Fiona Catherine Moreton

Alteplase versus tenecteplase for thrombolysis after ischaemic stroke (ATTEST): a phase 2, randomised, open-label, blinded endpoint study.

BACKGROUND In most countries, alteplase given within 4·5 h of onset is the only approved medical treatment for acute ischaemic stroke. The newer thrombolytic drug tenecteplase has been investigated in one randomised trial up to 3 h after stroke and in another trial up to 6 h after stroke in patients selected by advanced neuroimaging. In the Alteplase-Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST), we aimed to assess the efficacy and safety of tenecteplase versus alteplase within 4·5 h of stroke onset in a population not selected on the basis of advanced neuroimaging, and to use imaging biomarkers to inform the design of a definitive phase 3 clinical trial. METHODS In this single-centre, phase 2, prospective, randomised, open-label, blinded end-point evaluation study, adults with supratentorial ischaemic stroke eligible for intravenous thrombolysis within 4·5 h of onset were recruited from The Institute of Neurological Sciences, Glasgow, Scotland. Patients were randomly assigned (1:1) to receive tenecteplase 0·25 mg/kg (maximum 25 mg) or alteplase 0·9 mg/kg (maximum 90 mg). Treatment allocation used a mixed randomisation and minimisation algorithm including age and National Institutes of Health Stroke Scale score, generated by an independent statistician. Patients were not informed of treatment allocation; treating clinicians were aware of allocation but those assessing the primary outcome were not. Imaging comprised baseline CT, CT perfusion, and CT angiography; and CT plus CT angiography at 24-48 h. The primary endpoint was percentage of penumbra salvaged (CT perfusion-defined penumbra volume at baseline minus CT infarct volume at 24-48 h). Analysis was per protocol. This study is registered with ClinicalTrials.gov, number NCT01472926. FINDINGS Between Jan 1, 2012, and Sept 7, 2013, 355 patients were screened, of whom 157 were eligible for intravenous thrombolysis, and 104 patients were enrolled. 52 were assigned to the alteplase group and 52 to tenecteplase. Of 71 patients (35 assigned tenecteplase and 36 assigned alteplase) contributing to the primary endpoint, no significant differences were noted for percentage of penumbral salvaged (68% [SD 28] for the tenecteplase group vs 68% [23] for the alteplase group; mean difference 1·3% [95% CI -9·6 to 12·1]; p=0·81). Neither incidence of symptomatic intracerebral haemorrhage (by SITS-MOST definition, 1/52 [2%] tenecteplase vs 2/51 [4%] alteplase, p=0·55; by ECASS II definition, 3/52 [6%] vs 4/51 [8%], p=0·59) nor total intracerebral haemorrhage events (8/52 [15%] vs 14/51 [29%], p=0·091) differed significantly. The incidence of serious adverse events did not differ between groups (32 in the tenecteplase group, three considered probably or definitely related to drug treatment; 16 in the alteplase group, five were considered drug-related). INTERPRETATION Neurological and radiological outcomes did not differ between the tenecteplase and alteplase groups. Evaluation of tenecteplase in larger trials of patients with acute stroke seems warranted. FUNDING The Stroke Association.

Cerebral small vessel disease: Capillary pathways to stroke and cognitive decline

Cerebral small vessel disease (SVD) gives rise to one in five strokes worldwide and constitutes a major source of cognitive decline in the elderly. SVD is known to occur in relation to hypertension, diabetes, smoking, radiation therapy and in a range of inherited and genetic disorders, autoimmune disorders, connective tissue disorders, and infections. Until recently, changes in capillary patency and blood viscosity have received little attention in the aetiopathogenesis of SVD and the high risk of subsequent stroke and cognitive decline. Capillary flow patterns were, however, recently shown to limit the extraction efficacy of oxygen in tissue and capillary dysfunction therefore proposed as a source of stroke-like symptoms and neurodegeneration, even in the absence of physical flow-limiting vascular pathology. In this review, we examine whether capillary flow disturbances may be a shared feature of conditions that represent risk factors for SVD. We then discuss aspects of capillary dysfunction that could be prevented or alleviated and therefore might be of general benefit to patients at risk of SVD, stroke or cognitive decline.

Changing clinical patterns and increasing prevalence in CADASIL

CADASIL is a monogenic small vessel vasculopathy causing recurrent stroke. Early descriptions suggested dementia and disability were common from the 5th decade but there is evidence of marked phenotypic variability. We investigated the prevalence and clinical features of CADASIL in the west of Scotland.

