Stroke Recombinant Tissue Plasminogen Activator Research Articles

PKM2 promotes neutrophil activation and cerebral thromboinflammation: therapeutic implications for ischemic stroke

There is a critical need for cerebro-protective interventions to improve the suboptimal outcomes of patients with ischemic stroke who have been treated with reperfusion strategies. We found that nuclear pyruvate kinase muscle 2 (PKM2), a modulator of systemic inflammation, was upregulated in neutrophils after the onset of ischemic stroke in both humans and mice. Therefore, we determined the role of PKM2 in stroke pathogenesis by using murine models with preexisting comorbidities. We generated novel myeloid cell–specific PKM2−/− mice on wild-type (PKM2fl/flLysMCre+) and hyperlipidemic background (PKM2fl/flLysMCre+Apoe−/−). Controls were littermate PKM2fl/flLysMCre– or PKM2fl/flLysMCre–Apoe−/− mice. Genetic deletion of PKM2 in myeloid cells limited inflammatory response in peripheral neutrophils and reduced neutrophil extracellular traps after cerebral ischemia and reperfusion, suggesting that PKM2 promotes neutrophil hyperactivation in the setting of stroke. In the filament and autologous clot and recombinant tissue plasminogen activator stroke models, irrespective of sex, deletion of PKM2 in myeloid cells in either wild-type or hyperlipidemic mice reduced infarcts and enhanced long-term sensorimotor recovery. Laser speckle imaging revealed improved regional cerebral blood flow in myeloid cell–specific PKM2-deficient mice that was concomitant with reduced post-ischemic cerebral thrombo-inflammation (intracerebral fibrinogen, platelet [CD41+] deposition, neutrophil infiltration, and inflammatory cytokines). Mechanistically, PKM2 regulates post-ischemic inflammation in peripheral neutrophils by promoting STAT3 phosphorylation. To enhance the translational significance, we inhibited PKM2 nuclear translocation using a small molecule and found significantly reduced neutrophil hyperactivation and improved short-term and long-term functional outcomes after stroke. Collectively, these findings identify PKM2 as a novel therapeutic target to improve brain salvage and recovery after reperfusion.

Magnitude of Benefit of Combined Endovascular Thrombectomy and Intravenous Fibrinolysis in Large Vessel Occlusion Ischemic Stroke.

Background and Purpose- Quantifying the benefit magnitude of combined endovascular thrombectomy (EVT) and intravenous thrombolysis (IVT) versus nonreperfusion care in patients with acute ischemic stroke caused by large vessel occlusion would aid organization of regional stroke care systems. Methods- NINDS rt-PA Study (National Institute for Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator) and SWIFT PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment) patients were matched for prognosis (based on age and National Institutes of Health Stroke Scale) and definite/likely anterior circulation large vessel occlusion (based on National Institutes of Health Stroke Scale total score and item pattern), using optimal inverse variance matching, to determine comparative outcomes with nonreperfusion care alone, IVT alone, and IVT+EVT. Results- Matching yielded 240 patients, including 80 each treated with nonreperfusion care, IVT alone, and IVT+EVT, with, respectively, mean age 67.1, 67.1, and 66.9 and presenting deficit severity (National Institutes of Health Stroke Scale) mean 15.8, 15.9, and 15.9. Outcomes at 3 months for IVT+EVT versus nonreperfusion care included freedom from disability (modified Rankin Scale score, 0-1) 48.1% versus 21.3%, P=0.0004; functional independence (modified Rankin Scale score, 0-2) 62.9% versus 32.6, P=0.0001; and reduced disability over all 7 modified Rankin Scale levels, common odds ratio 3.34, P<0.0001. Outcomes for IVT alone versus nonreperfusion care included: freedom from disability 30.0% versus 21.3%, P=0.28 and reduced disability over all 7 modified Rankin Scale levels, common odds ratio 1.14, P=0.65. Compared with nonreperfusion care, the number needed to treat with EVT+IVT for 1 more patient to have reduced disability was 1.8. Conclusions- Matched patient analysis across randomized trials provides evidence that the strategy of combined IVT and mechanical thrombectomy is a highly beneficial treatment strategy for acute ischemic stroke caused by large vessel occlusion patients. A reasonable effect magnitude estimate is that, among every 100 patients treated, combined IVT+EVT reperfusion therapy, compared with no reperfusion therapy, reduces long-term disability in 57, including conferring functional independence upon 30.

