Endovascular Thrombectomy for Anterior Circulation Large Vessel Occlusion Stroke: An Evolution of Trials

The last decade's progress in demonstrating the clinical benefit of endovascular thrombectomy (EVT) in patients with large vessel occlusion stroke has transformed the paradigm of care for these patients. This review presents the milestones in implementing EVT as standard of care, demonstrates the current state of evidence, provides guidance for identifying the candidate patient for EVT, and highlights unsolved and controversial issues. Ongoing trials investigate broadening of EVT indications for patients who present with large core infarction, adjunctive intra-arterial thrombolysis, medium vessel occlusion, low NIHSS, and tandem occlusion.

Reperfusion therapy in acute ischemic stroke: dawn of a new era?

Following the success of recent endovascular trials, endovascular therapy has emerged as an exciting addition to the arsenal of clinical management of patients with acute ischemic stroke (AIS). In this paper, we present an extensive overview of intravenous and endovascular reperfusion strategies, recent advances in AIS neurointervention, limitations of various treatment paradigms, and provide insights on imaging-guided reperfusion therapies. A roadmap for imaging guided reperfusion treatment workflow in AIS is also proposed. Both systemic thrombolysis and endovascular treatment have been incorporated into the standard of care in stroke therapy. Further research on advanced imaging-based approaches to select appropriate patients, may widen the time-window for patient selection and would contribute immensely to early thrombolytic strategies, better recanalization rates, and improved clinical outcomes.

Plasma thrombin-cleaved osteopontin as a potential biomarker of acute atherothrombotic ischemic stroke

We investigated whether thrombin-cleaved osteopontin N-terminal is useful as a blood biomarker of acute atherothrombotic ischemic stroke. Acute ischemic stroke patients were prospectively evaluated with brain magnetic resonance imaging and cardiac evaluations for etiological diagnosis according to the Trial of Org 10172 in Acute Stroke Treatment classification. They were divided into the atherothrombotic and non-atherothrombotic groups. Thrombin-cleaved osteopontin N-terminal, osteopontin, matrix metalloproteinase-9, S100B, C-reactive protein and D-dimer levels were measured from blood samples collected at admission. After excluding patients who met the exclusion criteria or had stroke of other/undetermined etiology, 60 of the 100 patients initially enrolled were included in the final analysis. The ischemic stroke subtypes were atherothrombotic (n=28, 46.7%), cardioembolic (n=19, 31.7%) and lacunar (n=13, 21.7%). Thrombin-cleaved osteopontin N-terminal and matrix metalloproteinase-9 levels were significantly higher in the atherothrombotic than in the non-atherothrombotic group (median (interquartile range): 5.83  (0.0-8.6 ) vs. 0.0  (0.0-3.3) pmol l^-1, P=0.03 and 544   (322-749 ) vs. 343   (254-485) ng ml^-1, P=0.01, respectively). After adjustment for the prevalence of hypertension, diabetes and dyslipidemia, thrombin-cleaved osteopontin N-terminal levels of >5.47 pmol l^-1 (odds ratio, 16.81; 95% confidence interval, 3.53-80.10) and matrix metalloproteinase-9 levels of >605.5 ng ml^-1 (6.59; 1.77-24.60) were identified as independent predictors of atherothrombosis. Within 3 h from stroke onset, only thrombin-cleaved osteopontin N-terminal independently predicted atherothrombosis and thus may add valuable, time-sensitive diagnostic information in the early evaluation of ischemic stroke, especially the atherothrombotic subtype.

State-of-the-art endovascular treatment of acute ischemic stroke

Stroke is the third leading cause of death in the USA. An estimated 795,000 new or recurrent stroke events occur annually, mostly ischemic in nature. Arterial recanalization and subsequent reperfusion performed shortly after symptom onset can help to restore brain function in acute ischemic stroke (AIS). The only treatment currently approved by the United States Food and Drug Administration is intravenous tissue plasminogen activator, administered within 4.5 h of symptom onset. However, this short window often precludes effective intervention. Mechanical neurothrombectomy devices offer many potential advantages over pharmacologic thrombolysis, including more rapid achievement of recanalization, enhanced efficacy in treating large-vessel occlusions, and a potentially lower risk of hemorrhagic events. The goal of this chapter is to describe the state-of-the-art neurothrombectomy devices and stenting techniques for endovascular treatment of acute ischemic stroke, as well as to highlight recent advances in reperfusion therapies. Ongoing clinical trials, some with randomized, controlled designs, are included.

