Methodology of the Interventional Management of Stroke III Trial

Fibrinolysis and Beyond: Bridging the Gap between Local and Systemic Clot Removal

Recanalization methods in ischemic stroke have been progressively expanded over the past years. In addition the continuous development of specialized mechanical devices for thrombectomy a broad spectrum of new drugs has been tested: Both options, novel drugs as well as new devices, can be employed independently of each other, but in most cases a combination of the two with the standard treatment of intravenous fibrinolysis is applied. Until recently, a large number of case series have been performed to investigate the effects of various drugs and interventions, but only a few trials have been conducted to determine the optimal conditions for combining both procedures. This review surveys the different systemic and endovascular vessel reopening practices and their major bridging techniques.

A trial on unruptured intracranial aneurysms (the TEAM trial): results, lessons from a failure and the necessity for clinical care trials

The trial on endovascular management of unruptured intracranial aneurysms (TEAM), a prospective randomized trial comparing coiling and conservative management, initiated in September 2006, was stopped in June 2009 because of poor recruitment (80 patients). Aspects of the trial design that may have contributed to this failure are reviewed in the hope of identifying better ways to successfully complete this special type of pragmatic trial which seeks to test two strategies that are in routine clinical use. Cultural, conceptual and bureaucratic hurdles and difficulties obstruct all trials. These obstacles are however particularly misplaced when the trial aims to identify what a good medical practice should be. A clean separation between research and practice, with diverging ethical and scientific requirements, has been enforced for decades, but it cannot work when care needs to be provided in the presence of pervasive uncertainty. Hence valid and robust scientific methods need to be legitimately re-integrated into clinical practice when reliable knowledge is in want. A special status should be reserved for what we would call 'clinical care trials', if we are to practice in a transparent and prospective fashion a medicine that leads to demonstrably better patient outcomes.

Comparison of acute nonthrombolytic and thrombolytic treatments in ischemic stroke patients 80 years or older

OBJECTIVES

The aim of this study was to compare the clinical outcomes of acute ischemic stroke patients 80 years or older treated with intravenous recombinant tissue plasminogen activator (i.v. rt-PA), or endovascular intervention with or without i.v. rt-PA, or nonthrombolytic medical treatment.

METHODS

This study was a retrospective, nonrandomized, observational study of patients, admitted within 9 hours of symptom onset, at 3 academic, university-affiliated hospitals. The main outcome measures were neurologic improvement, defined by improvement in National Institutes of Health Stroke Scale score at 7 days or discharge of 4 or more, or achieving a score of 0; symptomatic and asymptomatic intracerebral hemorrhage; favorable outcome (discharge modified Rankin score 0-2); and in-hospital mortality.

RESULTS

A total of 44 patients received i.v. rt-PA, 46 received endovascular intervention with or without i.v. rt-PA, and 66 received nonthrombolytic medical treatment. I.v. rt-PA-treated patients had a significantly clinically higher chance of favorable outcome (odds ratio [OR], 5.6; 95% confidence interval [CI], 1.8-17.5), when compared with nonthrombolytic medical treatment. A significantly higher rate of neurologic improvement was observed among the i.v. rt-PA (7.2; 95% CI, 2.7-19.5) and endovascularly treated patients (5.8; 95% CI, 2-16.8) when compared with nonthrombolytic medical treatment.

CONCLUSIONS

A prominently higher rate of neurologic improvement and favorable clinical outcome was observed among acute ischemic stroke patients 80 years or older treated with i.v. rt-PA or endovascular intervention when compared with nonthrombolytic medical treatment, supporting the use of acute thrombolytic therapies in this patient population when contraindications are not present.

Initial experience with a self-expanding retrievable stent for recanalization of large vessel occlusions in acute ischemic stroke

INTRODUCTION

Quicker recanalization results in better clinical outcomes in patients with acute ischemic strokes. We describe our experience with the use of a self-expanding, fully retrievable stent in acute intracranial occlusions.