The Risk of Hemorrhagic Transformation After Thrombolysis for Acute Ischemic Stroke in Chinese Versus North Americans: A Comparative Study

There is a widespread belief that Asians are more susceptible to hemorrhagic transformation (HT) after receiving recombinant tissue-type plasminogen activator (rt-PA) for acute ischemic stroke (AIS). However, this has not been examined in clinical practice. This study aims to compare the incidence of symptomatic hemorrhagic transformation (SHT) among thrombolysis-treated AIS patients in China and in the United States. We compared 212 consecutive patients receiving thrombolysis within 4.5 hours of onset ± endovascular therapy from an American (n = 86) and a Chinese Stroke Center (n = 126). SHT was defined using various definitions based on the National Institute for Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator (NINDS rt-PA) trials, European-Australian Cooperative Acute Stroke Study 2 (ECASS2), and a modified version of Safe Implementation of Thrombolysis in Stroke-Monitoring Study (mSITS-MOST) study criteria. We used Firth logistic regression to adjust for confounding variables and to identify potential predictors. American patients were older, and had higher prevalence of diabetes, hypertension, cardiac disease, and prestroke use of antithrombotics. They also had higher baseline serum glucose, shorter onset-to-treatment time, and fewer endovascular treatments. The rates of SHT were higher in the American cohort compared to the Chinese cohort: 18.6% versus 14.3% based on NINDS definition of SHT; 15.1% versus 12.7% based on ECASS2; and 11.6% versus 7.2% based on mSITS-MOST. However, none of these differences were significant (unadjusted and adjusted P values > .05). Fatal HT was comparable in Americans versus Chinese (8.1% versus 8.7%). Serum glucose emerged as an independent predictor of SHT (P = .024). In our cohorts, the rate of SHT after thrombolysis is equivalent between Chinese and North American stroke patients.

Thirty Years After the National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Trial: A New Era for Stroke Therapy.

Thirty Years After the National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Trial: A New Era for Stroke Therapy.

Acute Ischemic Stroke with Very Early Clinical Improvement: A National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Stroke Trials Exploratory Analysis

A high proportion of patients excluded from recombinant tissue plasminogen activator (rt-PA) treatment because of rapid improvement occurring before treatment decision had incomplete recovery. The National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Trials dataset allows for systematic analyses of very early postrandomization improvement (VEPRIM) in stroke severity as a National Institutes of Health Stroke Scale (NIHSS) score was available for all subjects enrolled in the study at baseline (NIHSSB) and at 2 hours after randomization (NIHSS2H). We explored various definitions of VEPRIM to characterize predictive values for clinical outcomes. Post hoc analyses of the NINDS rt-PA Stroke Trials were conducted. VEPRIM was defined as the difference between the NIHSSB and the NIHSS2H scores using 3 approaches: raw, percent, and normalized change. We assessed the association between VEPRIM and 3-month favorable outcome (mRS score of 0-1), symptomatic intracerebral hemorrhage (sICH), and death. In the 624 subjects, every VEPRIM definition was independently associated with an increased probability of favorable outcome: for each unit of change within the VEPRIM definitions, there were 2%-24% (all P < .05) relative increased probability of favorable outcome, 2%-15% (all P < .05) decreased likelihood of death, and 2%-13% (all P < .05) decreased likelihood of sICH. Adjusting for NIHSSB and prestroke mRS scores, there was a significant rt-PA treatment effect for improvement seen for all 3 VEPRIM definitions. VEPRIM predicted favorable outcomes independent of definition and treatment arm. Patients with VEPRIM by any definition, while doing better than patients without VEPRIM, also derived increased clinical benefit when treated with rt-PA compared to placebo. Even with VEPRIM, a substantial percentage of patients had unfavorable outcomes.