Endovascular procedures versus intravenous thrombolysis in stroke with tandem occlusion of the anterior circulation

PURPOSE

Stroke with tandem occlusion within the anterior circulation presents a lower probability of recanalization and good clinical outcome after intravenous (IV) thrombolysis than stroke with single occlusion. The present study describes the impact of endovascular procedures (EPs) compared with IV thrombolysis alone on recanalization and clinical outcome.

MATERIALS AND METHODS

Thirty patients with symptom onset less than 4.5 hours and tandem occlusion within the anterior circulation were analyzed retrospectively. Recanalization was assessed per Thrombolysis In Cerebral Infarction (TICI) classification on computed tomography, magnetic resonance imaging, or digital subtraction angiography within 24 hours. Infarct size was detected on follow-up imaging as a dichotomized variable, ie, more than one third of the territory of the middle cerebral artery. Clinical outcomes were major neurologic improvement, independent outcome (90-d modified Rankin Scale [mRS] score), symptomatic intracerebral hemorrhage (sICH; per European Cooperative Acute Stroke Study criteria), and death within 7 days.

RESULTS

Patients treated with EPs (n = 14) were significantly younger and had a history of arterial hypertension more frequently than patients treated with IV thrombolysis alone (n = 16). Recanalization (ie, TICI score 2b/3; EP, 64%; IV, 19%; P = .01), major neurologic improvement (EP, 64%; IV, 19%; P = .01), and independent outcome (mRS score ≤ 2; EP, 54% IV, 13%; P = .02) occurred more often in the EP group, whereas infarct sizes greater than one third of the MCA territory (EP, 43%; IV, 81%; P = .03) were observed less often. Rates of sICH (P = .12) and death within 7 days (P = .74) did not differ significantly.

CONCLUSIONS

Higher recanalization rate, smaller infarct volume, and better clinical outcome in the EP group should encourage researchers to include this subgroup of patients in prospective randomized trials comparing IV thrombolysis versus EP in stroke.

[Mechanical recanalization in acute stroke. Torture or choice]

CLINICAL/METHODICAL ISSUE

Stroke is the third most common cause of death in the developed world and the leading cause of disability worldwide. The present demographic development will lead to increased numbers of stroke patients in the future.

STANDARD RADIOLOGICAL METHODS

Patient selection takes place by using various computer tomographic (CT) or magnetic resonance (MR) imaging modalities. For endovascular stroke treatment a modern biplane angiography suite is recommended.

METHODICAL INNOVATIONS

Intra-arterial chemical thrombolysis was shown to be effective in achieving recanalization and improving clinical outcome. Mechanical devices were introduced in the late 1990s and the highly effective stent retriever was recently included.

PERFORMANCE

Mechanical devices allows a recanalization rate of up to 90 % of affected brain vessels.

ACHIEVEMENTS

The advantage of a stent retriever compared to other mechanical devices seems to be an improvement in good clinical outcome.

PRACTICAL RECOMMENDATIONS

Currently, the stent retriever seems to be the definitive first choice in the use of mechanical devices for intra-arterial recanalization treatment in acute ischemic stroke.

The quest for arterial recanalization in acute ischemic stroke-the past, present and the future

Ischemic stroke is one of the major causes of mortality and long-term disability. In the recent past, only very few treatment options were available and a considerable proportion of stroke survivors remained permanently disabled. However, over the last 2 decades rapid advances in acute stroke care have resulted in a corresponding improvement in mortality rates and functional outcomes. In this review, we describe the evolution of systemic thrombolytic agents and various interventional devices, their current status as well as some of the future prospects. We reviewed literature pertaining to acute ischemic stroke reperfusion treatment. We explored the current accepted treatment strategies to attain cerebral reperfusion via intravenous modalities and compare and contrast them within the boundaries of their clinical trials. Subsequently we reviewed the trials for interventional devices for acute ischemic stroke, categorizing them into thrombectomy devices, aspiration devices, clot disruption devices and thrombus entrapment devices. Finally we surveyed several of the alternative reperfusion strategies available. We also shed some light on the controversies surrounding the current strategies of treatment of acute ischemic stroke. Acute invasive interventional strategies continue to improve along with the noninvasive modalities. Both approaches appear promising. We conducted a comprehensive chronological review of the existing treatments as well as upcoming remedies for acute ischemic stroke.

