A trial of imaging selection and endovascular treatment for ischemic stroke

Who does it first? The uptake of medical innovations in the performance of thrombolysis on ischemic stroke patients in Germany: a study based on hospital quality data

Background

Since 2000, systemic thrombolysis has been the only approved curative and causal treatment for acute ischemic stroke. In 2009, the guidelines of the German Society for Neurology were updated and the therapeutic window for performing thrombolysis was extended. The implementation of new therapies is influenced by many factors. We analyzed the factors at the organizational level that influence the implementation of thrombolysis in stroke patients.

Methods

The data published by the majority of German hospitals in their structured quality reports was assessed. We calculated a regression model in order to measure the influence of hospital/department-level characteristics (e.g., teaching status, ownership, location, and number of hospital beds) on the implementation of thrombolysis in 2006 (this is the earliest point in time that can be analyzed on this data basis). In order to measure the effect of the guideline update in 2009 on the thrombolysis rate (TR) change between 2008 and 2010, we performed a Wilcoxon signed-rank test and utilized a regression model.

Results

In 2006, 61.5% of a total of 286 neurology departments performed systemic thrombolysis to treat ischemic strokes. The influencing factors for the use of systemic thrombolysis in 2006 were the existence of a stroke unit (+) and a hospital size of between 500 and 1,000 beds (−). A significant increase of the mean departmental TR (thrombolysis rate) from 6.7% to 9.2% between 2008 and 2010 was observed after the guideline update in 2009. For the departments performing thrombolysis in 2008 and 2010, our analysis could not show any additional influencing factors on a structural level that would explain the TR rise during the period 2008–2010.

Conclusions

Because ischemic stroke patients benefit from systemic thrombolysis, it is necessary to examine possible barriers at the organizational level that hinder the implementation. Our data shows that, organizational factors have an influence on the implementation of thrombolysis. However, the recent guideline update resulted in a TR rise that occurred at all hospitals, regardless of the measured structural conditions, as our analysis could not identify any structural factors that might have influenced the TR after the guideline update.

The Italian Registry of Endovascular Treatment in Acute Stroke: rationale, design and baseline features of patients

Endovascular treatment (ET) showed to be safe in acute stroke, but its superiority over intravenous thrombolysis is debated. As ET is rapidly evolving, it is not clear which role it may deserve in the future of stoke treatments. Based on an observational design, a treatment registry allows to study a broad range of patients, turning into a powerful tool for patients' selection. We report the methodology and a descriptive analysis of patients from a national registry of ET for stroke. The Italian Registry of Endovascular Treatment in Acute Stroke is a multicenter, observational registry running in Italy from 2010. All patients treated with ET in the participating centers were consecutively recorded. Safety measures were symptomatic intracranial hemorrhage, procedural adverse events and death rate. Efficacy measures were arterial recanalization and 3-month good functional outcome. From 2008 to 2012, 960 patients were treated in 25 centers. Median age was 67 years, male gender 57 %. Median baseline NIHSS was 17. The most frequent occlusion site was Middle cerebral artery (46.9 %). Intra-arterial thrombolytics were used in 165 (17.9 %) patients, in 531 (57.5 %) thrombectomy was employed, and 228 (24.7 %) patients received both treatments. Baseline features of this cohort are in line with data from large clinical series and recent trials. This registry allows to collect data from a real practice scenario and to highlight time trends in treatment modalities. It can address unsolved safety and efficacy issues on ET of stroke, providing a useful tool for the planning of new trials.

Endovascular Stroke Therapy Results Improve over Time: The 'Learning Curve' at a New Comprehensive Stoke Center

BACKGROUND

The requirements for a comprehensive stroke center (CSC) include the capability to perform endovascular stroke therapy (EST). EST is a complex process requiring early identification of appropriate patients and effective delivery of intervention. In order to provide prompt intervention for stroke, CSCs have been established away from large academic centers in community-based hospitals. We hypothesized that quantifiable improvements would occur during the first 2 years of a community-based CSC as the processes and personnel evolved. We report the results over time of EST at a new community-based CSC.

