This study compared estimated ischemic core volumes by two different CT perfusion (CTP) automated algorithms to the gold standard follow-up infarct volume using diffusion-weighted imaging (DWI) to assess for congruence, and thus eligibility for EVT.

Methods: Retrospective, single-center cohort study of 102 patients presenting to a comprehensive stroke center between 2012 and 2018. Inclusion criteria were CT perfusion prior to EVT, successful EVT with mTIBI 2b-3 reperfusion, and DWI post-EVT. CTP data were retrospectively processed by two algorithms: "delay and dispersion insensitive deconvolution" (DISD, RAPID software) versus "delay and dispersion corrected single value decomposition" (ddSVD, Mistar software), using commercially available software. Core volumes were compared to follow up DWI using independent software (MRIcron). Agreement between each algorithm and DWI was estimated using Lin's concordance coefficient and analyzed using reduced major axis regression.

Results: We included 102 patients. Both algorithms had excellent agreement with DWI (Lin's concordance coefficients: DISD 0.8 (95% CI: 0.73; 0.87), ddSVD 0.92 (95% CI: 0.89; 0.95). Compared to ddSVD (reduced major axis slope = 0.95), DISD exhibited a larger extent of proportional bias (slope = 1.12).

Conclusion: The ddSVD algorithm better correlates with DWI follow-up infarct volume than DISD processing. The DISD algorithm overestimated larger ischemic cores which may lead to patient exclusion from thrombectomy based on selection by core volume.
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http://dx.doi.org/10.1007/s00234-021-02651-9DOI Listing
February 2021

Low-Dose vs Standard-Dose Alteplase in Acute Lacunar Ischemic Stroke: The ENCHANTED Trial.

Neurology 2021 03 3;96(11):e1512-e1526. Epub 2021 Feb 3.

From The George Institute for Global Health, Faculty of Medicine (Z.Z., C.D., C.X., S. Yoshimura, C.C., T.T.-Y., A.M., X.C., M.L.H., M.W., J.C., C.S.A.), and South Western Clinical School (M.W.P.), University of New South Wales Sydney, Australia; Department of Radiology (Z.Z., J.X.), Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, China; Department of Neurology (C.D., C.C., C.S.A.), Royal Prince Alfred Hospital, Sydney Health Partners; Sydney Medical School (C.D., C.C.), University of Sydney, Australia; Department of Neurosurgery (C.X.), West China Hospital, Sichuan University, Chengdu, China; Department of Cerebrovascular Medicine (S. Yoshimura, T.T.-Y.), National Cerebral and Cardiovascular Center, Osaka; Department of Neurology and Neuroscience (T.T.-Y.), Nagoya City University Graduate School of Medical Science, Japan; Department of Neurology (S. You), the Second Affiliated Hospital of Soochow University, Suzhou, China; The George Institute for Global Health, School of Public Health (M.W.), Imperial College, London; Department of Cardiovascular Sciences and NIHR Leicester Biomedical Research Center (T.G.R.), University of Leicester, UK; Melbourne Brain Centre, Royal Melbourne Hospital University Department of Medicine (M.W.P.), University of Melbourne, Australia; Departments of Clinical Neurosciences and Radiology, Hotchkiss Brain Institute, Cumming School of Medicine (A.M.D.), University of Calgary, Canada; Westmead Applied Research Centre (R.I.L.), University of Sydney, Australia; Division of Neuroimaging Sciences, Edinburgh Imaging and Centre for Clinical Brain Sciences (G.M., J.M.W.), and UK Dementia Research Institute (J.M.W.), University of Edinburgh; and The George Institute China at Peking University Health Science Center (C.S.A.), Beijing, China.

Objective: To determine any differential efficacy and safety of low- vs standard-dose IV alteplase for lacunar vs nonlacunar acute ischemic stroke (AIS), we performed post hoc analyzes from the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED) alteplase dose arm.

Methods: In a cohort of 3,297 ENCHANTED participants, we identified those with lacunar or nonlacunar AIS with different levels of confidence (definite/according to prespecified definitions based on clinical and adjudicated imaging findings. Logistic regression models were used to determine associations of lacunar AIS with 90-day outcomes (primary, modified Rankin Scale [mRS] scores 2-6; secondary, other mRS scores, intracerebral hemorrhage [ICH], and early neurologic deterioration or death) and treatment effects of low- vs standard-dose alteplase across lacunar and nonlacunar AIS with adjustment for baseline covariables.

Results: Of 2,588 participants with available imaging and clinical data, we classified cases as definite/probable lacunar (n = 490) or nonlacunar AIS (n = 2,098) for primary analyses. Regardless of alteplase dose received, lacunar AIS participants had favorable functional (mRS 2-6, adjusted odds ratio [95% confidence interval] 0.60 [0.47-0.77]) and other clinical or safety outcomes compared to participants with nonlacunar AIS. Low-dose alteplase (versus standard) had no differential effect on functional outcomes (mRS 2-6, 1.04 [0.87-1.24]) but reduced the risk of symptomatic ICH in all included participants. There were no differential treatment effects of low- vs standard-dose alteplase on all outcomes across lacunar and nonlacunar AIS (all ≥0.07).

Conclusions: We found no evidence from the ENCHANTED trial that low-dose alteplase had any advantages over standard dose for definite/probable lacunar AIS.

Classification Of Evidence: This study provides Class II evidence that for patients with lacunar AIS, low-dose alteplase had no additional benefit or safety over standard-dose alteplase.

Clinical Trial Registration: Clinicaltrials.gov identifier NCT01422616.
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http://dx.doi.org/10.1212/WNL.0000000000011598DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8032382PMC
March 2021

Automated Measurement of Computed Tomography Acute Ischemic Core in Stroke: Does the Emperor Have No Clothes?

Authors:
Mark W Parsons

Stroke 2021 Jan 12;52(2):642-644. Epub 2021 Jan 12.

University of NSW (UNSW) South Western Sydney Clinical School, Department of Neurology, Liverpool Hospital, Ingham Institute for Applied Medical Research, Australia.

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http://dx.doi.org/10.1161/STROKEAHA.120.032998DOI Listing
January 2021

Role of Computed Tomography Perfusion in Identification of Acute Lacunar Stroke Syndromes.

Stroke 2021 01 2;52(1):339-343. Epub 2020 Dec 2.

Hunter Medical Research Institute and University of Newcastle, Australia (C.G.-E., F.M., T.L., C.R.L., N.J.S., M.W.P.).

Background And Purpose: Lacunar syndromes correlate with a lacunar stroke on imaging in 50% to 60% of cases. Computed tomography perfusion (CTP) is becoming the preferred imaging modality for acute stroke triage. We aimed to estimate the sensitivity, specificity, and predictive values for noncontrast computed tomography and CTP in lacunar syndromes, and for cortical, subcortical, and posterior fossa regions.

Methods: A retrospective analysis of confirmed ischemic stroke patients who underwent acute CTP and follow-up magnetic resonance imaging between 2010 and 2018 was performed. Brain noncontrast computed tomography and CTP were assessed independently by 2 stroke neurologists. Receiver operating characteristic curve analysis was performed to estimate sensitivity, specificity, and area under the curve (AUC) for the detection of strokes in patients with lacunar syndromes using different CTP maps.