Intravenous Thrombolysis for Acute Ischemic Stroke Occurring during Hospitalization for Transient Ischemic Attack

There are limited data regarding the use of intravenous thrombolysis in patients who experienced acute ischemic symptoms during their hospitalization for prior transient ischemic attack. We sought to prospectively evaluate the safety and efficacy of intravenous thrombolysis for the treatment of acute ischemic stroke occurring during hospitalization for transient ischemic attack in an international, multicenter study. Consecutive patients with acute ischemic stroke that occurred during hospitalization for prior transient ischemic attack were treated with intravenous thrombolysis in five tertiary-care stroke centers. Early arterial recanalization was determined by transcranial Doppler at the end of recombinant tissue plasminogen activator infusion using previously validated criteria. Symptomatic intracranial hemorrhage complicating intravenous thrombolysis was evaluated using the National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Stroke Study definition. Functional independence at three-months was defined as Modified Rankin Scale score of 0-2. Systemic recombinant tissue plasminogen activator infusion (median onset-to-treatment time 70 mins, interquartile range 50-150) was given in 25 consecutive patients (mean age 66 ± 10 years) who developed acute ischemic stroke symptoms (median National Institutes of Health Stroke Scale score 10 points; interquartile range 8-14) during hospitalization for prior transient ischemic attack (median ABCD(2) score 5 points; median time-to-symptom recurrence 24 h, interquartile range 24-48). No symptomatic intracranial hemorrhage (0%; 95% confidence interval 0-12%) was documented. Early complete recanalization occurred in 64% of patients (95% confidence interval 44-80%), and 84% (95% confidence interval 65-94%) achieved three-month functional independence. The rate of three-month functional independence was higher in patients treated with intravenous tissue plasminogen activator within 90 mins from symptom onset compared with those with onset-to-treatment time>90 mins (81% vs. 33%; P = 0.031). Intravenous thrombolysis for symptoms of acute ischemic stroke occurring after hospitalization for transient ischemic attack appears to be safe. These pilot data support resetting the clock if new symptoms recur shortly after transient ischemic attack.

Minimal sufficient balance-a new strategy to balance baseline covariates and preserve randomness of treatment allocation.

In many clinical trials, baseline covariates could affect the primary outcome. Commonly used strategies to balance baseline covariates include stratified constrained randomization and minimization. Stratification is limited to few categorical covariates. Minimization lacks the randomness of treatment allocation. Both apply only to categorical covariates. As a result, serious imbalances could occur in important baseline covariates not included in the randomization algorithm. Furthermore, randomness of treatment allocation could be significantly compromised because of the high proportion of deterministic assignments associated with stratified block randomization and minimization, potentially resulting in selection bias. Serious baseline covariate imbalances and selection biases often contribute to controversial interpretation of the trial results. The National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator Stroke Trial and the Captopril Prevention Project are two examples. In this article, we propose a new randomization strategy, termed the minimal sufficient balance randomization, which will dually prevent serious imbalances in all important baseline covariates, including both categorical and continuous types, and preserve the randomness of treatment allocation. Computer simulations are conducted using the data from the National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator Stroke Trial. Serious imbalances in four continuous and one categorical covariate are prevented with a small cost in treatment allocation randomness. A scenario of simultaneously balancing 11 baseline covariates is explored with similar promising results. The proposed minimal sufficient balance randomization algorithm can be easily implemented in computerized central randomization systems for large multicenter trials.

Enhancing Recovery After Acute Ischemic Stroke with Donepezil as an Adjuvant Therapy to Standard Medical Care: Results of a Phase IIa Clinical Trial