METHODS

We have retrospectively analyzed demographic data and outcome metrics of EST from the initiation phase of a new community-based CSC. Data was divided into year 1 and year 2. Statistical analysis (Student's t test and Fisher's exact test) was performed to compare the patient population and outcomes across the two time periods. Outcome variables included the thrombolysis in cerebral infarction (TICI) score, a change in the NIH stroke scale score and the modified Rankin Scale (mRS) score. Analysis of variance (ANOVA) was used to statistically analyze the relationship between population variables and outcome. Computed tomography (CT) angiography and CT perfusion analysis were used to select patients for EST. Approximately half of the patients undergoing EST were excluded from receiving intravenous recombinant tissue plasminogen activator (IV rt-PA) by standard criteria, while the other half showed no sign of improvement following 1 h of IV rt-PA treatment. Mechanical thrombolysis with a stentriever was performed in the majority of cases with or without intra-arterial medication. The majority of treated occlusions were in the middle cerebral artery.

RESULTS

A total of 18 patients underwent EST during year 1 and year 2. A statistically significant increase in good outcomes (mRS score ≤2 at discharge) was seen from year 1 to year 2 (p = 0.05). There were trends towards faster interventions, decreased complications and mortality as well as an improved TICI score from year 1 to year 2. With ANOVA, mortality was statistically correlated with age (p = 0.06), while decreases in the NIH stroke scale (NIHSS) score following EST correlated with decreased mortality (p = 0.01). A higher TICI score was significantly associated with a decreased NIHSS score following EST (p = 0.01).

CONCLUSIONS

At a new community-based CSC, improved outcome occurred from year 1 to year 2, and trends towards decreased mortality, fewer complications, and improved revascularization were observed. Furthermore, the data shows that improvement in NIHSS score after EST is associated with decreased mortality following stroke in this setting, implying a net benefit.

Endovascular therapy for ischemic stroke

The utility of intravenous tissue plasminogen activator (IV t-PA) in improving the clinical outcomes after acute ischemic stroke has been well demonstrated in past clinical trials. Though multiple initial small series of endovascular stroke therapy had shown good outcomes as compared to IV t-PA, a similar beneficial effect had not been translated in multiple randomized clinical trials of endovascular stroke therapy. Over the same time, there have been parallel advances in imaging technology and better understanding and utility of the imaging in therapy of acute stroke. In this review, we will discuss the evolution of endovascular stroke therapy followed by a discussion of the key factors that have to be considered during endovascular stroke therapy and directions for future endovascular stroke trials.

Pathophysiology of acute middle cerebral artery infarct by multimodal computed tomography: A pilot study in Thai patients

AIMS

The purpose of this study was to study pathophysiology of acute middle cerebral artery infarct using multimodal CT and to evaluate the safety and feasibility of this method in our center.

MATERIALS AND METHODS

Patients who had moderate to severe stroke (NIHSS score > 10), suspected of anterior circulation infarct and presented within 4 hours after stroke onset were prospectively included. Multimodal CTs, using low-osmolar contrast agents, were performed in all patients.

RESULTS

Twenty-two patients were included. Mean NIHSS was 16. All patients received intravenous thrombolysis. Favorable outcome was found in nine patients (41%). CTP was unable to identify ischemic lesions in three patients with small subcortical infarct. Most patients (82%) with large middle cerebral artery infarct still had some salvageable brain (penumbra) which partly recovered in a follow-up imaging. Eleven patients (50%) had major artery occlusion. Two patients had creatinine rising within 72 hours.

CONCLUSIONS

Multimodal CT does provide information about status of major artery and the volume of salvageable/infarct brain tissue and is safely and easily applicable in our center.

A randomized trial of intraarterial treatment for acute ischemic stroke

BACKGROUND

In patients with acute ischemic stroke caused by a proximal intracranial arterial occlusion, intraarterial treatment is highly effective for emergency revascularization. However, proof of a beneficial effect on functional outcome is lacking.

METHODS

We randomly assigned eligible patients to either intraarterial treatment plus usual care or usual care alone. Eligible patients had a proximal arterial occlusion in the anterior cerebral circulation that was confirmed on vessel imaging and that could be treated intraarterially within 6 hours after symptom onset. The primary outcome was the modified Rankin scale score at 90 days; this categorical scale measures functional outcome, with scores ranging from 0 (no symptoms) to 6 (death). The treatment effect was estimated with ordinal logistic regression as a common odds ratio, adjusted for prespecified prognostic factors. The adjusted common odds ratio measured the likelihood that intraarterial treatment would lead to lower modified Rankin scores, as compared with usual care alone (shift analysis).