Results: We found 106 clinical lacunar syndromes, but on diffusion-weighted imaging, these consisted of 59 lacunar, 33 cortical, and 14 posterior fossa strokes. The discrimination of ischemia identification was very poor using noncontrast computed tomography in all 3 regions, but good for cortical (AUC, 0.82) and poor for subcortical and posterior regions (AUCs, 0.55 and 0.66) using automated core-penumbra maps. The addition of delay time and mean transient time maps substantially increased subcortical (AUC, 0.80) and slightly posterior stroke detection (AUC, 0.69).

Conclusions: Analysis of mean transient time and delay time maps in combination with core-penumbra maps improves detection of subcortical and posterior strokes.
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http://dx.doi.org/10.1161/STROKEAHA.120.030455DOI Listing
January 2021

Utility of Severity-Based Prehospital Triage for Endovascular Thrombectomy: ACT-FAST Validation Study.

Stroke 2021 01 22;52(1):70-79. Epub 2020 Dec 22.

Departments of Medicine and Neurology, Melbourne Brain Centre at The Royal Melbourne Hospital (H.Z., L.C., J.L.N., C.W., F.A., F.N., P.J.M., M.W.P., N.Y., S.M.D., B.C.V.C.), University of Melbourne, Australia.

Background And Purpose: Severity-based assessment tools may assist in prehospital triage of patients to comprehensive stroke centers (CSCs) for endovascular thrombectomy (EVT), but criticisms regarding diagnostic inaccuracy have not been adequately addressed. This study aimed to quantify the benefits and disadvantages of severity-based triage in a large real-world paramedic validation of the Ambulance Clinical Triage for Acute Stroke Treatment (ACT-FAST) algorithm.

Methods: Ambulance Victoria paramedics assessed the prehospital ACT-FAST algorithm in patients with suspected stroke from November 2017 to July 2019 following an 8-minute training video. All patients were transported to the nearest stroke center as per current guidelines. ACT-FAST diagnostic accuracy was compared with hospital imaging for the presence of large vessel occlusion (LVO) and need for CSC-level care (LVO, intracranial hemorrhage, and tumor). Patient-level time saving to EVT was modeled using a validated Google Maps algorithm. Disadvantages of CSC bypass examined potential thrombolysis delays in non-LVO infarcts, proportion of patients with false-negative EVT, and CSC overburdening.

Results: Of 517 prehospital assessments, 168/517 (32.5%) were ACT-FAST positive and 132/517 (25.5%) had LVO. ACT-FAST sensitivity and specificity for LVO was 75.8% and 81.8%, respectively. Positive predictive value was 58.8% for LVO and 80.0% when intracranial hemorrhage and tumor (CSC-level care) were included. Within the metropolitan region, 29/55 (52.7%) of ACT-FAST-positive patients requiring EVT underwent a secondary interhospital transfer. Prehospital bypass with avoidance of secondary transfers was modeled to save 52 minutes (95% CI, 40.0-61.5) to EVT commencement. ACT-FAST was false-positive in 8 patients receiving thrombolysis (8.1% of 99 non-LVO infarcts) and false-negative in 4 patients with EVT requiring secondary transfer (5.4% of 74 EVT cases). CSC bypass was estimated to over-triage 1.1 patients-per-CSC-per-week in our region.

Conclusions: The overall benefits of an ACT-FAST algorithm bypass strategy in expediting EVT and avoiding secondary transfers are estimated to substantially outweigh the disadvantages of potentially delayed thrombolysis and over-triage, with only a small proportion of EVT patients missed.
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http://dx.doi.org/10.1161/STROKEAHA.120.031467DOI Listing
January 2021

Multimodal Computed Tomography Increases the Detection of Posterior Fossa Strokes Compared to Brain Non-contrast Computed Tomography.

Front Neurol 2020 20;11:588064. Epub 2020 Nov 20.

Department of Neurology, John Hunter Hospital, Newcastle, NSW, Australia.

Multimodal computed tomography (mCT) (non-contrast CT, CT angiography, and CT perfusion) is not routinely used to assess posterior fossa strokes. We described the area under the curve (AUC) of brain NCCT, WB-CTP automated core-penumbra maps and comprehensive CTP analysis (automated core-penumbra maps and all perfusion maps) for posterior fossa strokes. We included consecutive patients with signs and symptoms of posterior fossa stroke who underwent acute mCT and follow up magnetic resonance diffusion weighted imaging (DWI). Multimodal CT images were reviewed blindly and independently by two stroke neurologists and area under the receiver operating characteristic curve (AUC) was used to compare imaging modalities. From January 2014 to December 2019, 83 patients presented with symptoms suggestive of posterior fossa strokes and had complete imaging suitable for inclusion (49 posterior fossa strokes and 34 DWI negative patients). For posterior fossa strokes, comprehensive CTP analysis had an AUC of 0.68 vs. 0.62 for automated core-penumbra maps and 0.55 for NCCT. For cerebellar lesions >5 mL, the AUC was 0.87, 0.81, and 0.66, respectively. Comprehensive CTP analysis increases the detection of posterior fossa lesions compared to NCCT and should be implemented as part of the routine imaging assessment in posterior fossa strokes.
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http://dx.doi.org/10.3389/fneur.2020.588064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7714905PMC
November 2020

Association of Collateral Status and Ischemic Core Growth in Patients With Acute Ischemic Stroke.

Neurology 2021 01 1;96(2):e161-e170. Epub 2020 Dec 1.

From the Department of Neurology (L.L., J.Y.), Ningbo First Hospital, China; School of Medicine and Public Health (L.L., C.C., H.T., N.J.S., C.R.L., M.W.P.), University of Newcastle; Melbourne Brain Centre at Royal Melbourne Hospital (A.B., M.W.P.), University of Melbourne; and The Sydney Partnership for Health, Education, Research and Enterprise (C.R.L.), Australia.

Objective: To test the hypothesis that patients with acute ischemic stroke with poorer collaterals would have faster ischemic core growth, we included 2 cohorts in the study: cohort 1 of 342 patients for derivation and cohort 2 of 414 patients for validation.

Methods: Patients with acute ischemic stroke with large vessel occlusion were included. Core growth rate was calculated by the following equation: core growth rate = acute core volume on CT perfusion (CTP)/time from stroke onset to CTP. Collateral status was assessed by the ratio of severe hypoperfusion volume within the hypoperfusion region of CTP. The CTP collateral index was categorized in tertiles; for each tertile, core growth rate was summarized as median and interquartile range. Simple linear regressions were then performed to measure the predictive power of CTP collateral index in core growth rate.

Results: For patients allocated to good collateral on CTP (tertile 1 of collateral index), moderate collateral (tertile 2), and poor collateral (tertile 3), the median core growth rate was 2.93 mL/h (1.10-7.94), 8.65 mL/h (4.53-18.13), and 25.41 mL/h (12.83-45.07), respectively. Increments in the collateral index by 1% resulted in an increase of core growth by 0.57 mL/h (coefficient 0.57, 95% confidence interval [0.46, 0.68], < 0.001). The relationship of core growth and CTP collateral index was validated in cohort 2. An increment in collateral index by 1% resulted in an increase of core growth by 0.59 mL/h (coefficient 0.59 [0.48-0.71], < 0.001) in cohort 2.

Conclusion: Collateral status is a major determinant of ischemic core growth.
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http://dx.doi.org/10.1212/WNL.0000000000011258DOI Listing
January 2021

Plasmin Generation Potential and Recanalization in Acute Ischaemic Stroke; an Observational Cohort Study of Stroke Biobank Samples.

Front Neurol 2020 3;11:589628. Epub 2020 Nov 3.

Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia.