Our aim was to assess the safety, tolerability, and efficacy signal of early donepezil administration with regard to enhancing recovery in a diverse acute ischemic stroke population. This was a multicenter, single-arm, National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator trial-controlled, modified 2-stage adaptive clinical trial set in 2 tertiary care hospitals in the United States. Adults with ischemic stroke treated within 24 hours after onset of symptoms were included. The intervention studied was donepezil 5 mg/day for 30 days, followed by an increase to 10 mg/day for 60 days. Our main outcome measures included treatment-related adverse events and side effects. The primary favorable outcome was a 90-day National Institutes of Health Stroke Scale (NIHSS) score ≤1. Neurologic, cognitive, functional, and psychological outcomes were assessed longitudinally. Thirty-three adults (median age 66 years; 59% female; 39% received tissue plasminogen activator) initiated treatment with donepezil. There were no treatment-related serious adverse events. Three participants (9%) discontinued donepezil because of side effects and 3 participants (9%) required a reduction to 5 mg/day after titration to 10 mg/day. Fifteen participants (45%) had a favorable outcome (NIHSS score ≤1 at day 90), and the study met prespecified criteria for continuing to a randomized trial (P < .10). Statistically significant improvements from baseline were observed with several secondary cognitive measures, including the Trail Making Tests and Mini-Mental State Exam (P < .01 for both). Adjuvant donepezil therapy initiated within 24 hours of acute ischemic stroke was safe and tolerated at 5 mg/day to 10 mg/day. The study met a priori criteria to move forward with a randomized clinical trial.

Strokes With Minor Symptoms

Background and Purpose— The pivotal National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator trials excluded patients with ischemic stroke with specific minor presentations or rapidly improving symptoms. The recombinant tissue plasminogen activator product label notes that its use for minor neurological deficit or rapidly improving stroke symptoms has not been evaluated. As a result, patients with low National Institutes of Health Stroke Scale scores are not commonly treated in clinical practice. We sought to further characterize the patients with minor stroke who were included in the National Institute of Neurological Disorders and Stroke trials. Methods— Minor strokes were defined as National Institutes of Health Stroke Scale score ≤5 at baseline for this retrospective analysis, because this subgroup is most commonly excluded from treatment in clinical practice and trials. Clinical stroke syndromes were defined based on prespecified National Institutes of Health Stroke Scale item score clusters. Clinical outcomes were reviewed generally and within these cluster subgroups. Results— Only 58 cases had National Institutes of Health Stroke Scale scores of 0 to 5 in the National Institute of Neurological Disorders and Stroke trials (42 recombinant tissue plasminogen activator and 16 placebo), and 2971 patients were excluded from the trials due to “rapidly improving” or “minor symptoms” as the primary reason. No patients were enrolled with isolated motor symptoms, isolated facial droop, isolated ataxia, dysarthria, isolated sensory symptoms, or with only symptoms/signs not captured by the National Institutes of Health Stroke Scale score (ie, National Institutes of Health Stroke Scale=0). There were ≤3 patients with each of the other isolated deficits enrolled in the trial. Conclusions— The National Institute of Neurological Disorders and Stroke trials excluded a substantial number of strokes with minor presentations, those that were included were small in number, and conclusions about outcomes based on specific syndromes cannot be drawn. Further prospective, systematic study of this subgroup is needed.

A Matching Algorithm to Address Imbalances in Study Populations

Outcome from stroke is highly dependent on baseline conditions. Patients with stroke have a wide range of severities, ages, and etiologies and it has proven difficult to achieve randomization of key variables in clinical trials. We present a new post hoc approach to achieve balance among selected variables. To illustrate the approach, we rebalanced the National Institute of Neurological Diseases and Stroke Recombinant Tissue Plasminogen Activator trial, in which the contribution of baseline imbalances continues to be debated. We selected baseline stroke severity (National Institutes of Health Stroke Scale), age, and glucose as matching criteria. The closest matched placebo and treated subjects were identified based on nearness to each other in 3-dimensional Euclidean space. Matching was performed within the quintiles of National Institutes of Health Stroke Scale that have been previously used to assess balance. Subjects who could not be matched were eliminated. Outcomes were assessed using the original specified National Institute of Neurological Diseases and Stroke trial measures. We successfully matched the 2 arms resulting in nearly identical baseline characteristics and distribution among quintiles. Despite fewer subjects after outlier elimination, the primary outcome measures remained significantly improved. After rebalancing, the magnitude of benefit was reduced by 13% to 23%. Benefit was apparent mostly in the large vessel occlusion subtype. This study demonstrated the feasibility of rebalancing individual subjects within a randomized trial. After rebalancing and outlier elimination, recombinant tissue plasminogen activator continued to demonstrate improved outcome. That the apparent treatment effect was reduced suggests that imbalances contributed to the magnitude of the original National Institute of Neurological Diseases and Stroke outcomes. This method could in theory be applied to any data set to find matched subjects for outcome or other analyses.