RESULTS

We enrolled 500 patients at 16 medical centers in The Netherlands (233 assigned to intraarterial treatment and 267 to usual care alone). The mean age was 65 years (range, 23 to 96), and 445 patients (89.0%) were treated with intravenous alteplase before randomization. Retrievable stents were used in 190 of the 233 patients (81.5%) assigned to intraarterial treatment. The adjusted common odds ratio was 1.67 (95% confidence interval [CI], 1.21 to 2.30). There was an absolute difference of 13.5 percentage points (95% CI, 5.9 to 21.2) in the rate of functional independence (modified Rankin score, 0 to 2) in favor of the intervention (32.6% vs. 19.1%). There were no significant differences in mortality or the occurrence of symptomatic intracerebral hemorrhage.

CONCLUSIONS

In patients with acute ischemic stroke caused by a proximal intracranial occlusion of the anterior circulation, intraarterial treatment administered within 6 hours after stroke onset was effective and safe. (Funded by the Dutch Heart Foundation and others; MR CLEAN Netherlands Trial Registry number, NTR1804, and Current Controlled Trials number, ISRCTN10888758.).

Emergency and critical care management of acute ischaemic stroke

Ischaemic stroke is a devastating condition that is the leading cause of disability in the USA. Over the last 2 decades, the focus of management has shifted from secondary stroke prevention to acute treatment. Coordinated care starts in the field with the emergency medical service providers and continues in the ambulance and the emergency department through to the intensive care unit. After diagnosis and stabilization, a major goal is reperfusion therapy with intravenous fibrinolytics. Neuroimaging research is focused on improving patient selection, expanding treatment windows, and increasing the safety of therapeutic intervention. The role of adjunctive intra-arterial and mechanical thrombectomy remains undefined, and methods to improve reperfusion using sonolysis and new-generation fibrinolytics are currently investigational. Treatment in the intensive care unit targets prevention of secondary brain injury through optimization of blood pressure, cerebral perfusion, glucose, and temperature management, ventilation, and oxygenation. The most feared complications include malignant cerebral edema and symptomatic hemorrhagic transformation. Decompressive craniectomy is life saving, but questions regarding patient selection and timing remain. Hyperosmolar agents are currently used to mitigate cerebral edema, but newer agents to prevent the formation of cerebral edema at the molecular level are being studied. We outline a practical approach to current emergency and intensive care management based on consensus guidelines and the best available evidence.

Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing CT to recanalization times (ESCAPE) trial: methodology

ESCAPE is a prospective, multicenter, randomized clinical trial that will enroll subjects with the following main inclusion criteria: less than 12 h from symptom onset, age > 18, baseline NIHSS >5, ASPECTS score of >5 and CTA evidence of carotid T/L or M1 segment MCA occlusion, and at least moderate collaterals by CTA. The trial will determine if endovascular treatment will result in higher rates of favorable outcome compared with standard medical therapy alone. Patient populations that are eligible include those receiving IV tPA, tPA ineligible and unwitnessed onset or wake up strokes with 12 h of last seen normal. The primary end-point, based on intention-to-treat criteria is the distribution of modified Rankin Scale scores at 90 days assessed using a proportional odds model. The projected maximum sample size is 500 subjects. Randomization is stratified under a minimization process using age, gender, baseline NIHSS, baseline ASPECTS (8-10 vs. 6-7), IV tPA treatment and occlusion location (ICA vs. MCA) as covariates. The study will have one formal interim analysis after 300 subjects have been accrued. Secondary end-points at 90 days include the following: mRS 0-1; mRS 0-2; Barthel 95-100, EuroQOL and a cognitive battery. Safety outcomes are symptomatic ICH, major bleeding, contrast nephropathy, total radiation dose, malignant MCA infarction, hemicraniectomy and mortality at 90 days.

Infarct growth despite full reperfusion in endovascular therapy for acute ischemic stroke

Aim

To explore the predictors of infarct core expansion despite full reperfusion after intra-arterial therapy (IAT).

Methods

We retrospectively reviewed 604 consecutive patients who underwent IAT for anterior circulation large vessel occlusion acute ischemic stroke in two tertiary centers (2008–2013/2010–2013). Sixty patients selected by MRI or CT perfusion presenting within <24 h of onset with modified Thrombolysis In Cerebral Infarction (mTICI) grade 3 or 2c reperfusion were included. Significant infarct growth (SIG) was defined as infarct expansion >11.6 mL.

