Endovascular administration after intravenous infusion of thrombolytic agents for the treatment of patients with acute ischemic strokes

MR CLEAN, a multicenter randomized clinical trial of endovascular treatment for acute ischemic stroke in the Netherlands: study protocol for a randomized controlled trial

BACKGROUND

Endovascular or intra-arterial treatment (IAT) increases the likelihood of recanalization in patients with acute ischemic stroke caused by a proximal intracranial arterial occlusion. However, a beneficial effect of IAT on functional recovery in patients with acute ischemic stroke remains unproven. The aim of this study is to assess the effect of IAT on functional outcome in patients with acute ischemic stroke. Additionally, we aim to assess the safety of IAT, and the effect on recanalization of different mechanical treatment modalities.

METHODS/DESIGN

A multicenter randomized clinical trial with blinded outcome assessment. The active comparison is IAT versus no IAT. IAT may consist of intra-arterial thrombolysis with alteplase or urokinase, mechanical treatment or both. Mechanical treatment refers to retraction, aspiration, sonolysis, or use of a retrievable stent (stent-retriever). Patients with a relevant intracranial proximal arterial occlusion of the anterior circulation, who can be treated within 6 hours after stroke onset, are eligible. Treatment effect will be estimated with ordinal logistic regression (shift analysis); 500 patients will be included in the trial for a power of 80% to detect a shift leading to a decrease in dependency in 10% of treated patients. The primary outcome is the score on the modified Rankin scale at 90 days. Secondary outcomes are the National Institutes of Health stroke scale score at 24 hours, vessel patency at 24 hours, infarct size on day 5, and the occurrence of major bleeding during the first 5 days.

DISCUSSION

If IAT leads to a 10% absolute reduction in poor outcome after stroke, careful implementation of the intervention could save approximately 1% of all new stroke cases from death or disability annually.

TRIAL REGISTRATION

NTR1804 (7 May 2009)/ISRCTN10888758 (24 July 2012).

Impact of tissue plasminogen activator on the neurovascular unit: from clinical data to experimental evidence

About 15 million strokes occur each year worldwide. As the number one cause of morbidity and acquired disability, stroke is a major drain on public health-care funding, due to long hospital stays followed by ongoing support in the community or nursing-home care. Although during the last 10 years we have witnessed a remarkable progress in the understanding of the pathophysiology of ischemic stroke, reperfusion induced by recombinant tissue-type plasminogen activator (tPA-Actilyse) remains the only approved acute treatment by the health authorities. The objective of the present review is to provide an overview of our present knowledge about the impact of tPA on the neurovascular unit during acute ischemic stroke.

Current recommendations for endovascular interventions in the treatment of ischemic stroke

Ischemic stroke remains one of the leading cause of adult death and disability in the United States. Reperfusion of the occluded vessel is the standard of care in the setting of acute ischemic stroke according to established guidelines. Since the introduction of intravenous (IV) recombinant tissue plasminogen activator (rt-PA) in the late 1990s, significant advances have been made in methods to deliver thrombolytic agents and in devices for mechanical recanalization of occluded vessels. Furthermore, improvements in patient selection contribute to achievement of good clinical outcomes after endovascular therapy. This article summarizes findings from recent clinical trials and presents evidence-based guidelines for endovascular interventions in the treatment of ischemic stroke.

Therapeutic results of intra-arterial thrombolysis after full-dose intravenous tissue plasminogen activator administration

BACKGROUND AND PURPOSE

IV administration of tPA is accepted as a standard treatment for acute cerebral ischemia, but the clinical outcomes cannot be guaranteed in patients who are not recanalized after IV-tPA and in those who are not eligible for IV-tPA. In this study, outcomes from groups of patients treated with additional IA thrombolytic therapy with the use or omission of IV-tPA administration were compared.

MATERIALS AND METHODS

IA thrombolytic therapy (thrombolytic agents combined with mechanical intervention) was attempted in those patients who were not eligible for IV-tPA and who showed continuous major vessel occlusion after IV-tPA. Sixty-three patients were divided into 2 groups: a tPA group (n = 29, IA thrombolysis after IV-tPA) and a non-tPA group (n = 34, IA thrombolysis without IV-tPA). These groups were subdivided according to match or mismatch DWI/PWI after MR imaging. Treatment results were compared by recanalization rate, clinical outcome, mortality, and ICH rate.