More than half of patients who receive thrombolysis for acute ischaemic stroke fail to recanalize. Elucidating biological factors which predict recanalization could identify therapeutic targets for increasing thrombolysis success. We hypothesize that individual patient plasmin potential, as measured by response to recombinant tissue-type plasminogen activator (rt-PA), is a biomarker of rt-PA response, and that patients with greater plasmin response are more likely to recanalize early. This study will use historical samples from the Barcelona Stroke Thrombolysis Biobank, comprised of 350 pre-thrombolysis plasma samples from ischaemic stroke patients who received serial transcranial-Doppler (TCD) measurements before and after thrombolysis. The plasmin potential of each patient will be measured using the level of plasmin-antiplasmin complex (PAP) generated after addition of rt-PA. Levels of antiplasmin, plasminogen, t-PA activity, and PAI-1 activity will also be determined. Association between plasmin potential variables and time to recanalization [assessed on serial TCD using the thrombolysis in brain ischemia (TIBI) score] will be assessed using Cox proportional hazards models, adjusted for potential confounders. The primary outcome will be time to recanalization detected by TCD (defined as TIBI ≥4). Secondary outcomes will be recanalization within 6-h and recanalization and/or haemorrhagic transformation at 24-h. This analysis will utilize an expanded cohort including ~120 patients from the Targeting Optimal Thrombolysis Outcomes (TOTO) study. If association between proteolytic response to rt-PA and recanalization is confirmed, future clinical treatment may customize thrombolytic therapy to maximize outcomes and minimize adverse effects for individual patients.
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http://dx.doi.org/10.3389/fneur.2020.589628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7669985PMC
November 2020

Intravenous alteplase for stroke with unknown time of onset guided by advanced imaging: systematic review and meta-analysis of individual patient data.

Lancet 2020 11 8;396(10262):1574-1584. Epub 2020 Nov 8.

Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany.

Background: Patients who have had a stroke with unknown time of onset have been previously excluded from thrombolysis. We aimed to establish whether intravenous alteplase is safe and effective in such patients when salvageable tissue has been identified with imaging biomarkers.

Methods: We did a systematic review and meta-analysis of individual patient data for trials published before Sept 21, 2020. Randomised trials of intravenous alteplase versus standard of care or placebo in adults with stroke with unknown time of onset with perfusion-diffusion MRI, perfusion CT, or MRI with diffusion weighted imaging-fluid attenuated inversion recovery (DWI-FLAIR) mismatch were eligible. The primary outcome was favourable functional outcome (score of 0-1 on the modified Rankin Scale [mRS]) at 90 days indicating no disability using an unconditional mixed-effect logistic-regression model fitted to estimate the treatment effect. Secondary outcomes were mRS shift towards a better functional outcome and independent outcome (mRS 0-2) at 90 days. Safety outcomes included death, severe disability or death (mRS score 4-6), and symptomatic intracranial haemorrhage. This study is registered with PROSPERO, CRD42020166903.

Findings: Of 249 identified abstracts, four trials met our eligibility criteria for inclusion: WAKE-UP, EXTEND, THAWS, and ECASS-4. The four trials provided individual patient data for 843 individuals, of whom 429 (51%) were assigned to alteplase and 414 (49%) to placebo or standard care. A favourable outcome occurred in 199 (47%) of 420 patients with alteplase and in 160 (39%) of 409 patients among controls (adjusted odds ratio [OR] 1·49 [95% CI 1·10-2·03]; p=0·011), with low heterogeneity across studies (I=27%). Alteplase was associated with a significant shift towards better functional outcome (adjusted common OR 1·38 [95% CI 1·05-1·80]; p=0·019), and a higher odds of independent outcome (adjusted OR 1·50 [1·06-2·12]; p=0·022). In the alteplase group, 90 (21%) patients were severely disabled or died (mRS score 4-6), compared with 102 (25%) patients in the control group (adjusted OR 0·76 [0·52-1·11]; p=0·15). 27 (6%) patients died in the alteplase group and 14 (3%) patients died among controls (adjusted OR 2·06 [1·03-4·09]; p=0·040). The prevalence of symptomatic intracranial haemorrhage was higher in the alteplase group than among controls (11 [3%] vs two [<1%], adjusted OR 5·58 [1·22-25·50]; p=0·024).

Interpretation: In patients who have had a stroke with unknown time of onset with a DWI-FLAIR or perfusion mismatch, intravenous alteplase resulted in better functional outcome at 90 days than placebo or standard care. A net benefit was observed for all functional outcomes despite an increased risk of symptomatic intracranial haemorrhage. Although there were more deaths with alteplase than placebo, there were fewer cases of severe disability or death.

Funding: None.
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http://dx.doi.org/10.1016/S0140-6736(20)32163-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7734592PMC
November 2020

Association of Reperfusion After Thrombolysis With Clinical Outcome Across the 4.5- to 9-Hours and Wake-up Stroke Time Window: A Meta-Analysis of the EXTEND and EPITHET Randomized Clinical Trials.

JAMA Neurol 2021 Feb;78(2):236-240

Department of Medicine and Neurology, Melbourne Brain Centre at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.

Importance: Intravenous alteplase reduces disability after ischemic stroke in patients 4.5 to 9 hours after onset and with wake-up onset stroke selected using perfusion imaging mismatch. However, whether the benefit is consistent across the 4.5- to 6-hours, 6- to 9-hours, and wake-up stroke epochs is uncertain.

Objective: To examine the association of reperfusion with reduced disability, including by onset-to-randomization time strata in the Extending the Time for Thrombolysis in Emergency Neurological Deficits (EXTEND) and Echoplanar Imaging Thrombolytic Evaluation Trial (EPITHET) randomized clinical trials.

Design, Setting, And Participants: Individual patient meta-analysis of randomized clinical trials performed from August 2001 to June 2018 with 3-month follow-up. Patients had acute ischemic stroke with 4.5-to 9-hours poststroke onset or with wake-up stroke were randomized to alteplase or placebo after perfusion mismatch imaging. Analysis began July 2019 and ended May 2020.

Exposures: Reperfusion was defined as more than 90% reduction in time to maximum of more than 6 seconds' lesion volume at 24- to 72-hour follow-up.

Main Outcomes And Measures: Ordinal logistic regression adjusted for baseline age and National Institutes of Health Stroke Scale score was used to analyze functional improvement in day 90 modified Rankin Scale score overall, including a reperfusion × time-to-randomization multiplicative interaction term, and in the 4.5- to 6-hours, 6- to 9-hours, and wake-up time strata. Symptomatic hemorrhage was defined as large parenchymal hematoma with a National Institutes of Health Stroke Scale score increase of 4 points or more.

Results: Reperfusion was assessable in 270 of 295 patients (92%), 68 of 133 (51%) in the alteplase group, and 38 of 137 (28%) in the placebo reperfused group (P < .001). The median (interquartile range) age was 76 (66-81) years in the reperfusion group vs 74 (64.5-81.0) years in the group with no reperfusion. The median (interquartile range) baseline National Institutes of Health Stroke Scale score was 10 (7-15) in the reperfusion group vs 12 (8.0-17.5) in the no reperfusion group. Overall, reperfusion was associated with improved functional outcome (common odds ratio, 7.7; 95% CI, 4.6-12.8; P < .001). Reperfusion was associated with significantly improved functional outcome in each of the 4.5- to 6-hours, 6- to 9-hours, and wake-up time strata, with no evidence of association between time to randomization and beneficial effect of reperfusion (P = .63). Symptomatic hemorrhage, assessed in all 294 patients, occurred in 3 of 51 (5.9%) in the 4.5- to 6-hours group, 2 of 28 (7.1%) in the 6- to 9-hours group, and 4 of 73 (5.5%) in the wake-up stroke in patients treated with alteplase (Fisher P = .91).

