Randomized Trial of Intraarterial Infusion of Urokinase Within 6 Hours of Middle Cerebral Artery Stroke

Identifying patients at high risk for poor outcome after intra-arterial therapy for acute ischemic stroke

BACKGROUND AND PURPOSE

Intra-arterial recanalization therapy (IAT) is increasingly used for acute stroke. Despite high rates of recanalization, the outcome is variable. We attempted to identify predictors of outcome that will enable better patient selection for IAT.

METHODS

All patients who underwent IAT at the University of Texas Houston Stroke Center were reviewed. Poor outcome was defined as modified Rankin Scale score 4 to 6 on hospital discharge. Findings were validated in an independent data set of 175 patients from the University of California at Los Angeles Stroke Center.

RESULTS

One hundred ninety patients were identified. Mean age was 62 years and median baseline National Institutes of Health Stroke Scale score was 0.18. Recanalization rate was 75%, symptomatic hemorrhage rate was 6%, and poor outcome rate was 66%. Variables associated with poor outcome were: age, baseline National Institutes of Health Stroke Scale, admission glucose, diabetes, heart disease, previous stroke, and the absence of mismatch on the pretreatment MRI. Logistic regression identified 3 variables independently associated with poor outcome: age (P=0.049; OR, 1.028), National Institutes of Health Stroke Scale (P=0.013; OR, 1.084), and admission glucose (P=0.031; OR, 1.011). Using these data, we devised the Houston IAT score: 1 point for age >75 years; 1 for National Institutes of Health Stroke Scale score >18, and 1 point for glucose >150 mg/dL (range, 0 to 3 mg/dL). The percentage of poor outcome by Houston IAT score was: score of 0, 44%; 1, 67%; 2, 97%; and 3, 100%. Recanalization rates were similar across the scores (P=0.4). Applying Houston IAT to the external cohort showed comparable trends in outcome and nearly identical rates in the Houston IAT therapy 3 tier.

CONCLUSIONS

The Houston IAT score estimates the chances of poor outcome after IAT, even with recanalization. It may be useful in comparing cohorts of patients and when assessing the results of clinical trials.

Endovascular approaches to acute stroke, part 2: a comprehensive review of studies and trials

Reperfusion remains the mainstay of acute ischemic stroke treatment. Endovascular therapy has become a promising alternative for patients who are ineligible for or have failed intravenous (IV) thrombolysis. The conviction that recanalization of properly selected patients is essential for the achievement of good clinical outcomes has led to the rapid and widespread growth in the adoption of endovascular stroke therapies. However, comparisons of the recent reperfusion studies have brought into question the strength of the association between revascularization and improved clinical outcome. Despite higher rates of recanalization, the mechanical thrombectomy studies have demonstrated substantially lower rates of good outcomes compared with IV and/or intra-arterial thrombolytic trials. However, such analyses disregard important differences in clot location and burden, baseline stroke severity, time from stroke onset to treatment, and patient selection in these studies. Many clinical trials are testing novel devices and drugs as well as the paradigm of physiology-based stroke imaging as a treatment-selection tool. The objective of this article is to provide a comprehensive review of the relevant past, current, and upcoming data on endovascular stroke therapy with a special focus on the prospective studies and randomized clinical trials.

Treatment effects for which shift or binary analyses are advantageous in acute stroke trials

BACKGROUND

In acute stroke trials, functional outcome may be analyzed by dichotomizing ordinal outcome scales or by evaluating the entire scale range (shift analysis). The conditions under which shift or binary analysis will be more efficient have not been previously well delineated.

METHODS

Model randomized clinical trials employing the modified Rankin Scale of global handicap were constructed to reflect 1) mild benefits experienced across all ranges of stroke severity (neuroprotective effect), 2) substantial benefits across all ranges of stroke severity (early recanalization effect), 3) substantial benefits across wide range of stroke severity but with limited ability to achieve fully normal outcome (late recanalization effect), 4) benefits clustered at unexpected health state transitions.

RESULTS

In neuroprotective models, shift analysis was the most efficient technique in detecting a treatment effect. In the early recanalization models, dichotomization at excellent outcome and shift analysis were of comparable efficiency, both superior to dichotomization at good outcome. In the late recanalization models, dichotomization at good outcome performed best, shift analysis less well, and dichotomization at excellent outcome poorly. In the unexpected benefits model, shift analysis substantially outperformed dichotomization analyses. These patterns held among the seven actual acute trials reporting full range Rankin outcomes and showing treatment benefit identified in the literature.