Time of Day, Outcome, and Response to Thrombolytic Therapy: The National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Stroke Trial Experience

Circadian pattern for the onset of acute ischemic stroke has been described; however, data assessing an association between thrombolytic therapy efficacy and circadian rhythm are limited. We assessed the relationship between the time of stroke onset and neurologic outcomes after thrombolytic therapy for acute ischemic stroke in the National Institute of Neurological Disorders and Stroke (NINDS) Recombinant Tissue Plasminogen Activator (rt-PA) Stroke Trial. We conducted exploratory, post hoc analysis of 624 patients in the NINDS rt-PA Stroke Trial. Variables assessed included presenting time of day (4- and 6-hour time blocks), outcome variables, stroke subtypes, treatment assignment, and biological markers. Outcome variables included 3-month mortality, clinical outcome at 3 months, intracranial hemorrhage (ICH), computed tomography lesion volume at 3 months, and deterioration at 24 hours. The distribution of patients in the time blocks was balanced between the rt-PA and placebo groups. There was not a clear circadian variation in the stroke onset time. There were no associations detected between stroke onset time and clinical outcome, computed tomography lesion volume, and asymptomatic hemorrhage. Patients treated with rt-PA whose stroke onset was between 0401 and 0800 hours had less symptomatic ICH, whereas those who received rt-PA between 0000 and 0400 hours had a 43% incidence of symptomatic ICH. Patients in the placebo group who had stroke onset between 1801 and 2400 hours had lower chances for neurologic deterioration. Patients who had a stroke between 0001 and 0400 hours had the highest fibrinogen concentrations. We did not find a circadian pattern to time of day of stroke onset in the patients included in the NINDS rt-PA Stroke Trial. The effect of rt-PA treatment on favorable outcome was independent of time of day of stroke onset. Patients who received rt-PA between 4 and 8 am were less likely to develop symptomatic ICH.

To Phase 3 or Not to Phase 3?

See related article, pages 1803–1810. Decisions to progress new chemical entities, biologicals, or new treatment modalities into Phase 3 are usually based on small Phase 2 studies that are designed to assess safety and to explore efficacy.1–3 Based on these Phase 2 safety studies, both large and small companies have launched large Phase 3 programs that include 2 concurrently run studies, ie, Stroke-Acute Ischemic NXY Treatment (SAINT) I and SAINT II ASP I and Ancrod Stroke Program (ASP) II. When Phase 3 studies have failed to demonstrate efficacy for the whole population under study, subgroup analysis to identify patients who may have benefited from treatment has led to additional Phase 3, subsequently negative studies.4 In part as a result of this approach, the number of failed studies for treatment of acute ischemic stroke, especially for neuroprotection, has become legendary. In this issue, Mandava and Kent5 present a model to predict if the results of a single study are different from a pooled control population. The model calculates expected outcome using a pooled control population and the ±95% “prediction interval surfaces” using the baseline variables of the National Institutes of Health Stroke Scale and age. The outcome variables assessed in the model are mortality and the 90-day modified Rankin …

Percent Change on the National Institutes of Health Stroke Scale: A Useful Acute Stroke Outcome Measure

A single optimal outcome measure in acute stroke has not been established. Changes in neurologic deficits might be useful outcome measures in acute stroke because they can measure within-subject changes on the entire spectrum of the scales starting at baseline. We tested the ability of percent National Institutes of Health Stroke Scale (NIHSS) score change (baseline-3 months) to predict the traditional functional outcomes in acute stroke (modified Rankin Scale [mRS], Barthel Index, Glasgow Outcome Scale, final NIHSS score). We analyzed data sets from two acute stroke clinical trials involving 44 clinical research centers throughout the United States and 1899 randomized patients. The percent NIHSS score change predicted functional outcomes very well, all areas under the curve of 0.90 or greater with all P values less than .001 in receiver operating characteristic analysis. In the National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator (rt-PA) Acute Stroke Trial, benefit from rt-PA was confirmed by a greater improvement on the NIHSS score than with placebo (67% v 50%, P < .002). In moderate stroke severity (baseline NIHSS score 7-15) an improvement of at least 55% was the best predictor of functional independence at 3 months (mRS <or= 2). This novel approach to the NIHSS score as an outcome measure in acute stroke appears to be an additional useful analytic and communication tool.