Conclusions And Relevance: Strong benefits of reperfusion in all time strata without differential risk in symptomatic hemorrhage support the consistent treatment effect of alteplase in perfusion mismatch-selected patients throughout the 4.5- to 9-hours and wake-up stroke time window.
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http://dx.doi.org/10.1001/jamaneurol.2020.4123DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7607491PMC
February 2021

Tranexamic acid in patients with intracerebral haemorrhage (STOP-AUST): a multicentre, randomised, placebo-controlled, phase 2 trial.

Lancet Neurol 2020 12 28;19(12):980-987. Epub 2020 Oct 28.

Department of Neurology, Royal Adelaide Hospital, Adelaide, SA, Australia.

Background: Despite intracerebral haemorrhage causing 5% of deaths worldwide, few evidence-based therapeutic strategies other than stroke unit care exist. Tranexamic acid decreases haemorrhage in conditions such as acute trauma and menorrhoea. We aimed to assess whether tranexamic acid reduces intracerebral haemorrhage growth in patients with acute intracerebral haemorrhage.

Methods: We did a prospective, double-blind, randomised, placebo-controlled, investigator-led, phase 2 trial at 13 stroke centres in Australia, Finland, and Taiwan. Patients were eligible if they were aged 18 years or older, had an acute intracerebral haemorrhage fulfilling clinical criteria (eg, Glasgow Coma Scale score of >7, intracerebral haemorrhage volume <70 mL, no identified or suspected secondary cause of intracerebral haemorrhage, no thrombotic events within the previous 12 months, no planned surgery in the next 24 h, and no use of anticoagulation), had contrast extravasation on CT angiography (the so-called spot sign), and were treatable within 4·5 h of symptom onset and within 1 h of CT angiography. Patients were randomly assigned (1:1) to receive either 1 g of intravenous tranexamic acid over 10 min followed by 1 g over 8 h or matching placebo, started within 4·5 h of symptom onset. Randomisation was done using a centralised web-based procedure with randomly permuted blocks of varying size. All patients, investigators, and staff involved in patient management were masked to treatment. The primary outcome was intracerebral haemorrhage growth (>33% relative or >6 mL absolute) at 24 h. The primary and safety analyses were done in the intention-to-treat population. The trial is registered at ClinicalTrials.gov (NCT01702636).

Findings: Between March 1, 2013, and Aug 13, 2019, we enrolled and randomly assigned 100 participants to the tranexamic acid group (n=50) or the placebo group (n=50). Median age was 71 years (IQR 57-79) and median intracerebral haemorrhage volume was 14·6 mL (7·9-32·7) at baseline. The primary outcome was not different between the two groups: 26 (52%) patients in the placebo group and 22 (44%) in the tranexamic acid group had intracerebral haemorrhage growth (odds ratio [OR] 0·72 [95% CI 0·32-1·59], p=0·41). There was no evidence of a difference in the proportions of patients who died or had thromboembolic complications between the groups: eight (16%) in the placebo group vs 13 (26%) in the tranexamic acid group died and two (4%) vs one (2%) had thromboembolic complications. None of the deaths was considered related to study medication.

Interpretation: Our study does not provide evidence that tranexamic acid prevents intracerebral haemorrhage growth, although the treatment was safe with no increase in thromboembolic complications. Larger trials of tranexamic acid, with simpler recruitment methods and an earlier treatment window, are justified.

Funding: National Health and Medical Research Council, Royal Melbourne Hospital Foundation.
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http://dx.doi.org/10.1016/S1474-4422(20)30369-0DOI Listing
December 2020

Intensive versus guideline-recommended blood pressure reduction in acute lacunar stroke with intravenous thrombolysis therapy: The ENCHANTED trial.

Eur J Neurol 2021 Mar 1;28(3):783-793. Epub 2020 Dec 1.

The George Institute for Global Health, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.

Background And Purpose: This was an investigation of the differential effects of early intensive versus guideline-recommended blood pressure (BP) lowering between lacunar and non-lacunar acute ischaemic stroke (AIS) in the BP arm of the Enhanced Control of Hypertension and Thrombolysis Stroke Study (ENCHANTED).

Methods: In 1,632 participants classified as having definite or probable lacunar (n = 454 [27.8%]) or non-lacunar AIS according to pre-specified definitions based upon clinical and adjudicated imaging findings, mean BP changes over days 0-7 were plotted, and systolic BP differences by treatment between subgroups were estimated in generalized linear models. Logistic regression models were used to estimate the BP treatment effects on 90-day outcomes (primary, an ordinal shift of modified Rankin scale scores) across lacunar and non-lacunar AIS after adjustment for baseline covariables.

Results: Most baseline characteristics, acute BP and other management differed between lacunar and non-lacunar AIS, but mean systolic BP differences by treatment were comparable at each time point (all p  > 0.12) and over 24 h post-randomization (-5.5, 95% CI -6.5, -4.4 mmHg in lacunar AIS vs. -5.6, 95% CI -6.3, -4.8 mmHg in non-lacunar AIS, p  = 0.93). The neutral effect of intensive BP lowering on functional outcome and the beneficial effect on intracranial haemorrhage were similar for the two subgroups (all p  > 0.19).

Conclusions: There were no differences in the treatment effect of early intensive versus guideline-recommended BP lowering across lacunar and non-lacunar AIS.
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http://dx.doi.org/10.1111/ene.14598DOI Listing
March 2021

Cost-Effectiveness of Tenecteplase Before Thrombectomy for Ischemic Stroke.

Stroke 2020 12 7;51(12):3681-3689. Epub 2020 Oct 7.

Department of Medicine and Neurology, Melbourne Brain Centre at the Royal Melbourne Hospital (L.C., N.Y., B.Y., M.W.P., G.A.D., S.M.D., B.C.V.C.), University of Melbourne, Parkville, Australia.

Background And Purpose: Tenecteplase improved functional outcomes and reduced the requirement for endovascular thrombectomy in ischemic stroke patients with large vessel occlusion in the EXTEND-IA TNK randomized trial. We assessed the cost-effectiveness of tenecteplase versus alteplase in this trial.

Methods: Post hoc within-trial economic analysis included costs of index emergency department and inpatient stroke hospitalization, rehabilitation/subacute care, and rehospitalization due to stroke within 90 days. Sources for cost included key study site complemented by published literature and government websites. Quality-adjusted life-years were estimated using utility scores derived from the modified Rankin Scale score at 90 days. Long-term modeled cost-effectiveness analysis used a Markov model with 7 health states corresponding to 7 modified Rankin Scale scores. Probabilistic sensitivity analyses were performed.

Results: Within the 202 patients in the randomized controlled trial, total cost was nonsignificantly lower in the tenecteplase-treated patients (40 997 Australian dollars [AUD]) compared with alteplase-treated patients (46 188 AUD) for the first 90 days(=0.125). Tenecteplase was the dominant treatment strategy in the short term, with similar cost (5412 AUD [95% CI, -13 348 to 2523]; =0.181) and higher benefits (0.099 quality-adjusted life-years [95% CI, 0.001-0.1967]; =0.048), with a 97.4% probability of being cost-effective. In the long-term, tenecteplase was associated with less additional lifetime cost (96 357 versus 106 304 AUD) and greater benefits (quality-adjusted life-years, 7.77 versus 6.48), and had a 100% probability of being cost-effective. Both deterministic sensitivity analysis and probabilistic sensitivity analyses yielded similar results.