CONCLUSIONS

The pattern of treatment effect of the intervention determines whether shift analysis or simple dichotomized analysis will be more efficient. Shift analysis is especially advantageous when treatments confer a relatively uniform, mild benefit to patients over a wide range of stroke severities or confer benefits at unexpected but clinically important health state transitions.

A method to determine stroke trial success using multidimensional pooled control functions

BACKGROUND AND PURPOSE

Many early phase trials in stroke have not been subsequently confirmed. Randomization balance in baseline factors that influence outcome are difficult to achieve and may be partly responsible for misleading early results. We hypothesized that comparison with an outcome function derived from a large number of pooled control arms would mitigate these randomization problems and provide a reliable predictor for decision-making before proceeding to later phase trials. We developed such a model and added a novel feature of generation of multidimensional 95% prediction surfaces by which individual studies could be compared. We performed a proof-of-principle study with published clinical trials, determining whether our method correctly identified known outcomes.

METHODS

The control arms from all randomized, controlled trials for acute stroke with >or=10 subjects, including baseline National Institute of Health Stroke Scale, age, and 3-month outcomes published between 1994 and May 2008, were identified. A Matlab program (PPREDICTS) was written to generate outcome functions based on these parameters. Published treatment trials were compared with these 95% intervals to determine whether it successfully identified positive and negative trials.

RESULTS

Models of mortality and functional outcome were successfully generated (mortality: R(2)=0.69; functional outcome, modified Rankin Scale 0 to 2: R(2)=0.81; both P<0.0001). The National Institute of Neurological Diseases and Stroke intravenous recombinant tissue plasminogen activator trial and 3 studies yet to be subjected to Phase III study had modified Rankin Scale 0 to 2 outcomes above the 95% prediction interval. Sixteen treatment arm outcomes fell within prediction surface bounds. This group included 2 major trials, Stroke-Acute Ischemic NXY Treatment and Abciximab Emergent Stroke Treatment Trial, that initially appeared promising but went on to negative Phase III results.

CONCLUSIONS

This proof-of-principle analysis confirmed all positive and negative clinical stroke trial results and identified some promising therapies. The use of a pooled standard treatment group function combined with statistical bounds may improve selection of early studies for further study. This method may be applicable to any condition in which baseline factors influence outcome and at any stage of the development process.

Ischemic middle cerebral artery stroke missing the tissue plasminogen activator time window: transcranial Doppler evaluation

We investigated the interconnection between natural history of middle cerebral artery (MCA) recanalization by transcranial Doppler (TCD) and stroke severity in patients not treated by fibrinolysis. A total of 54 patients with an acute MCA stroke were examined within the first 24 hours and again within 120 hours after stroke onset. The first TCD examination detected 16 patients (29.6%) with complete occlusion, 27 patients (50%) with partial occlusion, and 11 patients (20.4%) with patent MCA. There were no significant differences among groups according to mean National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scale values. The second examination revealed 7 patients (13.2%) with complete occlusion, 31 patients (58.5%) with partial occlusion, and 15 patients (28.3%) with patent MCA. The mean NIHSS score in patients with total occlusion was significantly higher than in patients without occlusion or with partial occlusion. There was no significant difference in mean NIHSS value between patients with and without improvement on the second TCD examination. We conclude that MCA occlusion by TCD is associated with more severe stroke than that of patients without occlusion or with only a partial occlusion. A later MCA recanalization is not accompanied by significant improvement of neurologic or functional status.

Novel thrombolytic drugs: will they make a difference in the treatment of ischaemic stroke?