Atherosclerotic Peripheral Vascular Disease Symposium II

Stroke is the third leading cause of death and a leading cause of adult disability in the United States.1 From a global perspective, stroke is also a leading cause of death and disability. The past 20 years have seen significant improvements in stroke prevention, yet each year, >700 000 people have a new or recurrent stroke.2,3 The medical and societal costs of stroke exceed $62 billion in the United States alone.4 Any intervention that could reverse or limit the effects of a stroke would have dramatic medical, societal, and public health benefits. This section will focus on treatment of acute ischemic stroke, which accounts for 80% to 85% of all strokes. Other recent publications have focused on therapies for intracerebral hemorrhage. Acute interventions to reduce the effects of an ischemic stroke can be organized into several main approaches: (1) reperfusion strategies (lytics, endovascular/mechanical); (2) neuroprotection; and (3) restoration, regeneration, and rehabilitation. ### Medical Therapies Thrombolytic therapies for acute ischemic stroke have been used or under study for 30 to 40 years, yet only recently has an agent been approved by the US Food and Drug Administration (FDA) and included in the treatment guidelines. Intravenous recombinant tissue plasminogen activator (rtPA) is the only FDA-approved medical therapy proven to reduce the effects of an ischemic stroke.5,6 Its main mechanism of action is to lyse a clot that is occluding a cerebral vessel, thereby reperfusing distal ischemic brain tissue and preventing or limiting the area of cell death and tissue necrosis. The efficacy of intravenous rtPA was proven in the pivotal National Institute of Neurological Disorders and Stroke (NINDS) rtPA study, which showed improved outcomes for patients treated within 3 hours of stroke onset.7 The NINDS tissue plasminogen activator (tPA) trial had an efficacy end point that was equivalent to the …

A Risk Score to Predict Intracranial Hemorrhage After Recombinant Tissue Plasminogen Activator for Acute Ischemic Stroke

Ability to predict risk of postthrombolysis intracerebral hemorrhage (ICH) is currently limited. Using data from the Multicenter Recombinant Tissue Plasminogen Activator Stroke Survey Group, we developed a score to predict this risk. One point was assigned for the presence of each of 4 variables: age older than 60 years, baseline National Institutes of Health Stroke Scale score greater than 10, glucose greater than 8.325 mmol/L, and platelet count less than 150,000/mm(3). Rate of any ICH increased with higher scores: 0 points, 2.6%; 1 point, 9.7%; 2 points, 15.1%; and greater than or equal to 3 points, 37.9%. The model had reasonable discriminatory capability (C-statistic 0.69). A similar pattern was seen with symptomatic and asymptomatic ICH separately, and with radiographically defined parenchymal hemorrhage. A simple risk score may be useful for predicting postthrombolysis ICH.

How important is surrogate consent for stroke research?

Patients with stroke may have cognitive deficits that impact their capacity to provide informed consent for research. Some institutional review boards restrict surrogate consent to persons who have specific legal authority to provide it. We examined the importance of surrogate consent in the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Trial, the study that led to the only US Food and Drug Administration-approved treatment for acute ischemic stroke. The NINDS rt-PA Stroke Trial randomized subjects with ischemic stroke to treatment with recombinant tissue plasminogen activator (rt-PA) or placebo. We compared the baseline characteristics and clinical outcomes of subjects enrolled by self-consent with those of subjects enrolled by surrogate consent. Surrogate consent was used to enroll 439 of 624 (70%) subjects. Subjects enrolled by surrogate consent were older (68.5 vs 63.4 years, p < 0.001), had more severe strokes (median NIH Stroke Scale score 17 vs 9, p < 0.001), and were less likely to make a good recovery (p < 0.001 for all measures) than patients who provided their own consent. There was no interaction between method of consent and response to rt-PA. If the trial had used the same sample size and recruited at the same rate but excluded patients who could not provide their own consent, it would have taken 12.5 years to complete. The National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator (rt-PA) Stroke Trial would not have been completed in a timely fashion without subjects enrolled by surrogate consent. Furthermore, exclusion of subjects who could not provide their own consent would have severely limited the generalizability and value of trial results.