Conclusions: Both within-trial and long-term economic analyses showed that tenecteplase was highly likely to be cost-effective for patients with acute stroke before thrombectomy. Recommending the use of tenecteplase over alteplase could lead to a cost saving to the healthcare system both in the short and long term. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02388061.
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http://dx.doi.org/10.1161/STROKEAHA.120.029666DOI Listing
December 2020

Intraarterial Versus Intravenous Tirofiban as an Adjunct to Endovascular Thrombectomy for Acute Ischemic Stroke.

Stroke 2020 10 16;51(10):2925-2933. Epub 2020 Sep 16.

School of Medicine and Public Health, University of Newcastle, Australia (C.R.L., M.W.P., L.L.).

Background And Purpose: This study aimed to evaluate the treatment effect of intraarterial versus intravenous tirofiban during endovascular thrombectomy in acute ischemic stroke.

Methods: This study retrospectively examined 503 patients with acute ischemic stroke with large vessel occlusion who received endovascular thrombectomy within 24 hours of stroke onset. Patients were divided into 3 groups: no tirofiban (n=354), intraarterial tirofiban (n=79), and intravenous tirofiban (n=70). The 3 groups were compared in terms of recanalization rate, symptomatic intracerebral hemorrhage, in-hospital death rate, 3-month death, and 3-month outcomes measured by modified Rankin Scale score (good clinical outcome of 0-2, poor outcome of 5-6). The comparison was statistically assessed by propensity score matching, followed by Freidman rank-sum test and pairwise Wilcoxon signed-rank test with Bonferroni correction.

Results: The propensity score matching resulted in 92 matched triplets. Compared with the no-tirofiban group, the intravenous tirofiban group showed significantly increased recanalization (96.7% versus 64.1%, <0.001), an increased rate of 3-month good outcome (69.5% versus 51.2%, =0.034), and a lower rate of 3-month poor outcome (12.2% versus 41.4%, <0.001). There was no significant difference between the tirofiban intravenous and no-tirofiban groups in terms of symptomatic intracerebral hemorrhage (2.2% versus 0%, =1.000). However, symptomatic intracerebral hemorrhage was significantly increased in the intraarterial-tirofiban group compared with the no-tirofiban group (19.1% versus 0%, <0.001), with an increased rate of in-hospital death (23.6% versus 0% <0.001), and increased rate of 3-month death (26.8% versus 11.1%, =0.021). The intraarterial-tirofiban and no-tirofiban group showed no significant difference in recanalization rate (66.3% versus 64.1%, =1.000).

Conclusions: As an adjunct to endovascular thrombectomy, intravenous tirofiban is associated with high recanalization rate and good outcome, whereas intraarterial tirofiban is associated with high hemorrhagic rate and death rate.
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http://dx.doi.org/10.1161/STROKEAHA.120.029994DOI Listing
October 2020

Air vs. Road Decision for Endovascular Clot Retrieval in a Rural Telestroke Network.

Front Neurol 2020 17;11:628. Epub 2020 Jul 17.

Department of Neurology, John Hunter Hospital, University of Newcastle, Newcastle, NSW, Australia.

Telestroke aims to increase access to endovascular clot retrieval (ECR) for rural areas. There is limited information on transfer workflow for ECR in rural settings. We sought to describe the transfer metrics for ECR in a rural telestroke network with respect to decision making. A retrospective cohort study was employed on consecutive patients transferred to the comprehensive stroke center (CSC) for ECR in a rural hub-and-spoke telestroke network between April 2013 and October 2019, by road or air. Key time-based metrics were analyzed. Sixty-two patients were included. Mean age was 66 years [standard deviation (SD), 14] and median National Institutes of Health Stroke Scale 13 [interquartile range (IQR), 8-18]. Median rural-hospital-door-to-CSC-door (D2D) was 308 min (IQR, 254-351), of which 68% was spent at rural hospitals [door-in-door-out (DIDO); 214 min; IQR, 171-247]. DIDO was longer for air transfers than road ( = 0.004), primarily because of a median 87 min greater decision-to-departure time (Decision-DO, < 0.001). In multiple linear regression analysis, intubation but not thrombolysis was associated with significantly longer DIDO. The distance at which the extra speed of an aircraft made up for the delays involved in booking an aircraft was 299 km from the CSC. DIDO is longer for air retrievals compared with road. Decision-DO represents the most important component of DIDO, being longer for air transfers. Systems for rapid transportation of rural ECR candidates need optimization for best patient outcomes, with decision support seen as a potential tool to achieve this.
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http://dx.doi.org/10.3389/fneur.2020.00628DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7380106PMC
July 2020

Thrombolysis Outcomes in Acute Ischemic Stroke by Fluid-Attenuated Inversion Recovery Hyperintense Arteries.

Stroke 2020 07 17;51(7):2240-2243. Epub 2020 Jun 17.

The George Institute for Global Health, Faculty of Medicine, University of New South Wales Sydney, Australia (Z.Z., S.Y., C.D., A.M., T.T.-Y., C.C., X.W., X.C., J.C., C.S.A.).

Background And Purpose: To determine factors associated with fluid-attenuated inversion recovery (FLAIR) hyperintense arteries (FLAIR-HAs) on magnetic resonance imaging and their prognostic significance in thrombolysis-treated patients with acute ischemic stroke from the ENCHANTED (Enhanced Control of Hypertension and Thrombolysis Stroke Study) trial alteplase-dose arm.

Methods: Patients with acute ischemic stroke (N=293) with brain magnetic resonance imaging (FLAIR and diffusion-weighted imaging sequences) scanned <4.5 hours of symptom onset were assessed for location and extent (score) of FLAIR-HAs, infarct volume, large vessel occlusion (LVO), and other ischemic signs. Logistic regression models were used to determine predictors of FLAIR-HAs and the association of FLAIR-HAs with 90-day outcomes: favorable functional outcome (primary; modified Rankin Scale scores, 0-1), other modified Rankin Scale scores, and intracerebral hemorrhage.

Results: Prior atrial fibrillation, LVO, large infarct volume, and anterior circulation infarction were independently associated with FLAIR-HAs. The rate of modified Rankin Scale scores 0 to 1 was numerically lower in patients with FLAIR-HAs versus without (69/152 [45.4%] versus 75/131 [57.3%]), as was the subset of LVO (37/93 [39.8%] versus 9/16 [56.3%]), but not in those without LVO (25/36 [69.4%] versus 60/106 [56.6%]). After adjustment for covariables, FLAIR-HAs were independently associated with increased primary outcome (adjusted odds ratio [95% CI]: overall 4.14 [1.63-10.50]; with LVO 4.92 [0.87-27.86]; no LVO 6.16 [1.57-24.14]) despite an increased risk of hemorrhagic infarct (4.77 [1.12-20.26]).

Conclusions: FLAIR-HAs are more frequent in acute ischemic stroke with cardioembolic features and indicate potential for a favorable prognosis in thrombolysis-treated patients possibly mediated by LVO. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01422616.
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July 2020

Economic evaluation of the Melbourne Mobile Stroke Unit.

Int J Stroke 2020 Jun 14:1747493020929944. Epub 2020 Jun 14.

Stroke & Ageing Research, Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Clayton, VIC, Australia.