RESULTS

The recanalization rate was 79.3% in the tPA group and 55.9% in the non-tPA group (χ(2) test, P < .05). Subgroup analysis between DWI/PWI mismatch in the tPA group and DWI/PWI mismatch in the non-tPA group also showed no statistical difference in recanalization rate, favorable clinical outcome, and mortality (χ(2) test, P > .05), but the significant ICH rate was high in the tPA group (χ(2) test, P < .05).

CONCLUSIONS

Additional IA thrombolytic treatment after full-dose IV-tPA administration might be an acceptable treatment option for patients with DWI/PWI mismatch.

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.

Methodology of the Interventional Management of Stroke III Trial

RATIONALE

The Interventional Management of Stroke (IMS) I and II pilot trials demonstrated that the combined intravenous (i.v.) and intraarterial (i.a.) approach to recanalization may be more effective than standard i.v. rt-PA (Activase) alone for moderate-to-large National Institutes of Health Stroke Scale (NIHSS>or=10) strokes, and with a similar safety profile.

AIMS

The primary objective of this NIH-funded, Phase III, randomized, multicenter, open-label clinical trial is to determine whether a combined i.v./i.a. approach to recanalization is superior to standard i.v. rt-PA alone when initiated within 3 h of acute ischemic stroke onset. The IMS III trial will develop and maintain a network of interventional centers to test the safety, feasibility, and potential efficacy of new FDA-approved catheter devices as part of a combined i.v./i.a. approach to recanalization as the IMS III study progresses. A secondary objective of the IMS III trial is to determine the cost-effectiveness of the combined i.v./i.a. approach as compared with standard i.v. rt-PA. Trial enrollment began in July of 2006.

DESIGN

A projected 900 subjects with moderate-to-large (NIHSS>or=10) ischemic strokes between ages 18 and 80 will be enrolled over the next 5 years at 40-plus centers in the United States and Canada. Patients must have i.v. treatment initiated within 3 h of stroke onset in both arms. Subjects will be randomized in a 2 : 1 ratio with more subjects enrolled in the combined i.v./i.a. group. The i.v. rt-PA alone group will receive the standard full dose [0.9 mg/kg, 90 mg maximum (10% as bolus)] of rt-PA intravenously over an hour. The combined i.v./i.a. group will receive a lower dose of i.v. rt-PA ( approximately 0.6 mg/kg, 60 mg maximum) over 40 min, followed by immediate angiography. If a treatable thrombus is not demonstrated, no i.a. therapy will be administered. If an appropriate thrombus is identified, treatment will continue with either the Concentric Merci thrombus-removal device, infusion of rt-PA and delivery of low-intensity ultrasound at the site of the occlusion via the EKOS Micro-Infusion Catheter, or infusion of rt-PA via a standard microcatheter. If i.a. rt-Pa therapy is the chosen strategy, a maximum of 22 mg of i.a. rt-PA may be given. The choice of i.a. strategy will be made by the treating neurointerventionalist. The i.a. treatment must begin within 5 h and be completed within 7 h of stroke onset.

STUDY OUTCOMES

The primary outcome measure is a favorable clinical outcome, defined as a modified Rankin Scale Score of 0-2 at 3 months. The primary safety measure is mortality at 3 months and symptomatic ICH within the 24 h of randomization.

Endovascular interventions following intravenous thrombolysis may improve survival and recovery in patients with acute ischemic stroke: a case-control study

BACKGROUND AND PURPOSE

Since the introduction of recombinant tissue plasminogen activator (rtPA) into clinical practice in the mid 1990s, no adjunctive treatment has further improved clinical outcomes in patients with ischemic stroke. The safety, feasibility, and efficacy of combining intravenous (IV) rtPA with endovascular interventions has been described; however, no direct comparative study has yet established whether endovascular interventions after IV rtPA are superior to IV rtPA alone. A retrospective case-control study was designed to address this issue.

MATERIALS AND METHODS

Between 2003 and 2006, 33 consecutive patients with acute ischemic stroke and National Institutes of Health Stroke Scale (NIHSS) scores >/=10 were treated with IV rtPA in combination with endovascular interventions (IV plus intervention) at a tertiary care facility. Outcomes were compared with a control cohort of 30 consecutive patients treated with IV rtPA (IV only) at a comparable facility where endovascular interventions were not available.

RESULTS

Baseline parameters were similar between the 2 groups. We found that the IV-plus-intervention group experienced significantly lower mortality at 90 days (12.1% versus 40.0%, P = .019) with a significantly greater improvement in NIHSS scores by the time of discharge or follow-up (P = .025). In the IV-plus-intervention group, patients with admission NIHSS scores between 10 and 15 and patients </=80 years of age showed the greatest improvement, with a significant change of the NIHSS scores from admission (P = .00015 and P = .013, respectively).