Association of Serial Biochemical Markers With Acute Ischemic Stroke

Biochemical markers of acute neuronal injury may aid in the diagnosis and management of acute ischemic stroke. Serum samples from the National Institute for Neurological Disorders and Stroke (NINDS) recombinant tissue plasminogen activator Stroke Study were analyzed for the presence of 4 biochemical markers of neuronal, glial, and endothelial cell injury. These biochemical markers, myelin basic protein (MBP), neuron-specific enolase (NSE), S100beta, and soluble thrombomodulin, were studied for an association with initial stroke severity, infarct volume, and functional outcome. In the original NINDS study, serum samples were drawn from all patients on presentation to the Emergency Department and at approximately 2 and 24 hours after initiation of study therapy. In this analysis, stored serum samples were available for 359 patients; 107 patients had samples for all 3 time points. Serum marker concentrations were measured by ELISA techniques. We examined the relation between serum concentrations of each marker and the degree of baseline neurological deficit, functional outcome, and infarct size on computed tomography at 24 hours and the effect of fibrinolytic therapy. Higher 24-hour peak concentrations of MBP, NSE, and S100beta were associated with higher National Institutes of Health Stroke Scale baseline scores (r=0.186, P<0.0001; r=0.117, P=0.032; and r=0.263, P<0.0001, respectively). Higher peak concentrations of MBP and S100beta (r=0.209, P<0.0001; r=0.239, P<0.0001) were associated with larger computed tomography lesion volumes. Patients with favorable outcomes had smaller changes in MBP and S100beta (P<0.05) concentrations in the first 24 hours. Soluble thrombomodulin was not associated with any severity or outcome measure. This study corroborates previous work demonstrating correlations of MBP, NSE, and S100beta with clinical and radiographic features in acute stroke. Despite significantly better outcomes in the tissue plasminogen activator-treated group, we found no difference in the early release of the 4 biomarkers between treatment groups. Further study will define the role of biomarkers in acute stroke management and prognostication.

Acute stroke treatment; who is going to bleed?

The value of acute treatment for ischaemic stroke was initially demonstrated in 1995 by the National Institute of Neurological Disorders rt-PA Stroke Study Group (NINDS). 1 NINDSTissue plasminogen activator for acute ischemic stroke: the National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group. N Engl J Med. 1995; 333: 1581-1587 Crossref PubMed Scopus (9943) Google Scholar This indicated that patients treated by intravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) within 3 h of stroke onset are more likely to have minimal or no disability at 3 months. Sustained benefits at 1 year and cost-effectiveness have been shown in subsequent studies. 2 Kwiatkowski T.G. Libman R.B. Frankel M. et al. Effects of tissue plasminogen activator for acute ischemic stroke at 1 year: National Institute of Neurological Disorders Stroke Recombinant Tissue Plasminogen Activator Stroke Study Group. N Engl J Med. 1999; 340: 1781-1787 Crossref PubMed Scopus (503) Google Scholar , 3 Fagan S.C. Morgenstern L.B. Petitta A. et al. Cost-effectiveness of tissue plasminogen activator for acute ischemic stroke: NINDS rt-PA Stroke Study Group. Neurology. 1998; 50: 883-890 Crossref PubMed Scopus (338) Google Scholar The neuroimaging diagnostic technique used by most acute stroke treatment programmes is still computed tomography (CT). Indeed the 2005 update statement from the stroke council of the American Heart Association/American Stroke Association states that there are no data at present to show that magnetic resonance imaging (MRI) is superior to CT for selecting patients who could be treated with intravenous rt-PA. 4 Adams H. Adams R. Del Zoppo G. Goldstein L.B. Guidelines for the early management of patients with ischemic stroke. 2005 guidelines update. A scientific statement from the Stroke Council of the American Heart Association/American Stroke Association. Stroke. 2005; 36: 916-921 Crossref PubMed Scopus (381) Google Scholar