Insular Cortex Hypoperfusion and Acute Phase Blood Glucose After Stroke A CT Perfusion Study

Background and Purpose— Insular cortex ischemia is proposed to mediate a sympathetic stimulus that leads to acute hyperglycemia after stroke. Methods— We retrospectively analyzed insular perfusion on perfusion CT (median 180 minutes after onset) in 35 patients. Results— We found no association of hypoperfusion (relative cerebral blood flow <0.51) with early (<6 hours) or delayed (<72 hours) hyperglycemia, or hemispheric lateralization. Conclusions— Insular cortex hypoperfusion <6 hours after stroke onset was not associated with hyperglycemia.

Cysteine-Sparing CADASIL Mutations in NOTCH3 Show Proaggregatory Properties In Vitro

Background and Purpose— Mutations in NOTCH3 cause cerebral autosomal–dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the most common monogenic cause of stroke and vascular dementia. Misfolding and aggregation of NOTCH3 proteins triggered by cysteine-affecting mutations are considered to be the key disease mechanisms. However, the significance of cysteine-sparing mutations is still debated. Methods— We studied a family with inherited small vessel disease by standardized medical history, clinical examination, MRI, ultrastructural analysis of skin biopsies, and Sanger sequencing of all NOTCH3 exons. In addition, we performed in vitro characterization of NOTCH3 variants using recombinant protein fragments and a single-particle aggregation assay. Results— We identified a novel cysteine-sparing NOTCH3 mutation (D80G) in 4 family members, which was absent in a healthy sibling. All mutation carriers exhibited a CADASIL typical brain imaging and clinical phenotype, whereas skin biopsy showed inconsistent results. In vitro aggregation behavior of the D80G mutant was similar compared with cysteine-affecting mutations. This was reproduced with cysteine-sparing mutations from previously reported families having a phenotype consistent with CADASIL. Conclusions— Our findings support the view that cysteine-sparing mutations, such as D80G, might cause CADASIL with a phenotype largely indistinguishable from cysteine mutations. The in vitro aggregation analysis of atypical NOTCH3 mutations offers novel insights into pathomechanisms and might represent a tool for estimating their clinical significance.

Respiratory challenge MRI: Practical aspects.

Respiratory challenge MRI is the modification of arterial oxygen (PaO2) and/or carbon dioxide (PaCO2) concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging. In this paper we review the rationale for respiratory challenge MRI including the effects of oxygen and carbon dioxide on the cerebral circulation. We also discuss the planning, equipment, monitoring and techniques that have been used to undertake these experiments. We finally propose some recommendations in this evolving area for conducting these experiments to enhance data quality and comparison between techniques.

Impact of Computed Tomography Perfusion Imaging on the Response to Tenecteplase in Ischemic Stroke: Analysis of 2 Randomized Controlled Trials.

Background: We pooled 2 clinical trials of tenecteplase compared with alteplase for the treatment of acute ischemic stroke, 1 that demonstrated superiority of tenecteplase and the other that showed no difference between the treatments in patient clinical outcomes. We tested the hypotheses that reperfusion therapy with tenecteplase would be superior to alteplase in improving functional outcomes in the group of patients with target mismatch as identified with advanced imaging. Methods: We investigated whether tenecteplase-treated patients had a different 24-hour reduction in the National Institutes of Health Stroke Scale and a favorable odds ratio of a modified Rankin scale score of 0 to 1 versus 2 to 6 compared with alteplase-treated patients using linear regression to generate odds ratios. Imaging outcomes included rates of vessel recanalization and infarct growth at 24 hours and occurrence of large parenchymal hematoma. Baseline computed tomography perfusion was analyzed to assess whether patients met the target mismatch criteria (absolute mismatch volume >15 mL, mismatch ratio >1.8, baseline ischemic core <70 mL, and volume of severely hypoperfused tissue <100 mL). Patients meeting target mismatch criteria were analyzed as a subgroup to identify whether they had different treatment responses from the pooled group. Results: Of 146 pooled patients, 71 received alteplase and 75 received tenecteplase. Tenecteplase-treated patients had greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 7; alteplase, 2; P=0.018) and less parenchymal hematoma (2 of 75 versus 10 of 71; P=0.02). The pooled group did not show improved patient outcomes when treated with tenecteplase (modified Rankin scale score 0–1: odds ratio, 1.77; 95% confidence interval, 0.89–3.51; P=0.102) compared with alteplase therapy. However, in patients with target mismatch (33 tenecteplase, 35 alteplase), treatment with tenecteplase was associated with greater early clinical improvement (median National Institutes of Health Stroke Scale score change: tenecteplase, 6; alteplase, 1; P<0.001) and better late independent recovery (modified Rankin scale score 0–1: odds ratio, 2.33; 95% confidence interval, 1.13–5.94; P=0.032) than those treated with alteplase. Conclusions: Tenecteplase may offer an improved efficacy and safety profile compared with alteplase, benefits possibly exaggerated in patients with baseline computed tomography perfusion–defined target mismatch. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926. URL: https://www.anzctr.org.au. Unique identifier: ACTRN12608000466347.