METHODS

Patients who underwent intra-arterial procedures with a self-expanding, fully retrievable stent for acute ischemic strokes at our center in 2009 were included in this study. The primary outcome was recanalization [Thrombolysis in Myocardial Infarction (TIMI) grade 2/3] at end of procedure. Secondary endpoints were procedural interval times, incidence of vasospasm, rupture of vessels, device-related complications, groin complications, postprocedural intracerebral hemorrhage (ICH) on noncontrast CT, and all-cause mortality.

RESULTS

Fourteen patients (mean age 62.1 years, range 34-81 years; six males) were included in the study. Sites of occlusion are as follows: M1 middle cerebral artery (MCA, n = 8), M2 MCA (n = 1), proximal basilar artery (n = 1), and distal basilar artery (n = 4). An additional device or technique was used in 9 of 14 patients prior to the use of the retrievable stent. Twelve out of 14 (85.7%) achieved TIMI 2-3 recanalization with 4 of 14 (28.6%) achieving TIMI 3. Eight of 14 (57.1%) patients had modified Rankin Scale (0-2) at 3 months or discharge. ICH on follow-up CT was noted in 28.6% (4 of 14) of patients. All-cause mortality was 2 of 14 (14.3%).

CONCLUSION

Use of a novel self-expanding, fully retrievable stent resulted in fast and very high recanalization rates in acute ischemic strokes with intravascular occlusions.

Factors affecting the apparent efficacy and safety of tissue plasminogen activator in thrombotic occlusion models of stroke: systematic review and meta-analysis

Thrombolysis with recombinant tissue plasminogen activator (rtPA) improves outcome in animal models of stroke and in clinical trial, but is associated with increased intracranial hemorrhage. Here, we explore the impact of biologic and experimental design factors on efficacy and bleeding. We conducted a systematic review of studies describing the effect of tPA in thrombotic occlusion models of ischemic stroke followed by random effects meta-analysis, meta-regression, and trim and fill. We identified 202, 66, 128, and 54 comparisons reporting infarct volume, neurobehavioral score, hemorrhage, and mortality, respectively. The rtPA reduced infarct volume by 25.2% (95% confidence interval=21.8 to 28.6, 3388 animals), improved neurobehavioral score by 18.0% (12.6% to 23.3%, n=1243), increased the risk of hemorrhage (odds ratio=1.71, 1.42 to 2.07, n=2833) and had no significant effect on mortality (odds ratio=0.82, 0.62 to 1.08, n=1274). There was an absolute reduction in efficacy of 1.1% (0.7% to 1.4%) for every 10 minutes delay to treatment. Cumulative meta-analysis showed that the estimate of efficacy fell as more data became available. Publication bias inflated efficacy by 5.1% (infarct volume) and 8.1% (neurobehavioral score). This data set was large enough to be adequately powered to estimate with precision the impact of biologic and experimental factors on the efficacy and safety of rtPA.

Recanalization therapy for acute ischemic stroke, part 2: mechanical intra-arterial technologies

Stroke therapy has been revolutionized in the past two decades with the widespread implementation of chemical thrombolysis for acute stroke. However, chemical thrombolysis continues to be limited in its efficacy secondary to relatively short time windows and a high associated risk of hemorrhage. In an attempt to minimize hemorrhagic complications and extend the available therapeutic window, mechanical devices designed specifically for thrombus removal, clot obliteration, and arterial revascularization have experienced a recent surge in development and utilization. As such, chemical thrombolytics now represent only one of many options in acute stroke therapy. These new mechanical devices have extended the potential treatment window and now provide alternatives to patients who do not respond to conventional intravenous thrombolysis. This review will discuss the development of these devices, supporting literature, and the individual strengths that each engenders towards a life-saving therapy for stroke.

Low rates of acute recanalization with intravenous recombinant tissue plasminogen activator in ischemic stroke: real-world experience and a call for action

BACKGROUND AND PURPOSE

Acute rates of recanalization after intravenous (IV) recombinant tissue plasminogen activator (rt-PA) in proximal vessel occlusion have been estimated sparingly, typically using transcranial Doppler (TCD). We aimed to study acute recanalization rates of IV rt-PA in CT angiogram-proven proximal (internal carotid artery [ICA], M1 middle cerebral artery [MCA], M2-MCA, and basilar artery) occlusions and their effects on outcome.

