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Background and Purpose: Perfusion imaging is used for patient selection in clinical practice and trials. Postprocessing and definitions of tissue viability are nevertheless not standardized. We compared the lesion volumes generated with two well-recognized perfusion tissue definitions in a single-center phase 2 thrombolysis study.Methods: We analyzed perfusion imaging data from the Alteplase-Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study using two popular tissue viability thresholds (ischemic core definition: (1) cerebral blood volume < 2.0 mL/100 g-1 or (2) relative cerebral blood flow < 40% that of the contralesional hemisphere and relative delay time >2 seconds; penumbra definitions: (1) mean transit time > 145% of contralesional hemisphere or (2) relative delay time < 2 seconds). We compared volumes of core and penumbra, mismatch ratio, percentage, and volume of penumbra salvaged at 24 hours.Results: We included 73 (tenecteplase = 36, alteplase = 37) patients who had analyzable perfusion lesions at baseline. Significant differences were found in core volumes using the two thresholds (33 ± 37 mL vs. 26 ± 32 mL, P < .001), as was mismatch ratio (2.5 ± .9 vs. 4.2 ± 3.7, P < 0.001). The volume of penumbra salvaged at 24 hours (30 ± 19 mL vs. 35 ± 26 mL, P = .043) differed significantly, although the percentages of penumbra salvaged did not (P = .2). No difference was found between the two thrombolytic agents in the percentages of penumbra salvaged using either threshold.Conclusion: Two commonly used tissue definitions generated significantly different lesion volumes and mismatch ratios. Threshold selection may have significant impact on patient selection for trials or reperfusion therapies. [ABSTRACT FROM AUTHOR]

Background: Tenecteplase, a modified plasminogen activator with higher fibrin specificity and longer half-life, may have advantages over alteplase in acute ischemic stroke thrombolysis. Aims: We undertook an individual patient data meta-analysis of randomized controlled trials that compared alteplase with tenecteplase in acute stroke. Methods: Eligible studies were identified by a MEDLINE search, and individual patient data were acquired. We compared clinical outcomes including modified Rankin Scale at three months, early neurological improvement at 24 h, intracerebral hemorrhage, symptomatic intracerebral hemorrhage, and mortality at three months between all dose tiers of tenecteplase and alteplase. Results: Three relevant studies (Haley et al., Parsons et al., and ATTEST) included 291 patients and investigated three doses of tenecteplase (0.1, 0.25, 0.4 mg/kg). There were no differences between any dose of tenecteplase and alteplase for either efficacy or safety end points. Tenecteplase 0.25 mg/kg had the greatest odds to achieve early neurological improvement (OR [95%CI] 3.3 [1.5, 7.2], p = 0.093), excellent functional outcome (modified Rankin Scale 0-1) at three months (OR [95%CI] 1.9 [0.8, 4.4], p = 0.28), with reduced odds of intracerebral hemorrhage (OR [95%CI] 0.6 [0.2, 1.8], P = 0.43) compared with alteplase. Only 19 patients were treated with tenecteplase 0.4 mg/kg, which showed increased odds of symptomatic intracerebral hemorrhage compared with alteplase (OR [95% CI] 6.2 [0.7, 56.3]). Conclusions: While no significant differences between tenecteplase and alteplase were found, point estimates suggest potentially greater efficacy of 0.25 and 0.1 mg/kg doses with no difference in symptomatic intracerebral hemorrhage, and potentially higher symptomatic intracerebral hemorrhage risk with the 0.4 mg/kg dose. Further investigation of 0.25 mg/kg tenecteplase is warranted. [ABSTRACT FROM AUTHOR]

Summary 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. [ABSTRACT FROM AUTHOR]