The Impact of Imbalances in Baseline Stroke Severity on Outcome in the National Institute of Neurological Disorders and Stroke Recombinant Tissue Plasminogen Activator Stroke Study

The National Institute of Neurological Disorders and Stroke (NINDS) Recombinant Tissue Plasminogen Activator (rtPA) Stroke Study demonstrated a clinically meaningful and statistically significant benefit of tissue plasminogen activator (tPA). Adjusting for the baseline National Institutes of Health (NIH) Stroke Scale, the benefit of tPA remained. However, other authors suggest that an imbalance in baseline stroke severity between the tPA and placebo groups confounded the results. Another issue that has been raised concerns a possible increase in early mortality for individuals given tPA. In post hoc subgroup analysis, we describe the effect of tPA across a spectrum of time from stroke onset to treatment and stroke severity subgroups. Stroke severity was based on the NIH Stroke Scale. We also compare early mortality (2-week and 30-day) in the tPA and placebo groups. Using combined data from the 2 NINDS rtPA Stroke Study trials, we performed post hoc subgroup analyses of 3-month favorable outcome (defined by the NIH Stroke Scale, Barthel, Rankin, and Glasgow Outcome Scales). We categorized patients from the trials into onset to treatment (0 to 90 minutes, 91 to 180 minutes) by NIH Stroke Scale (< or =5, 6 to 20, >20) subgroups. Analyses were adjusted for all variables previously shown to be associated with favorable outcome at 3 months. We also compared early mortality within onset-to-treatment subgroups. For all the 12 specified onset-to-treatment-NIH Stroke Scale subgroups, the adjusted odds ratio for a favorable 3-month outcome was greater than 1.0 and favored tPA. We detected no difference in mortality between patients treated with rtPA and those treated with placebo by 2 weeks posttreatment (rtPA=9%, placebo=13%; P =.49) or by 30 days (rtPA=11%, placebo=16%; P =.30). These are descriptive post hoc subgroup analyses. Using cut points defined in previous critiques of the NINDS trials, these analyses give results consistent with previous NINDS Study Group reports. Baseline NIH Stroke Scale imbalance does not account for the better outcome of rtPA-treated patients.

Admission glucose level and clinical outcomes in the NINDS rt-PA Stroke Trial.

Hyperglycemia during acute ischemic stroke may augment brain injury, predispose to intracerebral hemorrhage (ICH), or both. To analyze the relationship between admission glucose level and clinical outcomes from acute ischemic stroke, the authors performed multivariate regression analysis with the National Institute of Neurological Disorders and Stroke recombinant tissue plasminogen activator (rt-PA) Stroke Trial data. Neurologic improvement was defined as improvement on the NIH Stroke Scale by 4 or more points from baseline to 3 months, or a final score of zero. Favorable outcome was defined as both Glasgow Outcome score of 1 and Barthel Index 95 to 100 at 3 months. Symptomatic ICH was defined as CT-documented hemorrhage temporally related to clinical deterioration within 36 hours of treatment. Potential confounding factors were controlled, including acute treatment (rt-PA or placebo), age, baseline NIH Stroke Scale score, history of diabetes mellitus, stroke subtype, and admission blood pressure. There were 624 patients enrolled within 3 hours after stroke onset. As admission glucose increased, the odds for neurologic improvement decreased (odds ratio [OR] = 0.76 per 100 mg/dL increase in admission glucose, 95% CI 0.61 to 0.95, p = 0.01). The relation between admission glucose and favorable outcome depended on admission mean blood pressure (MBP): as admission MBP increased, the odds for favorable outcome related to increasing admission glucose levels progressively decreased (p = 0.02). As admission glucose increased, the odds for symptomatic ICH also increased (OR = 1.75 per 100 mg/dL increase in admission glucose, 95% CI 1.11 to 2.78, p = 0.02). Admission glucose level was not associated with altered effectiveness of rt-PA. In patients with acute ischemic stroke, higher admission glucose levels are associated with significantly lower odds for desirable clinical outcomes and significantly higher odds for symptomatic ICH, regardless of rt-PA treatment. Whether this represents a cause and effect relationship remains to be determined.