MATERIALS AND METHODS

The CT angiogram database of the Calgary stroke program was reviewed for the period 2002 to 2009. All patients with proximal vessel occlusions receiving IV rt-PA who were assessed for recanalization by TCD or angiogram (for acute endovascular treatment) were included for analysis. Rates of acute recanalization as observed on TCD/first run of angiogram and postendovascular therapy recanalization rates were noted. Modified Rankin Scale score ≤2 at 3 months was used as a good outcome.

RESULTS

Among 1341 patients in the CT angiogram database, 388 patients with proximal occlusion were identified. Of these, 216 patients had received IV rt-PA; 127 patients underwent further imaging to assess recanalization. Among the patients undergoing TCD (n=46) and cerebral angiogram (n=103), only 27 (21.25%) patients had acute recanalization. By occlusion subtype, the rates of recanalization were: distal ICA (with or without ICA neck occlusion or stenotic disease) 1 of 24 (4.4%); M1-MCA (with or without ICA neck occlusion or stenotic disease) 21 of 65 (32.3%); M2-MCA 4 of 13 (30.8%); and basilar artery 1 of 25 (4%). Onset to rt-PA time was comparable in patients with and without recanalization. Recanalization (P<0.0001; risk ratio, 2.7; 95% confidence interval, 1.5-4.6) was the strongest predictor of outcome (adjusted for age and National Institutes of Health Stroke Scale score).

CONCLUSIONS

A low rate of acute recanalization was observed with IV rt-PA in proximal vessel occlusions identified by baseline CT angiogram. Recanalization was the strongest predictor of good outcome.

A Comparison of Computed Tomography Perfusion-Guided and Time-Guided Endovascular Treatments for Patients With Acute Ischemic Stroke

Background and Purpose— The role of CT perfusion (CT-P) imaging for the selection of patients with acute ischemic stroke who may benefit from endovascular treatment is not defined. The objective of this study was to determine whether CT-P-guided endovascular treatment improves clinical outcomes compared with standard endovascular treatment based on the time interval between symptom onset and presentation and noncontrast cranial CT imaging.

Methods— A retrospective study was performed comparing the clinical characteristics, complications, and clinical outcomes of patients with acute ischemic stroke who were treated using endovascular modalities based on either CT-P imaging (CT-P-guided) or time interval between symptom onset and presentation and absence of intracerebral hemorrhage or extensive ischemic changes on noncontrast cranial CT scan (time-guided).

Results— The rates of partial and complete recanalization were similar between the CT-P- and time-guided treatment groups (n=61 [88%] versus n=103 [81%]; P =0.52) regardless of whether they received intravenous recombinant tissue plasminogen activator before endovascular treatment. Comparing the CT-P-guided with the time-guided patients, favorable discharge outcome (modified Rankin Scale 0 to 2) was observed in 23 (32%) versus 41 (33%) of the patients, respectively ( P =0.9). In-hospital mortality was observed in 15 (21%) of CT-P- and 29 (23%) of time-guided patients ( P =0.74).

Conclusion— CT-P-guided endovascular treatment did not increase the rate of short-term favorable outcomes among patients with acute ischemic stroke. Prospective studies are required to validate the CT-P criteria and protocols currently in use before incorporating CT-P as a routine modality for patient selection for endovascular treatment.

Current practice versus willingness to enroll in clinical trials: paradox among vascular neurologists about treatment for acute ischemic stroke

BACKGROUND AND PURPOSE

Clinical trials are assessing the efficacy of fibrinolysis in extended time windows for acute ischemic stroke.

METHODS

An Internet-based survey was sent to 400 US vascular neurologists affiliated with a university to assess whether there are consensus opinions on how they treat patients beyond 3 hours from symptom onset and which patients they are willing to enroll into clinical trials of fibrinolysis for acute ischemic stroke.

RESULTS

We received 161 responses; 81% were male. Ninety-three percent of respondents treat patients with intravenous tissue plasminogen activator beyond 3 hours. More than 80% were treated beyond 3 hours with intra-arterial therapy (IAT). When asked if IAT improves stroke outcome, >50% selected the choice of "yes for middle cerebral artery and basilar occlusions" and only 2% selected the choice that "IAT does not improve outcome." Over half believe that imaging could be used to approximate the penumbra but with improvements to better identify salvageable tissue. Eighty-seven percent were willing to enroll patients into a placebo-controlled intravenous thrombolysis beyond 3 hours. For IAT trials, >80% would randomize beyond 3 hours with or without prior intravenous treatment.