CONCLUSIONS

In this small case-control study of patients with acute ischemic stroke and admission NIHSS scores >/=10, there was a suggestion of incremental clinical benefit among patients receiving endovascular interventions following standard administration of IV rtPA.

Simultaneous treatment with intravenous recombinant tissue plasminogen activator and endovascular therapy for acute ischemic stroke within 3 hours of onset

BACKGROUND AND PURPOSE

Because intravenous (IV) recombinant tissue plasminogen activator (rtPA) does not always lead to a good outcome in a considerable proportion of patients, combined IV rtPA and rescue endovascular therapy (ET) have been performed in several recent studies. However, rescue therapy after completion of IV rtPA often results in late ineffective recanalization. We examined the efficacy and safety of combined IV rtPA and simultaneous ET as primary rather than rescue therapy for hyperacute middle cerebral artery (MCA) occlusion.

MATERIALS AND METHODS

A total of 29 patients eligible for IV rtPA, who were diagnosed as having MCA (M1 or M2) occlusion within 3 hours of onset, underwent thrombolysis. In the combined group, patients were treated by IV rtPA (0.6 mg/kg for 60 minutes) and simultaneous ET (intra-arterial rtPA, mechanical thrombus disruption with microguidewire, and balloon angioplasty) initiated as soon as possible. In the IV group, patients were treated by IV rtPA only.

RESULTS

The improvement of the National Institutes of Health Stroke Scale (NIHSS) score at 24 hours was 11 +/- 4.8 in the combined group versus 5 +/- 4.3 in the IV group (P < .001). In the combined group, successful recanalization was observed in 14 (88%) of 16 patients with no symptomatic intracranial hemorrhage, and 10 (63%) of 16 patients had favorable outcomes (modified Rankin Scale [mRS] 0, 1) at 3 months.

CONCLUSIONS

Aggressive combined therapy with IV rtPA and simultaneous ET markedly improved the clinical outcome of hyperacute MCA occlusion without significant adverse effect. Additional randomized study is needed to confirm our results.

Acute ischemic stroke: overview of recent therapeutic developments

Stroke, a disorder encompassing all cerebrovascular accidents, is a public health problem of immense proportions across the globe. Therapeutic efforts are directed at three aspects: prevention, acute treatment, and rehabilitation. Preventative measures, which in many instances mirror those for cardiovascular disease, can achieve the greatest public health impact. Measures that enhance the recovery of neurologic function and reduce neurologic disability after stroke can also affect a large population of handicapped stroke survivors. In the past 10 years, the greatest changes have occurred in the field of acute stroke treatment. Ultra-early-stage therapies with the potential to dramatically reverse severe neurologic deficits, or halt their progression, have caused a restructuring of the emergency care of neurologic patients. The parallels with the evolution of emergency treatment of acute coronary syndromes after 1970 are striking. This review focuses on aspects of stroke therapy that are either just entering, or soon to enter, current practice.

Future directions for recanalization therapy in acute ischemic stroke

Currently, the only treatment approved by the US Food and Drug Administration for the treatment of acute stroke is the intravenous recombinant tissue plasminogen activator, which must be administered within a 3 h window. The majority of ischemic stroke patients do not receive intravenous thrombolysis, primarily because they enter the healthcare system too late. Alternative treatment strategies being used or investigated include intra-arterial thrombolysis, endovascular clot disruption, and manipulation and angioplasty with or without stenting. The most promising new revascularization technologies beyond conventional thrombolysis for acute ischemic stroke are ultrasound-enhanced thrombolysis, mechanical clot extraction devices and stent angioplasty. Advances in neuroimaging may allow physicians to determine the etiology of a stroke and tailor treatment accordingly for the maximal clinical benefit for affected patients.

Brain tissue salvage in acute stroke

Thrombolysis is the only effective medical therapy of ultra-acute (<3 hours) cerebral ischemia, and it is moving from academic centers to community-based standard therapy in experienced centers. Despite intensive experimental and clinical research, the salvage of brain cells through a host of neuroprotective strategies has not been demonstrated to be efficient. As the imaging and other patient selection methods continue to develop, it may be possible eventually to identify patients who still have viable penumbral brain tissue even after the 3-h window. This review focuses on the possibilities of salvaging acutely ischemic brain tissue and potential reasons for differences in the efficacies of the thrombolytic and neuroprotective therapies.