Background: The Melbourne Mobile Stroke Unit (MSU) is the first Australian service to provide prehospital acute stroke treatment, including thrombolysis and facilitated triage for endovascular thrombectomy.

Aims: To estimate the cost-effectiveness of the MSU during the first full year of operation compared with standard ambulance and hospital stroke care pathways (standard care).

Methods: The costs and benefits of the Melbourne MSU were estimated using an economic simulation model. Operational costs and service utilization data were obtained from the MSU financial and patient tracking reports. The health benefits were estimated as disability-adjusted life years (DALYs) avoided using local data on reperfusion therapy and estimates from the published literature on their effectiveness. Costs were presented in Australian dollars. The robustness of results was assessed using multivariable (model inputs varied simultaneously: 10,000 Monte Carlo iterations) and various one-way sensitivity analyses.

Results: In 2018, the MSU was dispatched to 1244 patients during 200 days of operation. Overall, 167 patients were diagnosed with acute ischemic stroke, and 58 received thrombolysis, endovascular thrombectomy, or both. We estimated 27.94 DALYs avoided with earlier access to endovascular thrombectomy (95% confidence interval (CI) 15.30 to 35.93) and 16.90 DALYs avoided with improvements in access to thrombolysis (95% CI 9.05 to 24.68). The MSU was estimated to cost an additional $30,982 per DALY avoided (95% CI $21,142 to $47,517) compared to standard care.

Conclusions: There is evidence that the introduction of MSU is cost-effective when compared with standard care due to earlier provision of reperfusion therapies.
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http://dx.doi.org/10.1177/1747493020929944DOI Listing
June 2020

Developing a multivariable prediction model for functional outcome after reperfusion therapy for acute ischaemic stroke: study protocol for the Targeting Optimal Thrombolysis Outcomes (TOTO) multicentre cohort study.

BMJ Open 2020 04 6;10(4):e038180. Epub 2020 Apr 6.

The Sydney Partnership for Health, Education, Research & Enterprise (SPHERE), Sydney, New South Wales, Australia.

Introduction: Intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator (rt-PA) is the only approved pharmacological reperfusion therapy for acute ischaemic stroke. Despite population benefit, IVT is not equally effective in all patients, nor is it without significant risk. Uncertain treatment outcome prediction complicates patient treatment selection. This study will develop and validate predictive algorithms for IVT response, using clinical, radiological and blood-based biomarker measures. A secondary objective is to develop predictive algorithms for endovascular thrombectomy (EVT), which has been proven as an effective reperfusion therapy since study inception.

Methods And Analysis: The Targeting Optimal Thrombolysis Outcomes Study is a multicenter prospective cohort study of ischaemic stroke patients treated at participating Australian Stroke Centres with IVT and/or EVT. Patients undergo neuroimaging using multimodal CT or MRI at baseline with repeat neuroimaging 24 hours post-treatment. Baseline and follow-up blood samples are provided for research use. The primary outcome is good functional outcome at 90 days poststroke, defined as a modified Rankin Scale (mRS) Score of 0-2. Secondary outcomes are reperfusion, recanalisation, infarct core growth, change in stroke severity, poor functional outcome, excellent functional outcome and ordinal mRS at 90 days. Primary predictive models will be developed and validated in patients treated only with rt-PA. Models will be built using regression methods and include clinical variables, radiological measures from multimodal neuroimaging and blood-based biomarkers measured by mass spectrometry. Predictive accuracy will be quantified using c-statistics and R. In secondary analyses, models will be developed in patients treated using EVT, with or without prior IVT, reflecting practice changes since original study design.

Ethics And Dissemination: Patients, or relatives when patients could not consent, provide written informed consent to participate. This study received approval from the Hunter New England Local Health District Human Research Ethics Committee (reference 14/10/15/4.02). Findings will be disseminated via peer-reviewed publications and conference presentations.
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http://dx.doi.org/10.1136/bmjopen-2020-038180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7245375PMC
April 2020

Dabigatran Reversal Before Intravenous Tenecteplase in Acute Ischemic Stroke.

Stroke 2020 05 25;51(5):1616-1619. Epub 2020 Mar 25.

From the Department of Neurology, Christchurch Hospital, New Zealand (J.B., J.N.F., D.W., T.Y.W.).

Background and Purpose- Reversal of dabigatran before intravenous thrombolysis in patients with acute ischemic stroke has been well described using alteplase but experience with intravenous tenecteplase is limited. Tenecteplase seems at least noninferior to alteplase in patients with intracranial large vessel occlusion. We report on the experience of dabigatran reversal before tenecteplase thrombolysis for acute ischemic stroke. Methods- We included consecutive patients with ischemic stroke receiving dabigatran prestroke treated with intravenous tenecteplase after receiving idarucizumab. Patients were from 2 centers in New Zealand and Australia. We reported the clinical, laboratory, and radiological characteristics and their functional outcome. Results- We identified 13 patients receiving intravenous tenecteplase after dabigatran reversal. Nine (69%) were male, median age was 79 (interquartile range, 69-85) and median baseline National Institutes of Health Stroke Scale score was 6 (interquartile range, 4-21). Atrial fibrillation was the indication for dabigatran therapy in all patients. All patients had a prolonged thrombin clotting time (median, 80 seconds [interquartile range, 57-113]). Seven patients with large vessel occlusion were referred for endovascular thrombectomy, 2 of these patients (29%) had early recanalization with tenecteplase abrogating thrombectomy. No patients had parenchymal hemorrhage or symptomatic hemorrhagic transformation. Favorable functional outcome (modified Rankin Scale score, 0-2) occurred in 8 (62%) patients. Two deaths occurred from large territory infarction. Conclusions- Our experience suggests intravenous thrombolysis with tenecteplase following dabigatran reversal using idarucizumab may be safe in selected patients with acute ischemic stroke. Further studies are required to more precisely estimate the efficacy and risk of clinically significant hemorrhage.
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http://dx.doi.org/10.1161/STROKEAHA.119.028327DOI Listing
May 2020

Effect of Intravenous Tenecteplase Dose on Cerebral Reperfusion Before Thrombectomy in Patients With Large Vessel Occlusion Ischemic Stroke: The EXTEND-IA TNK Part 2 Randomized Clinical Trial.

JAMA 2020 04;323(13):1257-1265

Department of Medicine, Ballarat Base Hospital, Ballarat, Victoria, Australia.

Importance: Intravenous thrombolysis with tenecteplase improves reperfusion prior to endovascular thrombectomy for ischemic stroke compared with alteplase.

Objective: To determine whether 0.40 mg/kg of tenecteplase safely improves reperfusion before endovascular thrombectomy vs 0.25 mg/kg of tenecteplase in patients with large vessel occlusion ischemic stroke.

Design, Setting, And Participants: Randomized clinical trial at 27 hospitals in Australia and 1 in New Zealand using open-label treatment and blinded assessment of radiological and clinical outcomes. Patients were enrolled from December 2017 to July 2019 with follow-up until October 2019. Adult patients (N = 300) with ischemic stroke due to occlusion of the intracranial internal carotid, \basilar, or middle cerebral artery were included less than 4.5 hours after symptom onset using standard intravenous thrombolysis eligibility criteria.

Interventions: Open-label tenecteplase at 0.40 mg/kg (maximum, 40 mg; n = 150) or 0.25 mg/kg (maximum, 25 mg; n = 150) given as a bolus before endovascular thrombectomy.