Results

Mean age was 67.0±13.7 years, 56% were men. Mean National Institute of Health Stroke Scale (NIHSS) score was 16.2±6.1, time from onset to puncture was 6.8±3.1 h, and procedure length was 1.3±0.6 h. MRI was used for baseline core analysis in 43% of patients. Mean baseline infarct volume was 17.1±19.1 mL, absolute infarct growth was 30.6±74.5 mL, and final infarct volume was 47.7±77.7 mL. Overall, 35% of patients had SIG. Three of 21 patients (14%) treated with stent-retrievers had SIG compared with 14 of 39 (36%) with first-generation devices. Eight of 21 patients (38%) with intravenous tissue plasminogen activator (IV t-PA) had infarct growth compared with 25/39 (64%) without. 23% of patients with SIG had a modified Rankin Scale score ≤2 at 3 months compared with 48% of those without SIG. Multivariate logistic regression indicated that race affected infarct growth. Use of IV t-PA (p=0.03) and stent-retrievers (p=0.03) were independently and inversely correlated with SIG.

Conclusions

Despite full reperfusion, infarct growth is relatively frequent and may explain poor clinical outcomes in this setting. Ethnicity was found to influence SIG. Use of IV t-PA and stent-retrievers were associated with less infarct core expansion.

[Current and future prospects of endovascular treatment for acute ischemic stroke]

Recently, remarkable progress has been made in the field of endovascular treatment, and endovascular treatment for acute ischemic stroke due to large vessel occlusion has been an effective and therapeutic option. However, there is no randomized control trial as to superiority of endovascular treatment for acute ischemic stroke compared to the standard treatment including intravenous rt-PA. Inclusion criteria for the performance of endovascular treatment for acute ischemic stroke will need to be defined more precisely, and high rates of fast recanalization will be needed in future. We expect the evidence that endovascular treatment for acute ischemic stroke due to large vessel occlusion is superior to standard treatment by the detailed images of the brain, more strict indications and novel endovascular devices such as percutaneous transluminal mechanical thrombectomy devices.

White matter ischemic changes in hyperacute ischemic stroke: voxel-based analysis using diffusion tensor imaging and MR perfusion

Background and Purpose—

The purpose of this study was to evaluate changes in fractional anisotropy (FA), as measured by diffusion tensor imaging, of white matter (WM) infarction and hypoperfusion in patients with acute ischemic stroke using a quantitative voxel-based analysis.

Methods—

In this prospective study, diffusion tensor imaging and dynamic susceptibility contrast perfusion sequences were acquired in 21 patients with acute ischemic stroke who presented within 6 hours of symptom onset. The coregistered FA, apparent diffusion coefficient, and dynamic susceptibility contrast time to maximum (Tmax) maps were used for voxel-based quantification using a region of interest approach in the ipsilateral affected side and in the homologous contralateral WM. The regions of WM infarction versus hypoperfusion were segmented using a threshold method. Data were analyzed by regression and ANOVA.

Results—

There was an overall significant mean difference (P<0.001) for the apparent diffusion coefficient, Tmax, and FA values between the normal, hypoperfused, and infarcted WM. The mean±SD of FA was significantly higher (P<0.001) in hypoperfused WM (0.397±0.019) and lower (P<0.001) in infarcted WM (0.313±0.037) when compared with normal WM (0.360±0.020). Regression tree analysis of hypoperfused WM showed the largest mean FA difference at Tmax above versus below 5.4 s with a mean difference of 0.033 (P=0.0096).

Conclusions—

Diffusion tensor imaging-FA was decreased in regions of WM infarction and increased in hypoperfused WM in patients with hyperacute acute ischemic stroke. The significantly increased FA values in the hypoperfused WM with Tmax≥5.4 s are suggestive of early ischemic microstructural changes.

Influence of trial design, heterogeneity and regulatory environment on the results of clinical trials: An appraisal in the context of recent trials on acute stroke intervention

The outcome of randomized controlled trials can vary depending on the eligibility criteria of the patients entering into the trial, as well as the heterogeneity of the eligible population and/or the interventions. If the subject population and/or interventions are heterogeneous, the final outcome of the trial depends on the degree of concordance of effects of the subgroups of interventions on the subgroups of the subject population. The considerations that go into the calculation of sample size and determination of the study stopping rules also would affect the nature of the outcome of the study. In this paper we try to examine these phenomena with respect to the recent trials on endovascular therapy in acute ischemic stroke.

Exposing hidden truncation-related errors in acute stroke perfusion imaging

BACKGROUND AND PURPOSE

The durations of acute ischemic stroke patients' CT or MR perfusion scans may be too short to fully sample the passage of the injected contrast agent through the brain. We tested the potential magnitude of hidden errors related to the truncation of data by short perfusion scans.