CONCLUSIONS

Vascular neurologists have been treating acute ischemic stroke beyond 3 hours with intravenous tissue plasminogen activator even before the American Heart Association guidelines supported extending the therapeutic window. There is a paradox among the respondents willing to enroll patients into trials involving IAT given that a majority is offering IAT as part of their practice. These results suggest that clinical practice may impair enrollment into trials testing reperfusion therapies for acute ischemic stroke.

Thrombolytic therapy for acute ischemic stroke beyond three hours

BACKGROUND

Ischemic cerebrovascular accidents remain a leading cause of morbidity and mortality. Thrombolytic therapy for acute ischemic stroke within 3h of symptom onset of highly select patients has been advocated by some groups since 1995, but trials have yielded inconsistent outcomes. One recent trial demonstrated significant improvement when the therapeutic window was extended to 4.5h.

CLINICAL QUESTION

Does the intravenous systemic administration of tPA within 4.5h to select patients with acute ischemic stroke improve functional outcomes?

EVIDENCE REVIEW

All randomized controlled trials enrolling patients within 4.5h were identified, in addition to a meta-analysis of these trial data.

RESULTS

The National Institute of Neurological Disorders and Stroke (NINDS) and European Cooperative Acute Stroke Study III (ECASS III) clinical trials demonstrated significantly improved outcomes at 3 months, with increased rates of intracranial hemorrhage, whereas ECASS II and the Acute Noninterventional Therapy in Ischemic Stroke (ATLANTIS) study showed increased hemorrhagic complications without improving outcomes. Meta-analysis of trial data from all ECASS trials, NINDS, and ATLANTIS suggest that thrombolysis within 4.5h improves functional outcomes.

CONCLUSION

Ischemic stroke tPA treatment within 4.5h seems to improve functional outcomes and increases symptomatic intracranial hemorrhage rates without significantly increasing mortality.

Therapeutic hypothermia for acute ischemic stroke: ready to start large randomized trials?

Therapeutic hypothermia is a means of neuroprotection well established in the management of acute ischemic brain injuries such as anoxic encephalopathy after cardiac arrest and perinatal asphyxia. As such, it is the only neuroprotective strategy for which there is robust evidence for efficacy. Although there is overwhelming evidence from animal studies that cooling also improves outcome after focal cerebral ischemia, this has not been adequately tested in patients with acute ischemic stroke. There are still some uncertainties about crucial factors relating to the delivery of hypothermia, and the resolution of these would allow improvements in the design of phase III studies in these patients and improvements in the prospects for successful translation. In this study, we discuss critical issues relating first to the targets for therapy including the optimal depth and duration of cooling, second to practical issues including the methods of cooling and the management of shivering, and finally, of factors relating to the design of clinical trials. Consideration of these factors should inform the development of strategies to establish beyond doubt the place of hypothermia in the management of acute ischemic stroke.

Time to treatment with intravenous alteplase and outcome in stroke: an updated pooled analysis of ECASS, ATLANTIS, NINDS, and EPITHET trials

BACKGROUND

Early administration of intravenous recombinant tissue plasminogen activator (rt-PA) after ischaemic stroke improves outcome. Previous analysis of combined data from individual patients suggested potential benefit beyond 3 h from stroke onset. We re-examined the effect of time to treatment with intravenous rt-PA (alteplase) on therapeutic benefit and clinical risk by adding recent trial data to the analysis.

METHODS

We added data from ECASS III (821 patients) and EPITHET (100 patients) to a pool of common data elements from six other trials of alteplase for acute stroke (2775 patients). We used multivariate logistic regression to assess the relation of stroke onset to start of treatment (OTT) with treatment on favourable 3-month outcome (defined as modified Rankin score 0-1), mortality, and occurrence and outcome of clinically relevant parenchymal haemorrhage. The presence of an arterial occlusion was inferred from the patient's symptoms and absence of haemorrhage or other causes of ischaemic stroke. Vascular imaging was not a requirement in the trials. All patients with confirmed OTT within 360 min were included in the analysis.