Main Outcomes And Measures: The primary outcome was reperfusion of greater than 50% of the involved ischemic territory prior to thrombectomy, assessed by consensus of 2 blinded neuroradiologists. Prespecified secondary outcomes were level of disability at day 90 (modified Rankin Scale [mRS] score; range, 0-6); mRS score of 0 to 1 (freedom from disability) or no change from baseline at 90 days; mRS score of 0 to 2 (functional independence) or no change from baseline at 90 days; substantial neurological improvement at 3 days; symptomatic intracranial hemorrhage within 36 hours; and all-cause death.

Results: All 300 patients who were randomized (mean age, 72.7 years; 141 [47%] women) completed the trial. The number of participants with greater than 50% reperfusion of the previously occluded vascular territory was 29 of 150 (19.3%) in the 0.40 mg/kg group vs 29 of 150 (19.3%) in the 0.25 mg/kg group (unadjusted risk difference, 0.0% [95% CI, -8.9% to -8.9%]; adjusted risk ratio, 1.03 [95% CI, 0.66-1.61]; P = .89). Among the 6 secondary outcomes, there were no significant differences in any of the 4 functional outcomes between the 0.40 mg/kg and 0.25 mg/kg groups nor in all-cause deaths (26 [17%] vs 22 [15%]; unadjusted risk difference, 2.7% [95% CI, -5.6% to 11.0%]) or symptomatic intracranial hemorrhage (7 [4.7%] vs 2 [1.3%]; unadjusted risk difference, 3.3% [95% CI, -0.5% to 7.2%]).

Conclusions And Relevance: Among patients with large vessel occlusion ischemic stroke, a dose of 0.40 mg/kg, compared with 0.25 mg/kg, of tenecteplase did not significantly improve cerebral reperfusion prior to endovascular thrombectomy. The findings suggest that the 0.40-mg/kg dose of tenecteplase does not confer an advantage over the 0.25-mg/kg dose in patients with large vessel occlusion ischemic stroke in whom endovascular thrombectomy is planned.

Trial Registration: ClinicalTrials.gov Identifier: NCT03340493.
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http://dx.doi.org/10.1001/jama.2020.1511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7139271PMC
April 2020

Melbourne Mobile Stroke Unit and Reperfusion Therapy: Greater Clinical Impact of Thrombectomy Than Thrombolysis.

Stroke 2020 03 12;51(3):922-930. Epub 2020 Feb 12.

From the Department of Neurology, Melbourne Brain Centre (H.Z., S.C., D.E., L.C., N.Y., B.Y., B.C.V.C., M.W.P., G.A.D., S.M.D.), Royal Melbourne Hospital, Victoria, Australia.

Background and Purpose- Mobile stroke units (MSUs) are increasingly used worldwide to provide prehospital triage and treatment. The benefits of MSUs in giving earlier thrombolysis have been well established, but the impacts of MSUs on endovascular thrombectomy (EVT) and effect on disability avoidance are largely unknown. We aimed to determine the clinical impact and disability reduction for reperfusion therapies in the first operational year of the Melbourne MSU. Methods- Treatment time metrics for MSU patients receiving reperfusion therapy were compared with control patients presenting to metropolitan Melbourne stroke units via standard ambulance within MSU operating hours. The primary outcome was median time difference in first ambulance dispatch to treatment modeled using quantile regression analysis. Time savings were subsequently converted to disability-adjusted life years avoided using published estimates. Results- In the first 365-day operation of the Melbourne MSU, prehospital thrombolysis was administered to 100 patients (mean age, 73.8 years; 62% men). The median time savings per MSU patient, compared with the control cohort, was 26 minutes (<0.001) for dispatch to hospital arrival and 15 minutes (<0.001) for hospital arrival to thrombolysis. The calculated overall time saving from dispatch to thrombolysis was 42.5 minutes (95% CI, 36.0-49.0). In the same period, 41 MSU patients received EVT (mean age, 76 years; 61% men) with median dispatch-to-treatment time saving of 51 minutes ([95% CI, 30.1-71.9], <0.001). This included a median time saving of 17 minutes ([95% CI, 7.6-26.4], =0.001) for EVT hospital arrival to arterial puncture for MSU patients. Estimated median disability-adjusted life years saved through earlier provision of reperfusion therapies were 20.9 for thrombolysis and 24.6 for EVT. Conclusions- The Melbourne MSU substantially reduced time to reperfusion therapies, with the greatest estimated disability avoidance driven by the more powerful impact of earlier EVT. These findings highlight the benefits of prehospital notification and direct triage to EVT centers with facilitated workflow on arrival by the MSU.
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http://dx.doi.org/10.1161/STROKEAHA.119.027843DOI Listing
March 2020

Cluster-Randomized Trial of Thrombolysis Implementation Support in Metropolitan and Regional Australian Stroke Centers: Lessons for Individual and Systems Behavior Change.

J Am Heart Assoc 2020 02 24;9(3):e012732. Epub 2020 Jan 24.

The University of Newcastle, School of Medicine and Public Health Callaghan Australia.

Background Intravenous thrombolytic therapy (IVT) with tissue plasminogen activator for acute ischemic stroke is underutilized in many parts of the world. Randomized trials to test the effectiveness of thrombolysis implementation strategies are limited. Methods and Results This study aimed to test the effectiveness of a multicomponent, multidisciplinary tissue plasminogen activator implementation package in increasing the proportion of thrombolyzed cases while maintaining accepted benchmarks for low rates of intracranial hemorrhage and high rates of functional outcomes at 3 months. A cluster randomized controlled trial of 20 hospitals in the early stages of thrombolysis implementation across 3 Australian states was undertaken. Monitoring of IVT rates during the baseline period allowed hospitals (the unit of randomization) to be grouped into 3 baseline IVT strata-very low rates (0% to ≤4.0%); low rates (>4.0% to ≤10.0%); and moderate rates (>10.0%). Hospitals were randomized to an implementation package (experimental group) or usual care (control group) using a 1:1 ratio. The 16-month intervention was based on behavioral theory and analysis of the steps, roles, and barriers to rapid assessment for thrombolysis eligibility and involved comprehensive strategies addressing individual and system-level change. The primary outcome was the difference in tissue plasminogen activator proportions between the 2 groups postintervention. The absolute difference in postintervention IVT rates between intervention and control hospitals adjusted for baseline IVT rate and stratum was not significant (primary outcome rate difference=1.1% (95% CI -1.5% to 3.7%; =0.38). Rates of intracranial hemorrhage remained below international benchmarks. Conclusions The implementation package resulted in no significant change in tissue plasminogen activator implementation, suggesting that ongoing support is needed to sustain initial modifications in behavior. Clinical Trial Registration URL: www.anzctr.org.au Unique identifiers: ACTRN12613000939796 and U1111-1145-6762.
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http://dx.doi.org/10.1161/JAHA.119.012732DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033885PMC
February 2020

Perfusion Computed Tomography Accurately Quantifies Collateral Flow After Acute Ischemic Stroke.

Stroke 2020 03 17;51(3):1006-1009. Epub 2020 Jan 17.

From the School of Medicine and Public Health (L.L., C.C., H.T., N.S., C.R.L., M.W.P.), University of Newcastle, Australia.