MATERIALS AND METHODS

Fifty-seven patients with acute ischemic stroke underwent perfusion MR imaging within 12 hours of symptom onset, using a relatively long scan duration (110 seconds). Shorter scan durations (39.5-108.5 seconds) were simulated by progressively deleting the last-acquired images. CBV, CBF, MTT, and time to response function maximum (Tmax) were measured within DWI-identified acute infarcts, with commonly used postprocessing algorithms. All measurements except Tmax were normalized by dividing by the contralateral hemisphere values. The effects of the scan duration on these hemodynamic measurements and on the volumes of lesions with Tmax of >6 seconds were tested using regression.

RESULTS

Decreasing scan duration from 110 seconds to 40 seconds falsely reduced perfusion estimates by 47.6%-64.2% of normal for CBV, 1.96%-4.10% for CBF, 133%-205% for MTT, and 6.2-8.0 seconds for Tmax, depending on the postprocessing method. This truncation falsely reduced estimated Tmax lesion volume by 71.5 or 93.8 mL, depending on the deconvolution method. "Lesion reversal" (ie, change from above-normal to apparently normal, or from >6 seconds to ≤6 seconds for the time to response function maximum) with increasing truncation occurred in 37%-46% of lesions for CBV, 2%-4% for CBF, 28%-54% for MTT, and 42%-44% for Tmax, depending on the postprocessing method.

CONCLUSIONS

Hidden truncation-related errors in perfusion images may be large enough to alter patient management or affect outcomes of clinical trials.

Fallibility: A New Perspective on the Ethics of Clinical Trial Enrollment

The ethical principle of ‘equipoise’, introduced in 1974, represents the most widely influential justification for the enrollment of patients into randomized clinical trials. However, definitions of equipoise vary, and its terms are not universally accepted. In this paper, we suggest a new way of approaching the ethics of clinical trial enrollment, which we call fallibility. The principle of fallibility argues that all physician opinions are sufficiently uncertain to warrant investigation, and that the ethical justification for any trial becomes a question of its epistemic validity, by which we mean the strength of its hypotheses and methods. The principle of fallibility can be translated into practice through the virtues of humility, skepticism and caring. While we cite recent examples from stroke medicine to demonstrate the limitations of equipoise, we propose that fallibility may offer a more general means of addressing the controversies that arise surrounding randomized controlled trials in many disciplines of medicine.

Effect of the Interaction between Recanalization and Collateral Circulation on Functional Outcome in Acute Ischaemic Stroke

Identification of patients with acute ischaemic stroke who could most benefit from arterial recanalization after endovascular treatment remains an unsettled issue. Although several classifications of collateral circulation have been proposed, the clinical role of collaterals is still debated. We evaluated the effect of the collateral circulation in relation to recanalization as a predictor of clinical outcome. Data were prospectively collected from 103 patients consecutively treated for proximal middle cerebral or internal carotid artery occlusion. The collateral circulation was evaluated with a novel semiquantitative-qualitative score, the Careggi collateral score (CCS), in six grades. Both CCS and recanalization grades (TICI) were analysed in relation to clinical outcome. A statistical analysis was performed to evaluate the effect of interaction between recanalization and collateral circulation on clinical outcome. Out of the 103 patients, 37 (36.3%) had poor collaterals, and 65 (63.7%) had good collaterals. Patients with good collaterals had lower basal National Institute of Health Stroke Scale (NIHSS), more distal occlusion, smaller lesions at 24h CT scan and better functional outcome. After multivariate analysis, the interaction between recanalization and collateral grades was significantly stronger as a predictor of good outcome (OR 6.87, 95% CI 2.11-22.31) or death (OR 4.66, 95%CI 1.48-14.73) compared to the effect of the single variables. Collaterals showed an effect of interaction with the recanalization grade in determining a favourable clinical outcome. Assessment of the collateral circulation might help predict clinical results after recanalization in patients undergoing endovascular treatment for acute ischaemic stroke.

[Endovascular therapy in the treatment of acute ischemic stroke: what the cardiologist should know]

INTRODUCTION

Interventional cardiology procedures are regularly exposed to ischemic neurological complications. IV fibrinolysis is the only approved treatment in ischemic stroke but is very often contraindicated in these situations. Many techniques of interventional neuroradiology (mechanical thrombectomy) have been developed over the past years and are used to treat these patients.

OBSERVATION

We report the case of two patients who were admitted in emergency for ischemic stroke with contraindication to IV fibrinolysis (cardioversion for atrial fibrillation under anticoagulation; 24 hours after carotid surgery). These patients were treated by endovascular thrombectomy procedure.