Treatment of acute ischaemic stroke aims to recanalize the occluded artery, salvage the at-risk brain tissue and thus minimize neurological sequelae. Efforts a decade ago have led to the only currently approved medical treatment for acute ischaemic stroke, i.e. intravenous alteplase given within 3 hours of stroke onset. Recanalization occurs in only one-half of the patients receiving alteplase, and only approximately 5% of all ischaemic stroke patients in industrialized countries receive this treatment. Studies are currently being carried out to determine whether intravenous alteplase would be safe and effective for up to 4.5 hours after ischaemic stroke onset, and whether it should be followed by an intra-arterial approach. Two novel thrombolytic drugs being studied for acute ischaemic stroke are desmoteplase and tenecteplase. Although the first trials were promising, the most recent evidence suggests that desmoteplase is not superior to placebo, even in carefully selected patients, in the 3- to 9-hour time window after stroke onset. Tenecteplase has only been studied for acute ischaemic stroke in a single noncontrolled, dose-finding trial in the 3-hour time window after stroke onset, which suggested a similar efficacy to that demonstrated in the historical data from the alteplase trials. A trial to compare the safety and efficacy of tenecteplase versus alteplase is ongoing. Safer and more effective thrombolytic drugs for the treatment of ischaemic stroke are thus being sought. Such agents will be welcome, but they are not here yet. While waiting we are likely to see the emergence of additive therapies, including ultrasound insonation, neuroprotective/regenerative agents and invasive intra-arterial techniques. Novel thrombolytic drugs, or other novel therapies, possess great potential to make a difference in the future, but the most urgent priority now is in the organization of stroke treatment in such a way that more patients receive the currently available optimal treatments.

The development of stroke therapeutics: promising mechanisms and translational challenges

Ischemic stroke is the second most common cause of death worldwide and a major cause of disability. Intravenous thrombolysis with rt-PA remains the only available acute therapy in patients who present within 3h of stroke onset other than the recently approved mechanical MERCI device, substantiating the high unmet need in available stroke therapeutics. The development of successful therapeutic strategies remains challenging, as evidenced by the continued failures of new therapies in clinical trials. However, significant lessons have been learned and this knowledge is currently being incorporated into improved pre-clinical and clinical design. Furthermore, advancements in imaging technologies and continued progress in understanding biological pathways have established a prolonged presence of salvageable penumbral brain tissue and have begun to elucidate the natural repair response initiated by ischemic insult. We review important past and current approaches to drug development with an emphasis on implementing principles of translational research to achieve a rigorous conversion of knowledge from bench to bedside. We highlight current strategies to protect and repair brain tissue with the promise to provide longer therapeutic windows, preservation of multiple tissue compartments and improved clinical success.

Randomized clinical stroke trials in 2007

This article reviews the randomized control trials (RCT’s) that were published in 2007 of emerging pharmacotherapies in patients with acute (≤ 2 weeks), sub-acute (2 to 12 weeks) and chronic (≥ 12 weeks) stroke. A Medline search generated 22 RCT’s in stroke in the year 2007 in the English language. These trials were primarily efficacy studies. These included the role of statins (an anti-lipid agent) in reducing post-stroke morbidity and mortality, and decreasing the carotid atherosclerotic plaque in middle aged patients at increased risk of cardiovascular disease; glucose-potassium-insulin infusion in hyperglyceamic acute stroke patients; pioglitazone (an anti-diabetic medication) to reduce recurrence of stroke in Type 2 diabetic patients; administration of intra-arterial urokinase (a thrombolytic agent) and the role of laser therapy in clot dissolution given that at present there is only one FDA approved thrombolytic agent (r TPA); benefit of warfarin (an anticoagulant) in elderly patients with atrial fibrillation in the community; NXY (a free radical trapping agent) and minocycline both tested as neuroprotectants; and zoledronate (an intravenous bisphosphonate) to prevent loss of bone mineral density of the affected extremity, and finally the role of nicardipine (a Calcium channel blocker) in the prevention of vasospasm, and hydrocortisone to prevent hyponatraemia after sub-arachnoid hemorrhage. Finally the role of non-pharmacotherapy like stents for patient’s with internal carotid artery dissection with tandem internal carotid and middle cerebral artery occlusion and in vertebral artery stenosis.

Vertebrobasilar recanalization after 12 h of onset using balloon expandable stent and thrombolysis

Basilar artery (BA) thrombosis is a severe condition that has a high percentage of mortality if no treatment is performed. Recanalization is the most successful way of reducing mortality and improving outcome in patients with BA thrombosis. We present a case of a patient that presented to our hospital 12 h after onset of symptoms in which a combination of techniques were used to perform a vertebrobasilar recanalization.

The Penumbra System: a mechanical device for the treatment of acute stroke due to thromboembolism

BACKGROUND AND PURPOSE

Data from recent reports have indicated that mechanical thrombectomy may have potential as a treatment for acute ischemic stroke. The purpose of this study was to assess the safety and performance of the Penumbra System (PS): a novel mechanical device designed to reduce clot burden in acute stroke due to large-vessel occlusive disease.