Prediction of Recanalization Trumps Prediction of Tissue Fate

Background and Purpose—

To determine whether infarct core or penumbra is the more significant predictor of outcome in acute ischemic stroke, and whether the results are affected by the statistical method used.

Methods—

Clinical and imaging data were collected in 165 patients with acute ischemic stroke. We reviewed the noncontrast head computed tomography (CT) to determine the Alberta Score Program Early CT score and assess for hyperdense middle cerebral artery. We reviewed CT-angiogram for site of occlusion and collateral flow score. From perfusion-CT, we calculated the volumes of infarct core and ischemic penumbra. Recanalization status was assessed on early follow-up imaging. Clinical data included age, several time points, National Institutes of Health Stroke Scale at admission, treatment type, and modified Rankin score at 90 days. Two multivariate regression analyses were conducted to determine which variables predicted outcome best. In the first analysis, we did not include recanalization status among the potential predicting variables. In the second, we included recanalization status and its interaction between perfusion-CT variables.

Results—

Among the 165 study patients, 76 had a good outcome (modified Rankin score ≤2) and 89 had a poor outcome (modified Rankin score >2). In our first analysis, the most important predictors were age ( P <0.001) and National Institutes of Health Stroke Scale at admission ( P =0.001). The imaging variables were not important predictors of outcome ( P >0.05). In the second analysis, when the recanalization status and its interaction with perfusion-CT variables were included, recanalization status and perfusion-CT penumbra volume became the significant predictors ( P <0.001).

Conclusions—

Imaging prediction of tissue fate, more specifically imaging of the ischemic penumbra, matters only if recanalization can also be predicted.

[Industry-funded therapy studies: what is in the pipeline?]

Several acute stroke trials are underway or have been recently completed. Among the latter are the ICTUS trial and the IST-3 trial. Several other approaches are being tested for thrombolytic therapy among them modern imaging-based patient selection and new thrombolytic agents, such as desmoteplase and tenecteplase. Other strategies include neuroprotection and neurorestoration, biophysical approaches, such as near infrared laser therapy, hemodynamic augmentation and sphenopalatine ganglion stimulation. Mechanical thrombectomy is practiced in many centers although randomized trials are pending and the IMS-3 trial was stopped. This overview will cover the very recently completed and currently recruiting acute ischemic stroke trials.

Developing practice recommendations for endovascular revascularization for acute ischemic stroke

Guidelines have been established for the management of acute ischemic stroke; however, specific recommendations for endovascular revascularization therapy are lacking. Burgeoning investigation of endovascular revascularization therapies for acute ischemic stroke, rapid device development, and a diverse training background of the providers performing the procedures underscore the need for practice recommendations. This review provides a concise summary of the Society of Vascular and Interventional Neurology endovascular acute ischemic stroke roundtable meeting. This document was developed to review current clinical efficacy of pharmacologic and mechanical revascularization therapy, selection criteria, periprocedure management, and endovascular time metrics and to highlight current practice patterns. It therefore provides an outline for the future development of multisociety guidelines and recommendations to improve patient selection, procedural management, and organizational strategies for revascularization therapies in acute ischemic stroke.

Evidence-based changes in devices and methods of endovascular recanalization therapy

The devices and methods of endovascular recanalization therapy (ERT) have been rapidly developed and changed since PROACT II trial. Emerging as a treatment option in addition to intravenous or intra-arterial thrombolysis, mechanical thrombectomy is currently being further developed and investigated as a potential first-line and stand-alone treatment. This review highlights and summarizes the recent clinical series and trials of the available devices and methods of ERT focusing on the multimodal approach.