FINDINGS

Treatment was started within 360 min of stroke onset in 3670 patients randomly allocated to alteplase (n=1850) or to placebo (n=1820). Odds of a favourable 3-month outcome increased as OTT decreased (p=0.0269) and no benefit of alteplase treatment was seen after around 270 min. Adjusted odds of a favourable 3-month outcome were 2.55 (95% CI 1.44-4.52) for 0-90 min, 1.64 (1.12-2.40) for 91-180 min, 1.34 (1.06-1.68) for 181-270 min, and 1.22 (0.92-1.61) for 271-360 min in favour of the alteplase group. Large parenchymal haemorrhage was seen in 96 (5.2%) of 1850 patients assigned to alteplase and 18 (1.0%) of 1820 controls, with no clear relation to OTT (p=0.4140). Adjusted odds of mortality increased with OTT (p=0.0444) and were 0.78 (0.41-1.48) for 0-90 min, 1.13 (0.70-1.82) for 91-180 min, 1.22 (0.87-1.71) for 181-270 min, and 1.49 (1.00-2.21) for 271-360 min.

INTERPRETATION

Patients with ischaemic stroke selected by clinical symptoms and CT benefit from intravenous alteplase when treated up to 4.5 h. To increase benefit to a maximum, every effort should be taken to shorten delay in initiation of treatment. Beyond 4.5 h, risk might outweigh benefit.

FUNDING

None.

Equipoise among recanalization strategies

Modern acute ischemic stroke therapy is based on the premise that recanalization and subsequent reperfusion are essential for the preservation of brain tissue and favorable clinical outcomes. We outline key issues that we think underlie equipoise regarding the comparative clinical efficacy of IV recombinant tissue-type plasminogen activator (rt-PA) and intra-arterial (IA) reperfusion therapies for acute ischemic stroke. On the one hand, IV rt-PA therapy has the benefit of speed with presumed lower rates of recanalization of large artery occlusions as compared to IA methods. More recent reports of major arterial occlusions treated with IV rt-PA, as measured by transcranial Doppler and magnetic resonance angiography, demonstrate higher rates of recanalization. Conversely, IA therapies report higher recanalization rates, but are hampered by procedural delays and risks, even failing to be applied at all in occasional patients where time to reperfusion remains a critical factor. Higher rates of recanalization in IA trials using clot-removal devices have not translated into improved patient functional outcome as compared to trials of IV therapy. Combined IV-IA therapy promises to offer advantages of both, but perhaps only when applied in the timeliest of fashions, compared to IV therapy alone. Where equipoise exists, randomizing subjects to either IV rt-PA therapy or IV therapy followed by IA intervention, while incorporating new interventions into the study design, is a rational and appropriate research approach.

Reperfusion for acute ischemic stroke: arterial revascularization and collateral therapeutics

PURPOSE OF REVIEW

Reperfusion of the ischemic territory forms the basis of most acute stroke treatments. This overview of the literature relating to reperfusion in acute ischemic stroke published within the last year provides a snapshot of a rapidly evolving aspect of cerebrovascular disease.

RECENT FINDINGS

Arterial revascularization from systemic thrombolysis to combination endovascular procedures to achieve recanalization has proliferated. Stroke imaging continues to discern features of critical pathophysiology that may influence tissue fate and clinical outcome. Balancing the risk of hemorrhagic transformation against the therapeutic aim to salvage the ischemic penumbra remains a formidable challenge. Collateral therapeutics that enhance perfusion outside the ischemic core present novel dimension to acute stroke therapy, focused on ischemia and not just the clot or plaque.

SUMMARY

These timely findings illustrate the essential role of reperfusion in acute stroke, delineating aspects of arterial revascularization and collateral therapeutics to be refined in coming years.