How many stroke patients might be eligible for mechanical thrombectomy

Introduction Recent studies showed improved patient outcomes with endovascular treatment of acute stroke compared to medical care, including IV rtPA, alone. Seven trials have reported results, each using different clinical and imaging criteria for patient selection. We compared eligibility for different trial protocols to estimate the number of patients eligible for treatment. Patients and methods Patient data were extracted from a single centre database that combined patients recruited to three clinical studies, each of which obtained both CTA and CTP within 6 h of stroke onset. The published inclusion and exclusion criteria of seven intervention trials (MR CLEAN, EXTEND–IA, ESCAPE, SWIFT-PRIME, REVASCAT, THERAPY and THRACE) were applied to determine the proportion that would be eligible for each of these studies. Results A total of 263 patients was included. Eligibility for IAT in individual trials ranged from 53% to 3% of patients; 17% were eligible for four trials and under 10% for two trials. Only three patients (1%) were eligible for all studies. The most common cause of exclusion was absence of large artery occlusion (LAO) on CTA. When applying simplified criteria requiring an ASPECT score > 6, 16% were eligible for IAT, but potentially 40% of these patients were excluded by perfusion criteria and more than half by common NIHSS thresholds. Conclusion Around 15% of patients presenting within 6 h of stroke onset were potentially eligible for IAT, but clinical trial eligibility criteria have much more limited overlap than is commonly assumed and only 1% of patients fulfilled criteria for all recent trials.

Tenecteplase in ischemic stroke offers improved recanalization: Analysis of 2 trials.

Objective: To test whether patients with complete vessel occlusion show greater recanalization at 24 hours and have improved clinical outcomes at 24 hours and 90 days when treated with tenecteplase compared to alteplase. Methods: Pooled clinical and imaging data from 2 phase 2 randomized trials comparing tenecteplase with alteplase allowed CT angiography (CTA) scans to be assessed centrally for occlusion status at baseline and at 24 hours post thrombolysis using the modified thrombolysis in cerebral infarction (TICI) scale. Twenty-four-hour poststroke NIH Stroke Scale (NIHSS) and 90-day modified Rankin Scale (mRS) scores were also compared between treatment groups using linear regression to generate odds ratios (ORs). Results: From 146 pooled patients, 69 had a TICI 0/1 occlusion overall at baseline. Tenecteplase-treated patients with a complete vessel occlusion had greater complete recanalization rates at 24 hours (71% for tenecteplase vs 43% for alteplase, p < 0.001). Patients with a TICI 0/1 occlusion who were treated with tenecteplase also showed greater early clinical improvement (median NIHSS change with tenecteplase was 9, interquartile range [IQR] 6, alteplase 1, IQR 1, p = 0.001) and higher rates of favorable 90-day outcomes (mRS 0–1 of tenecteplase compared with alteplase, OR 4.82, 95% confidence interval 1.02–7.84, p = 0.05). Conclusions: Tenecteplase may offer greater recanalization efficacy compared to alteplase, possibly exaggerated in patients with complete vessel occlusions on baseline CTA.

Coagulation and Fibrinolytic Activity of Tenecteplase and Alteplase in Acute Ischemic Stroke

Background and Purpose— We compared the fibrinolytic activity of tenecteplase and alteplase in patients with acute ischemic stroke, and explored the association between hypofibrinogenaemia and intracerebral hemorrhage. Methods— Venous blood samples from a subgroup of participants in the Alteplase–Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study were obtained at pretreatment, 3 to 12 hours, and 24±3 hours post-intravenous thrombolysis for analyses of plasminogen, plasminogen activator inhibitor-1, D-dimer, factor V, fibrinogen, and fibrin(ogen) degradation products, in addition to routine coagulation assays. Related sample Wilcoxon signed-rank tests were used to test the within-group changes, and independent Mann–Whitney tests for between-group differences. Results— Thirty patients were included (alteplase=14 and tenecteplase=16) with similar baseline demographics. Compared with baseline, alteplase caused significant hypofibrinogenaemia (P=0.002), prolonged prothrombin time (P=0.011), hypoplasminogenaemia (P=0.001), and lower factor V (P=0.002) at 3 to 12 hours after administration with persistent hypofibrinogenaemia at 24 hours (P=0.011), whereas only minor hypoplasminogenaemia (P=0.029) was seen in the tenecteplase group. Tenecteplase consumed less plasminogen (P<0.001) and fibrinogen (P=0.002) compared with alteplase. Conclusions— In patients with acute ischemic stroke, alteplase 0.9 mg/kg caused significant disruption of the fibrinolytic system, whereas tenecteplase 0.25 mg/kg did not, consistent with the trend toward lower intracerebral hemorrhage incidence with tenecteplase in the ATTEST study. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926.