DISCUSSION

After validation of IV fibrinolysis within 4.5 hours after stroke onset, techniques of mechanical thrombectomy have gradually been developed, either as a complementary treatment or as an alternative in the case of CI to fibrinolysis. These endovascular thrombectomy devices currently allow recanalization of proximal cerebral occlusions, which correlates with a favorable clinical prognosis. A review of the literature is provided, along with a discussion about the techniques currently being improved, their advantages and disadvantages and the selection of patients that can benefit from endovascular procedures.

CONCLUSION

In the case of a sudden occurrence of a neurological deficit during a cardiovascular procedure, a "thrombolysis alert" should be triggered. This will permit the rapid establishment of a clinico-radiological report for selecting stroke patients eligible for a procedure of recanalization by thrombolysis and/or mechanical thrombectomy.

Outcomes following sonothrombolysis in severe acute ischemic stroke: subgroup analysis of the CLOTBUST trial

BACKGROUND

Sonothrombolysis is safe and may increase the likelihood of early recanalization in acute ischemic stroke patients.

AIMS

In preparation of a phase III clinical trial, we contrast the likelihood of achieving a sustained recanalization and functional independence in a post hoc subgroup analysis of patients randomized to transcranial Doppler monitoring plus intravenous tissue plasminogen activator (sonothrombolysis) compared with intravenous tissue plasminogen activator alone in the CLOTBUST trial.

METHODS

We analyzed the data from all randomized acute ischemic stroke patients with pretreatment National Institutes of Health Stroke Scale scores ≥ 10 points and proximal intracranial occlusions in the CLOTBUST trial. We compared sustained complete recanalization rate (Thrombolysis in Brain Ischemia flow grades 4-5) and functional independence (modified Rankin Scale 0-1) at 90 days. Safety was evaluated by the rate of symptomatic intracranial hemorrhage within 72 h of stroke onset.

RESULTS

Of 126 patients, a total of 85 acute ischemic stroke patients met our inclusion criteria: mean age 71 ± 11years, 56% men, median National Institutes of Health Stroke Scale 17 (interquartile range 14-20). Of these patients, 41 (48%) and 44 (52%) were randomized to intravenous tissue plasminogen activator alone and sonothrombolysis, respectively. More patients achieved sustained complete recanalization in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (38·6% vs. 17·1%; P = 0·032). Functional independence at 90 days was more frequently achieved in the sonothrombolysis than in the intravenous tissue plasminogen activator alone group (37·2% vs. 15·8%; P = 0·045). Symptomatic intracranial hemorrhage rate was similar in both groups (4·9% vs. 4·6%; P = 1·00).

CONCLUSIONS

Our results point to a signal of efficacy and provide information to guide the subsequent phase III randomized trial of sonothrombolysis in patients with severe ischemic strokes.

Time to Angiographic Reperfusion in Acute Ischemic Stroke

Background and Purpose—

Our objective was to use decision analytic modeling to compare 2 treatment strategies of intravenous recombinant tissue-type plasminogen activator (r-tPA) alone versus combined intravenous r-tPA/endovascular therapy in a subgroup of patients with large vessel (internal carotid artery terminus, M1, and M2) occlusion based on varying times to angiographic reperfusion and varying rates of reperfusion.

Methods—

We developed a decision model using Interventional Management of Stroke (IMS) III trial data and comprehensive literature review. We performed 1-way sensitivity analyses for time to reperfusion and 2-way sensitivity for time to reperfusion and rate of reperfusion success. We also performed probabilistic sensitivity analyses to address uncertainty in total time to reperfusion for the endovascular approach.

Results—

In the base case, endovascular approach yielded a higher expected utility (6.38 quality-adjusted life years) than the intravenous-only arm (5.42 quality-adjusted life years). One-way sensitivity analyses demonstrated superiority of endovascular treatment to intravenous-only arm unless time to reperfusion exceeded 347 minutes. Two-way sensitivity analysis demonstrated that endovascular treatment was preferred when probability of reperfusion is high and time to reperfusion is small. Probabilistic sensitivity results demonstrated an average gain for endovascular therapy of 0.76 quality-adjusted life years (SD 0.82) compared with the intravenous-only approach.

Conclusions—

In our post hoc model with its underlying limitations, endovascular therapy after intravenous r-tPA is the preferred treatment as compared with intravenous r-tPA alone. However, if time to reperfusion exceeds 347 minutes, intravenous r-tPA alone is the recommended strategy. This warrants validation in a randomized, prospective trial among patients with large vessel occlusions.