Current and future recanalization strategies for acute ischemic stroke

In a quest for stroke treatment, reperfusion proved to be the first key to the puzzle. Systemic tissue plasminogen activator (tPA), the first and currently the only approved treatment, is also the fastest way to initiate thrombolyis for acute ischemic stroke. tPA works by induction of mostly partial recanalization since stroke patients often have large thrombus burden. Thus, early augmentation of fibrinolysis and multi-modal approach to improve recanalization are desirable. This review focuses on the following strategies available to clinicians now or being tested in clinical trials: (a) faster initiation of tPA infusion; (b) sonothrombolysis; (c) intra-arterial revascularization, bridging intravenous and intra-arterial thrombolysis, mechanical thrombectomy and aspiration; and (d) novel experimental approaches. Despite these technological advances, no single strategy was yet proven to be a 'silver bullet' solution to reverse acute ischemic stroke. Better outcomes are expected with faster treatment leading to early, at times just partial flow improvement rather than achieving complete recanalization with lengthy procedures. Arterial re-occlusion can occur with any of these approaches, and it remains a challenge since it leads to poor outcomes and no clinical trial data are available yet to determine safe strategies to prevent or reverse re-occlusion.

Occurrence and predictors of futile recanalization following endovascular treatment among patients with acute ischemic stroke: a multicenter study

BACKGROUND AND PURPOSE

Although recanalization is the goal of thrombolysis, it is well recognized that it fails to improve outcome of acute stroke in a subset of patients. Our aim was to assess the rate of and factors associated with "futile recanalization," defined by absence of clinical benefit from recanalization, following endovascular treatment of acute ischemic stroke.

MATERIALS AND METHODS

Data from 6 studies of acute ischemic stroke treated with mechanical and/or pharmacologic endovascular treatment were analyzed. "Futile recanalization" was defined by the occurrence of unfavorable outcome (mRS score of > or = 3 at 1-3 months) despite complete angiographic recanalization (Qureshi grade 0 or TIMI grade 3).

RESULTS

Complete recanalization was observed in 96 of 270 patients treated with IA thrombolysis. Futile recanalization was observed in 47 (49%). In univariate analysis, patients with futile recanalization were older (73 +/- 11 versus 58 +/- 15 years, P < .0001) and had higher median initial NIHSS scores (19 versus 14, P < .0001), more frequent BA occlusion (17% versus 4%, P = .049), less frequent MCA occlusion (53% versus 76%, P = .032), and a nonsignificantly higher rate of symptomatic hemorrhagic complications (2% versus 9%, P = .2). In logistic regression analysis, futile recanalization was positively associated with age > 70 years (OR, 4.4; 95% CI, 1.9-10.5; P = .0008) and initial NIHSS score 10-19 (OR, 3.8; 95% CI, 1.7-8.4; P = .001), and initial NIHSS score > or = 20 (OR, 64.4; 95% CI, 28.8-144; P < .0001).

CONCLUSIONS

Futile recanalization is a relatively common occurrence following endovascular treatment, particularly among elderly patients and those with severe neurologic deficits.

Arterial Occlusion Sites on Magnetic Resonance Angiography Influence the Efficacy of Intravenous Low-Dose (0·6 mg/kg) Alteplase Therapy for Ischaemic Stroke

Aims

To determine the predictors of efficacy, including magnetic resonance imaging information, for low-dose intravenous alteplase therapy for stroke patients.

Methods

Seventy-eight patients were prospectively enrolled in a single Stroke Unit (SU) receiving alteplase at a dose of 0·6 mg/kg during the initial 27 months after its approval in Japan. Ischaemic changes and vascular lesions were identified using computed tomography, diffusion-weighted magnetic resonance imaging, and magnetic resonance angiography. Early ischaemic signs were assessed using the Alberta Stroke Program Early CT Score.