Background and Purpose- This study aimed to derive and validate an optimal collateral measurement on computed tomographic perfusion imaging for patients with acute ischemic stroke. Methods- In step 1 analysis of 22 patients, the parasagittal region of the ischemic hemisphere was divided into 6 pial arterial zones to derive the optimal collateral threshold by receiver operating characteristic analysis. The collateral threshold was then used to define the collateral index in step 2. In step 2 analysis of 156 patients, the computed tomographic perfusion collateral index was compared with collateral scores on dynamic computed tomographic angiography in predicting good clinical outcome by simple regression. Results- The optimal collateral threshold was delay time >6 s (sensitivity, 88%; specificity, 92%). The computed tomographic perfusion collateral index, defined by the ratio of delay time >6 s/delay time >2 s volume, showed a significant correlation with dynamic computed tomographic angiography collateral scores (correlation coefficient, 0.62; <0.001), with an optimal cut point of 31.8% in predicting good collateral status (sensitivity of 83% and specificity of 86%). When predicting good clinical outcome, the delay time collateral index showed a similar predictive power to dynamic computed tomographic angiography collaterals (area under the curve, 0.78 [0.67-0.83] and 0.77 [0.69-0.84], respectively; <0.001). Conclusions- Computed tomographic perfusion can accurately quantify collateral flow after acute ischemic stroke.
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http://dx.doi.org/10.1161/STROKEAHA.119.028284DOI Listing
March 2020

Computed Tomography Perfusion Identifies Patients With Stroke With Impaired Cardiac Function.

Stroke 2020 02 3;51(2):498-503. Epub 2020 Jan 3.

Hunter Medical Research Institute (C.G.-E., N.J.S., F.M., T.L., S.T., C.R.L., M.W.P.), University of Newcastle, Australia.

Background and Purpose- Low left ventricular ejection fraction (LVEF) leads to worse outcomes after stroke. We hypothesized that the arterial input function (AIF) variability on perfusion computed tomography, especially the time between scan onset and end of AIF (SO-EndAIF), would reflect reduction of cardiac output. Methods- Retrospective analysis of consecutive stroke patients, who underwent computed tomography between January 2013 and September 2018, was performed in 2 parts. (1) To determine the correlation between SO-EndAIF and LVEF, all patients with a transthoracic echocardiogram performed ±6 months from the time of stroke were included. LVEF was dichotomized as either normal (≥50%) or decreased (<50%). (2) AIF was compared with hypoperfusion volume, defined as delay time >3 seconds and with clinical outcome measured using 3-month modified Rankin Scale. Results- A total of 732 ischemic stroke patients underwent computed tomography, 231 with transthoracic echocardiogram were included in part (1), 393 with outcome data were included in part (2). In part (1), 193/231 (83.5%) had normal LVEF (median 61%) and 38/231 (16.5%) decreased LVEF (median 39%). The low-LVEF group had significantly prolonged SO-EndAIF compared with normal-LVEF group (mean of 39.7 versus 26 second; <0.001), and larger hypoperfusion lesions (94.9 versus 37.6 mL; <0.001). SO-EndAIF time was strongly associated with EF, with an area under the curve of 0.86. Twenty nine seconds was the best threshold to distinguish between normal and impaired EF (area under the curve, 0.77). In part (2), the SO-EndAIF ≥29 second group had larger hypoperfusion volumes (21.8 versus 89.7 mL; <0.001) and infarct core (12.2 versus 2.3 mL; <0.0001) and patients with SO-EndAIF ≥29 seconds had fewer excellent or good clinical outcomes (modified Rankin Scale score 0-1; 40% versus 22%; OR, 2.79; <0.001, modified Rankin Scale score 0-2; 65% versus 35%; OR, 1.41; =0.033). Conclusions- AIF width correlates with ejection fraction in acute ischemic stroke. A 29-second threshold from scan onset to end of AIF accurately predicts reduced LVEF and identifies patients more likely to have worse outcomes after stroke.
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http://dx.doi.org/10.1161/STROKEAHA.119.027255DOI Listing
February 2020

Dynamic CT but Not Optimized Multiphase CT Angiography Accurately Identifies CT Perfusion Target Mismatch Ischemic Stroke Patients.

Front Neurol 2019 23;10:1130. Epub 2019 Oct 23.

Department of Neurology, The Royal Melbourne Hospital, University of Melbourne, Melbourne, VIC, Australia.

Imaging protocols for acute ischemic stroke varies significantly from center to center leading to challenges in research translation. We aimed to assess the inter-rater reliability of collateral grading systems derived from dynamic computed tomography angiography (CTA) and an optimized multiphase CTA and, to analyze the association of the two CTA modalities with CT perfusion (CTP) compartments by comparing the accuracy of dynamic CTA (dCTA) and optimized multiphase CTA (omCTA) in identifying CT perfusion (CTP) target mismatch patients. Acute ischemic stroke patients with a proximal large vessel occlusion who underwent whole brain CTP were included in the study. Collateral status were assessed using ASPECTS collaterals (Alberta Stroke Program Early CT Score on Collaterals) and ASITN/SIR collateral system (the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology) on dCTA and omCTA. Eighty-one patients were assessed, with a median ischemic core volume of 29 mL. The collateral assessment with ASPECTS collaterals using dCTA have a similar inter-rater agreement (K-alpha: 0.71) compared to omCTA (K-alpha: 0.69). However, the agreement between dCTA and CTP in classifying patients with target mismatch was higher compared to omCTA (Kappa, dCTA: 0.81; omCTA: 0.64). We found dCTA was more accurate than omCTA in identifying target mismatch patients with proximal large vessel occlusion.
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http://dx.doi.org/10.3389/fneur.2019.01130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6819495PMC
October 2019

Comparing mismatch strategies for patients being considered for ischemic stroke tenecteplase trials.

Int J Stroke 2020 Jul 4;15(5):507-515. Epub 2019 Nov 4.

Department of Medicine and Neurology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia.

Background: Currently there are multiple variations of imaging-based patient selection mismatch methods in ischemic stroke. In the present study, we sought to compare the two most common mismatch methods and identify if there were different effects on the outcome of a randomized clinical trial depending on the mismatch method used.

Aims: Investigate the effect of clinical and imaging-based mismatch criteria on patient outcomes of a pooled cohort from randomized trials of intravenous tenecteplase versus alteplase.

Methods: Baseline clinical and imaging scores were used to categorize patients as meeting either the DAWN mismatch (baseline NIHSS ≥ 10, and age cut-offs for ischemic core volume) or DEFUSE 2 mismatch criteria (mismatch volume > 15 mL, mismatch ratio > 1.8 and ischemic core < 70 mL). We then investigated whether tenecteplase-treated patients had favorable odds of less disability (on modified Rankin scale, mRS) compared to those treated with alteplase, for clinical and imaging mismatch, respectively.

Results: From 146 pooled patients, 71 received alteplase and 75 received tenecteplase. The overall pooled group did not show improved patient outcomes when treated with tenecteplase (mRS 0-1 OR 1.77, 95% CI 0.89-3.51,  = 0.102) compared with alteplase. A total of 39 (27%) patients met both clinical and imaging mismatch criteria, 25 (17%) patients met only imaging criteria, 36 (25%) met only clinical mismatch criteria and, finally, 46 (31%) did not meet either of imaging or mismatch criteria. Patients treated with tenecteplase had more favorable outcomes when they met either imaging mismatch (mRS 0-1, OR 2.33, 95% CI 1.13-5.94,  = 0.032) or clinical mismatch criteria (mRS 0-1, OR 2.15, 95% CI 1.142, 8.732,  = 0.027) but with differing proportions.

Conclusion: Target mismatch selection was more inclusive and exhibited in a larger treatment effect between tenecteplase and alteplase.
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http://dx.doi.org/10.1177/1747493019884529DOI Listing
July 2020