Correlation of AOL recanalization, TIMI reperfusion and TICI reperfusion with infarct growth and clinical outcome

OBJECTIVE

To understand how three commonly used measures of endovascular therapy correlate with clinical outcome and infarct growth.

METHODS

Prospectively enrolled patients underwent baseline MRI and started endovascular therapy within 12 h of stroke onset. The final angiogram was given a primary arterial occlusive lesion (AOL) recanalization score (0-3), a Thrombolysis in Myocardial Infarction (TIMI) score (0-3) and a Thrombolysis in Cerebral Infarction (TICI) score (0-3). The scores were dichotomized into poor revascularization (AOL 0-2, TIMI 0-1 and TICI 0-2a) versus good revascularization (AOL 3, TIMI 2-3, TICI 2b-3). Patients were classified according to whether or not they had target mismatch (TMM). Good outcome was defined as a 90-day modified Rankin Scale score of 0-2.

RESULTS

Endovascular treatment was attempted in 100. A good outcome was achieved in 57% of patients with a TICI score of 2b-3 and in 24% of patients with a TICI score of 0-2a (p=0.001). Patients with TIMI scores of 2-3 and an AOL score of 3 had lower rates of good outcome (44% and 47%, respectively), which were not significantly better than those with TIMI scores of 0-1 or AOL scores of 0-2. In patients with TMM, these rates of good outcome improved with all the scoring systems and were significantly better for TIMI and TICI scores. Patients with a TICI score of 2a had rates of good functional outcome and lesion growth which were not different from those with TICI scores of 0-1 but were significantly worse than those with TICI scores of 2b-3.

CONCLUSIONS

TIMI 2-3 and TICI 2b-3 reperfusion scores demonstrated improved outcome in patients with tissue mismatch with a small infarct core and a larger hypoperfused region but AOL scores did not. Patients with a TICI score of 2a had a poorer outcome and more lesion growth than those with TICI scores of 2b-3.

Complications of the endovascular management of acute ischemic stroke

Acute ischemic stroke is a significant source of morbidity and mortality across the globe. Currently, the only US Food and Drug Administration approved medical treatment of acute ischemic stroke is intravascular (IV) alteplase. While IV thrombolysis has been shown to decrease morbidity and mortality from acute ischemic stroke, it is limited in both its efficacy in certain types of stroke, as well as in its generalizability. It has been shown that time to revascularization is one of the most important predictors of outcomes in acute ischemic stroke, and thus clinicians have turned to endovascular options in efforts to improve outcomes from stroke. Direct intra-arterial thrombolysis was one of the first of such efforts to improve efficacy rates and increase the timeline for thrombolytic therapy. More recently, investigators and clinicians have turned to newer endovascular options in attempts to further improve recanalization rates. Many different endovascular techniques have been employed and are growing exponentially in use. Examples include stenting, as well as mechanical thrombectomy with both older-generation devices and newer stent retrieval technology. While the majority of the literature focuses on the effectiveness of different techniques, such as recanalization rates and major overall outcomes such as death and disability, there is very little literature on the complications of the different techniques. The purpose of this article is to review the different forms of endovascular treatment of acute ischemic stroke and their associated complications.

Lessons learnt from recent endovascular stroke trials: finding a way to move forward

The advent of stentrievers provided momentum for endovascular stroke therapy. Hopes were dampened after three randomized trials showed no clear benefit of endovascular therapy. This review discusses the results of these trials results and shortcomings. A detailed discussion will follow on the design, conduct and analysis of current and future endovascular stroke trials. Steps to improve the workflow of acute stroke cases from the time they enter the emergency department until endovascular reperfusion is achieved can significantly shorten the time from onset to successful reperfusion. These factors in addition to using novel approaches to analyze data and minimize delays caused by the consent process are perceived to be sufficient to demonstrate the efficacy of endovascular stroke therapy.

Recanalization and Reperfusion Therapies of Acute Ischemic Stroke: What have We Learned, What are the Major Research Questions, and Where are We Headed?