Endovascular therapy yields significantly superior outcomes for large vessel occlusions compared with intravenous thrombolysis: is it time to randomize?

BACKGROUND AND PURPOSE

We compared outcomes between endovascular (EV) therapy and intravenous (IV) thrombolysis in large vessel strokes.

METHODS

223 patients who had received either IV (n=100) or EV (n=123) therapy were analyzed. Only patients with strokes involving the internal carotid artery terminus (ICA-T, n=45), the middle cerebral artery (M1, n=107) or the bifurcation branches (M2, n=71) were included. The primary endpoint was 3 month outcome based on the modified Rankin Scale (mRS) score, good-outcome defined as mRS ≤2.

RESULTS

The good outcome was 44.7% in the EV group and 26% in the IV group (p=0.003, OR 2.3, 95% CI 1.3 to 4.1). There was no difference in mortality or hemorrhage. For ICA-T occlusions, the good outcome was 27.6% in the EV and 0% in the IV group (p=0.004); for M1 occlusions, 40.6% in the EV versus 10.5% in the IV group (p=0.0006, OR 5.8, 95% CI 1.9 to 18.2); and for M2 occlusions, 76% in the EV versus 47.8% in the IV group (p=0.01, OR 3.5, 95% CI 1.2 to 10.2). For M1 occlusions, the death rate was 27.5% for the EV compared with 57.9% for the IV group (p=0.002, OR 3.6, 95% CI 1.6 to 8.3) with no difference observed in mortality for ICA-T or M2 occlusions. In the univariate analysis, age, National Institutes of Health Stroke Scale score and occlusion site were significant predictors of outcome and mortality (p<0.0001 for all). In the multivariable analysis, EV therapy (p=0.0004, OR 3.9, 95% CI 1.8 to 9) and younger age (p<0.0001, OR 0.96, 95% CI 0.9 to 0.98) were significant independent predictors of good outcome.

CONCLUSIONS

There are significantly higher odds of a favorable outcome with EV compared with IV therapy for large vessel strokes. The data support the rationale of a randomized trial for large vessel occlusions.

Multimodal endovascular management of acute ischemic stroke in patients over 75 years old is safe and effective

Introduction

Greater attention has been directed to endovascular recanalization of acute ischemic stroke in septuagenarians and above.

Technique

A retrospective chart review was conducted to include patients treated for acute ischemic stroke from 2006 to 2012. All patients underwent initial neurological assessment and non-contrast head CT. Patients treated from 2009 to 2012 additionally received emergent CT angiogram and CT perfusion. 51 patients met the clinical and radiographic criteria and underwent multimodal endovascular revascularization for acute ischemic events.

Results

All patients underwent cerebral angiography and met angiographic criteria for endovascular thrombolysis. 34 patients (67%) were older than 80 years of age. 23 patients (45%) received intravenous tissue plasminogen activator prior to admission. Eight (16%) patients underwent stent placement after intra-arterial thrombolysis, 10 (20%) underwent balloon angioplasty and seven (14%) underwent both angioplasty and stent placement. 21 (41%) required only intra-arterial thrombolytics. An improvement in Thrombolysis in Myocardial Infarction score was noted in 34 patients (67%). The average modified Rankin Scale score on discharge was 3.9. Symptomatic intracranial hemorrhage occurred in three patients (6%); none required surgery. One patient (1.9%) had a postoperative retroperitoneal hematoma, which was managed conservatively. Two fatalities resulted from intraoperative vessel rupture (3.9%), with a combined morbidity and mortality of 27.5%.

Conclusions

Multimodal endovascular recanalization of acute ischemic stroke is a relatively safe treatment option in patients older than 75 years of age. Careful patient selection by clinical and radiographic inclusion criteria is necessary for the successful management of stroke in this age group.