Results

The median baseline National Institutes of Health Stroke Scale score of 78 patients was 12. In 19 patients (24%), the National Institutes of Health Stroke Scale score improved by ≥8 points at 24 h. After multivariate adjustment, occlusion at the internal carotid artery (odds ratio 11·82, 95% confidence interval 1·73–142·74), Alberta Stroke Program Early CT Score on diffusion-weighted imaging ≤6 (15·23, 1·88–351·50), and a lower National Institutes of Health Stroke Scale score (1·24, 1·08–1·47, per 1-point decrease) were inversely correlated with early improvement. Four patients (5%) had symptomatic intracranial haemorrhage. At 3 months, 76 patients (98%) survived, and 36 of 78 patients (46%) overall, but only two of 19 patients (11%) with internal carotid artery occlusion, had a favourable functional outcome, corresponding to a modified Rankin scale score 1. After multivariate adjustment, internal carotid artery occlusion (odds ratio 15·84, 95% confidence interval 3·12–128·69) and Alberta Stroke Program Early CT Score on diffusion-weighted imaging ≤6(15·62, 1·78–410·12) were independent predictors of poor outcome.

Conclusions

Intravenous alteplase therapy at a dose of 0·6 mg/kg resulted in a relatively good overall outcome when compared with outcomes reported by western studies using an alteplase dose of 0·9 mg/kg. However, patients with occlusion at the internal carotid artery did not respond to this low-dose alteplase therapy.

Good clinical outcome after ischemic stroke with successful revascularization is time-dependent

BACKGROUND

Trials of IV recombinant tissue plasminogen activator (rt-PA) have demonstrated that longer times from ischemic stroke symptom onset to initiation of treatment are associated with progressively lower likelihoods of clinical benefit, and likely no benefit beyond 4.5 hours. How the timing of IV rt-PA initiation relates to timing of restoration of blood flow has been unclear. An understanding of the relationship between timing of angiographic reperfusion and clinical outcome is needed to establish time parameters for intraarterial (IA) therapies.

METHODS

The Interventional Management of Stroke pilot trials tested combined IV/IA therapy for moderate-to-severe ischemic strokes within 3 hours from symptom onset. To isolate the effect of time to angiographic reperfusion on clinical outcome, we analyzed only middle cerebral artery and distal internal carotid artery occlusions with successful reperfusion (Thrombolysis in Cerebral Infarction 2-3) during the interventional procedure (<7 hours). Time to angiographic reperfusion was defined as time from stroke onset to procedure termination. Good clinical outcome was defined as modified Rankin Score 0-2 at 3 months.

RESULTS

Among the 54 cases, only time to angiographic reperfusion and age independently predicted good clinical outcome after angiographic reperfusion. The probability of good clinical outcome decreased as time to angiographic reperfusion increased (unadjusted p = 0.02, adjusted p = 0.01) and approached that of cases without angiographic reperfusion within 7 hours.

CONCLUSIONS

We provide evidence that good clinical outcome following angiographically successful reperfusion is significantly time-dependent. At later times, angiographic reperfusion may be associated with a poor risk-benefit ratio in unselected patients.

The Alberta Stroke Program Early CT Score in Clinical Practice: What have We Learned?

The introduction of brain imaging with computed tomography revolutionised the treatment of patients with acute ischaemic stroke. With the visual differentiation of haemorrhagic stroke from ischaemic stroke, thrombolytic therapy became feasible. The Alberta Stroke Program Early CT Score was devised to quantify the extent of early ischaemic changes in the middle cerebral artery territory on noncontrast computed tomography. With its systematic approach, the score is simple and reliable. However, the assessment of early ischaemic changes and Alberta Stroke Program Early CT scoring require training. The Alberta Stroke Program Early CT Score is a strong predictor of functional outcome. Furthermore, the effectiveness of intraarterial thrombolysis in patients with middle cerebral artery occlusion shows effect modification by the Alberta Stroke Program Early CT Score. This review summarises the Alberta Stroke Program Early CT Score methodology. We illustrate current knowledge regarding Alberta Stroke Program Early CT Score applied to clinical trials and comment on how Alberta Stroke Program Early CT Score may facilitate clinical treatment decision making and future trial design. Moreover, we introduce a modification of the Alberta Stroke Program Early CT Score methodology that disregards isolated cortical swelling, i.e. focal brain swelling without associated parenchymal hypoattenuation, as early ischaemic changes in the Alberta Stroke Program Early CT Score system.