MATERIALS AND METHODS

A prospective, single arm, independently monitored and core laboratory adjudicated trial enrolled subjects with an acute neurologic deficit consistent with acute stroke, presenting within 8 hours of symptom onset and an angiographically verified occlusion (Thrombolysis in Myocardial Infarction [TIMI] grade 0 or 1) of a treatable intracranial vessel. The primary end point was revascularization of the target vessel to TIMI grade 2 or 3. Secondary end points were the proportion of subjects who achieved a modified Rankin Scale (mRS) score of 2 or less or a 4-point improvement on the National Institutes of Health Stroke Scale (NIHSS) score at 30-day follow-up, as well as all-cause mortality.

RESULTS

Twenty-three subjects were enrolled, and 21 target vessels were treated in 20 subjects by the PS. At baseline, mean age was 60 years, mean mRS score was 4.6, and mean NIHSS score was 21. Postprocedure, all 21 of the treated vessels (100%) were successfully revascularized by the PS to TIMI 2 or 3. At 30-day follow-up, 9 subjects (45%) had a 4-point or more NIHSS improvement or an mRS of 2 or less. The all-cause mortality rate was 45% (9 of 20), which is lower than expected in this severe stroke cohort, where 70% of the subjects at baseline had either an NIHSS score of more than 20 or a basilar occlusion.

CONCLUSION

Thus, early clinical experience suggests that the PS allows revascularization in certain subjects experiencing acute ischemic stroke.

Guidelines for management of ischaemic stroke and transient ischaemic attack 2008

This article represents the update of the European Stroke Initiative Recommendations for Stroke Management. These guidelines cover both ischaemic stroke and transient ischaemic attacks, which are now considered to be a single entity. The article covers referral and emergency management, Stroke Unit service, diagnostics, primary and secondary prevention, general stroke treatment, specific treatment including acute management, management of complications, and rehabilitation.

Potential risk and protective factors for in-hospital mortality in hyperacute ischemic stroke patients

In the era of thrombolytic therapy for hyperacute ischemic stroke, most investigators have focused their attention on the factors influencing mortality and functional outcomes in patients treated with thrombolysis, but very few have focused on these factors among patients not receiving thrombolysis. The aim of this study was to investigate the prognostic factors for mortality in all hyperacute stroke patients with or without thrombolysis. In 2005, we enrolled 101 ischemic stroke patients (43 females, 58 males; mean age, 68 years) who were transported to the emergency department (ED) within 4 hours of symptom onset. The overall in-hospital mortality rate was 17.8% (18/101). According to t test analysis, age (p = 0.034), time interval from neurologist consultation (p < 0.0001) and ED to ward admission (p = 0.001), Glasgow coma scale (GCS) (p = 0.001), National Institutes of Health Stroke Scale (NIHSS) (p < 0.0001) and the sum of major risk factors of cerebrovascular disease (CVD) (p < 0.0001) were significantly different between mortality and survivor groups. Further Chi-squared test analysis revealed significant differences in the presenting consciousness disturbance (p = 0.001), place of attack (p = 0.04), and referral transportation (p = 0.008) between these groups. In conclusion, old age, delay between neurologist consultation and ward admission, severity of stroke, and multiple risk factors of CVD are significant risk factors for in-hospital mortality. Conversely, being free of initial consciousness disturbance, living in an urban area, and having direct transportation to a stroke center are protective factors in survivors. The concept of "brain attack" should be re-emphasized among ED physicians. The interconnection between stroke centers and emergency medical systems (EMS) should be more tightly built to promote timely management for hyperacute stroke care.

Prognostic value of transcranial sonography in acute stroke patients

Accurate assessment of stroke is critical for patient prognosis and selection of appropriate treatment regimens in order to optimize patient outcomes. Advanced neurosonologic techniques are straightforward, portable, and cost-effective, representing significant advantages over other noninvasive imaging modalities for monitoring of the hemodynamic status of acute ischemic stroke. Ultrasound findings acquired both early (<3 h from onset of stroke) and later (6-24 h after stroke) have demonstrated feasibility and validity for the detection of stenosis/occlusion of key intracranial structures, such as the middle cerebral artery, and for immediate and unambiguous indication of flow velocities, particularly when contrast enhancement is used. In addition, the target of thrombolysis can be identified and localized, and the success of therapy monitored, by transcranial ultrasound. Finally, transcranial ultrasound can be used to gauge the appropriateness of more complex and costly imaging studies, thereby optimizing utilization of health care resources.