Current acute stroke trials and their potential impact on the therapeutic time window

Several trials in acute stroke are underway or have been completed recently. Among the latter, ECASS 3 was a milestone regarding the extension of the rigid 3-h time window out to 4.5 h for intravenous thrombolysis with recombinant tissue plasminogen activator. Several other approaches are being tested for thrombolytic therapy, among them modern imaging-based patient selection of patients and interventional approaches. Other pharmaceutical strategies include neuroprotection, and restoration, biophysical approaches, such as near infrared laser therapy, hemodynamic augmentation, and sphenopalatine ganglion stimulation. This perspective will cover the recently completed and currently recruiting acute stroke trials with respect to their potential role in expanding the therapeutic time window for acute ischemic stroke.

The mid-M1 segment of the middle cerebral artery is a cutoff clot location for good outcome in intravenous thrombolysis

BACKGROUND AND PURPOSE

We studied the impact of the location of the thrombus (internal carotid artery, proximal M1 segment, distal M1 segment, M2 segment, and M3 segment of the middle cerebral artery) in predicting the clinical outcome of patients treated with intravenous thrombolytic therapy (<3 h) in a retrospective cohort.

METHODS

Anterior circulation thrombus was detected with computed tomography angiography in 105 patients. Baseline clinical and radiological information was collected and entered into logistic regression analysis to predict favorable clinical outcome (3-month modified Rankin Scale from 0 to 2 was a primary outcome measure).

RESULTS

Three months after stroke, there was a significant increase in mortality (32% vs. 3%, P < 0.001) and functional dependency (82% vs. 29%, P < 0.001) in patients with internal carotid artery or proximal M1 segment of the middle cerebral artery thrombus compared to a more distal occlusion. In the regression analysis, after adjusting for National Institutes of Health Stroke Scale, age, sex, and onset-to-treatment time, the clot location was an independent predictor of good clinical outcome (P = 0.001) and exhibited dose-response type behavior when moving from a proximal vessel position to a more distal one. When the location was dichotomized, a cutoff between the proximal and the distal M1 segments best differentiated between good and poor clinical outcome (OR = 16.0, 95% CI 3.9-66.2).

CONCLUSIONS

The outcome of acute internal carotid artery or proximal M1 segment of the middle cerebral artery occlusion is generally poor even if treated with intravenous thrombolysis. Alternative revascularization strategies should be considered. Vascular imaging at the admission is required to guide this decision.

Stenting in the treatment of acute ischemic stroke: literature review

Recanalization of acute large artery occlusions is a strong predictor of good outcome. The development of thrombectomy devices resulted in a significant improvement in recanalization rates compared to thrombolytics alone. However, clinical trials and registries with these thrombectomy devices in acute ischemic stroke (AIS) have shown recanalization rates in the range of 40-81%. The last decade has seen the development of nickel titanium self-expandable stents (SES). These stents, in contrast to balloon-mounted stents, allow better navigability and deployment in tortuous vessels and therefore are optimal for the cerebral circulation. SES were initially used for stent-assisted coil embolization of intracranial aneurysms and for treatment of intracranial stenosis. However, a few authors have recently reported feasibility of deployment of SES in AIS. The use of these devices yielded higher recanalization rates compared to traditional thrombectomy devices. Encouraged by these results, retrievable SES systems have been recently used in AIS. These devices offer the advantage of resheathing and retrieving of the stent even after full deployment. Some of these stents can also be detached in case permanent stent placement is needed. Retrievable SES are being used in Europe and currently tested in clinical trials in the United States. We review the recent literature in the use of stents for the treatment of AIS secondary to large vessel occlusion.

Reperfusion Strategies for Acute Ischemic Stroke

Stroke remains a major cause of morbidity and mortality worldwide. Despite preventive measures, effective management strategies are needed to reduce the morbidity and mortality associated with this devastating condition. While the management of hemorrhagic stroke is mostly limited to supportive care, reperfusion strategies in ischemic stroke have been developed and continue to evolve. Conceptually, the pathophysiology of ischemic stroke is similar to that of acute myocardial infarction and the objective of management is similar (ie, to rapidly restore normal flow to reduce permanent damage). It is, therefore, not surprising that the management of acute ischemic stroke includes intravenous (IV) thrombolysis, the only Food and Drug Administration (FDA)-approved strategy at this point. In addition, there are a myriad of emerging endovascular interventional techniques. We review the current literature and discuss some of the technical aspects of endovascular therapy in the setting of acute ischemic stroke.