Safety and efficacy of alteplase in the treatment of acute ischemic stroke

After publication of the results of the National Institute of Neurological Disorders and Stroke study, the application of intravenous thrombolysis for ischemic stroke was launched and has now been in use for more than 10 years. The approval of this drug represented only the first step of the therapeutic approach to this pathology. Despite proven efficacy, concerns remain regarding the safety of recombinant tissue-type plasminogen activator for acute ischemic stroke used in routine clinical practice. As a result, a small proportion of patients are currently treated with thrombolytic drugs. Several factors explain this situation: a limited therapeutic window, insufficient public knowledge of the warning signs for stroke, the small number of centers able to administer thrombolysis on a 24-hour basis and an excessive fear of hemorrhagic complications. The aim of this review is to explore the clinical efficacy of treatment with alteplase and consider the hemorrhagic risks.

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.

Endovascular Therapy for Acute Ischemic Stroke

Background and Purpose— To review advances in endovascular therapy for acute ischemic stroke.

Methods— Data from primate studies, randomized studies of intravenous recombinant tissue-type plasminogen activator, and nonrandomized and randomized studies of endovascular therapy were reviewed.

Results— Clinical trial data demonstrate the superiority of endovascular treatment with thrombolytic medication or mechanical methods to reopen arteries compared with control patients from the PROACT II Trial treated with heparin alone. However, these same clinical trials, as well as preclinical primate models, indicate that recanalization, whether by endovascular approaches or standard-dose recombinant tissue-type plasminogen activator, is unlikely to improve clinical outcome after a certain time point. Although the threshold beyond which reperfusion has no or little benefit has yet to be conclusively defined, accumulated data to this point indicate an overall threshold of ≈6 to 7 hours. In addition, although the risk of symptomatic intracerebral hemorrhage is similar in trials of intravenous lytics and endovascular approaches, endovascular approaches have distinctive risk profiles that can impact outcome.

Conclusions— The treatment of acute ischemic stroke is evolving with new tools to reopen arteries and salvage the ischemic brain. Ongoing randomized trials of these new approaches are prerequisite next steps to demonstrate whether reperfusion translates into clinical effectiveness. Physiologic time to reperfusion will remain critical no matter which tools prove most effective and safest.

Intracranial thrombus extent predicts clinical outcome, final infarct size and hemorrhagic transformation in ischemic stroke: the clot burden score

BACKGROUND

In ischemic stroke, functional outcomes vary depending on site of intracranial occlusion. We tested the prognostic value of a semiquantitative computed tomography angiography-based clot burden score.

METHODS

Clot burden score allots major anterior circulation arteries 10 points for presence of contrast opacification on computed tomography angiography. Two points each are subtracted for thrombus preventing contrast opacification in the proximal M1, distal M1 or supraclinoid internal carotid artery and one point each for M2 branches, A1 and infraclinoid internal carotid artery. We retrospectively studied patients with disabling neurological deficits (National Institute of Health Stroke Scale score >or=5) and computed tomography angiography within 24-hours from symptom onset. We analyzed percentages independent functional outcome (modified Rankin Scale score <or=2), final infarct Alberta Stroke Program Early Computed Tomography Score and parenchymal hematoma rates across categorized clot burden score groups and performed multivariable analysis.

RESULTS

We identified 263 patients (median age 73-years, National Institute of Health Stroke Scale score 10, onset-to-computed tomography angiography time 165 min). Clot burden score<10 was associated with reduced odds of independent functional outcome (odds ratio 0.09 for clot burden score<or=5; odds ratio 0.22 for clot burden score 6-7; odds ratio 0.48 for clot burden score 8-9; all versus clot burden score 10; P<0.02 for all). Lower clot burden scores were associated with lower follow-up Alberta Stroke Program Early Computed Tomography Scores (P<0.02 for all). Lower clot burden scores were associated with lower follow-up Alberta Stroke Program Early CT Scores (P<0.001) and higher parenchymal hematoma rates (P=0.008). Inter-rater reliability for clot burden score was 0.87 (lower 95% confidence interval 0.71) and intra-rater reliability 0.96 (lower 95% confidence interval 0.92).

CONCLUSION

The quantification of intracranial thrombus extent with the clot burden score predicts functional outcome, final infarct size and parenchymal hematoma risk acutely. The score needs external validation and could be useful for patient stratification in stroke trials.