Two placebo-controlled trials have shown that early administration of intravenous recombinant tissue plasminogen activator (rt-PA) after ischemic stroke improves outcomes up to 4.5 h after symptoms onset; however, six other trials contradict these results. We also know from analysis of the pooled data that benefits from treatment decrease as time from stroke onset to start of treatment increases. In addition to time, another important factor is patient selection through multimodal imaging, combining data from artery status, and salvageable tissue measures. Nonetheless, at the present time randomized controlled trials (RCTs) cannot demonstrate any beneficial outcomes for neuroimaging mismatch selection after 4.5 h from symptoms onset. By focusing on cases of large arterial occlusion, we know that recanalization is crucial, so endovascular treatment is an approach of interest. The use of intra-arterial thrombolysis was tested in two small RCTs that demonstrated clear benefits in terms of higher recanalization and also in clinical outcomes. But a new paradigm of stroke treatment may have begun with mechanical thrombectomy. In this field, Merci devices have been overtaken by fully deployed closed-cell self-expanding stents (stent-retrievers or “stent-trievers”). However, despite the high rate of recanalization achieved with stent-retrievers compared with other recanalization treatments, the use of these devices cannot clearly demonstrate better outcomes. Thus, futile recanalization occurs when successful recanalization fails to improve functional outcome. Recently, three RCTs, namely synthesis, IMS-III, and MR-rescue, have not been demonstrated any clear benefit for endovascular treatment. Most likely, these trials were not adequately designed to prove the superiority of endovascular treatment because they did not use optimal target populations, vascular status was not evaluated in all patients, relatively high rates of patients did not have enough mismatch, time from baseline neuroimaging to recanalization were too long or the devices used are now obsolete relative to stent-retrievers. Several RCTs currently underway are trying to determine whether bridging therapy is more effective than intravenous treatment and if mechanical thrombectomy is more effective than best medical treatment in patients ineligible for intravenous thrombolysis.

Scoring flow restoration in cerebral angiograms after endovascular revascularization in acute ischemic stroke patients

Endovascular revascularization techniques are increasingly used to treat arterial occlusions in patients with acute ischemic stroke. To monitor and communicate treatment results, a valid, reproducible, and clinically relevant, yet easy to use grading scheme of arterial recanalization and tissue reperfusion for digital subtraction angiography is needed. An ideal scoring system would consider the target arterial lesion, the perfusion deficit, and the collateral status before treatment and measure recanalization, reperfusion, early venous shunting, vasospasm, as well as distal embolization after flow restoration. Currently, a variety of different flow restoration scales are in use, including the Thrombolysis in Myocardial Infarction scoring system, the Thrombolysis in Cerebral Infarction score, and the Arterial Occlusive Lesion score, which describe the local recanalization result. These scores are not used homogeneously throughout the literature, are often modified and not fully documented, which make them inept to compare treatment effects across studies. In addition, none of these scores cover all of the above-mentioned aspects, nor are they able to describe satisfactorily all relevant angiographic findings, and data on their reliability and predictive power regarding clinical outcome are sparse. We aimed to review and illustrate the different revascularization scales, discuss their advantages and limitations as well as the available data regarding standardization, reliability testing, and outcome prediction. In addition, we give examples for the use of the scales and show potential pitfalls.

Door-to-puncture: a practical metric for capturing and enhancing system processes associated with endovascular stroke care, preliminary results from the rapid reperfusion registry

Background

In 2011, the Brain Attack Coalition proposed door‐to‐treatment times of 2 hours as a benchmark for patients undergoing intra‐arterial therapy (IAT). We designed the Rapid Reperfusion Registry to capture the percentage of stroke patients who meet the target and its impact on outcomes.

Methods and Results

This is a retrospective analysis of anterior circulation patients treated with IAT within 9 hours of symptom onset. Data was collected from December 31, 2011 to December 31, 2012 at 2 centers and from July 1, 2012 to December 31, 2012 at 7 centers. Short “Door‐to‐Puncture” (D2P) time was hypothesized to be associated with good patient outcomes. A total of 478 patients with a mean age of 68±14 years and median National Institutes of Health Stroke Scale (NIHSS) of 18 (IQR 14 to 21) were analyzed. The median times for IAT delivery were 234 minutes (IQR 163 to 304) for “last known normal‐to‐groin puncture” time (LKN‐to‐GP) and 112 minutes (IQR 68 to 176) for D2P time. The overall good outcome rate was 39.7% for the entire cohort. In a multivariable model adjusting for age, NIHSS, hypertension, diabetes, reperfusion status, and symptomatic hemorrhage, both short LKN‐to‐GP (OR 0.996; 95% CI [0.993 to 0.998]; P<0.001) and short D2P times (OR 0.993, 95% CI [0.990 to 0.996]; P<0.001) were associated with good outcomes. Only 52% of all patients in the registry achieved the targeted D2P time of 2 hours.

Conclusions

The time interval of D2P presents a clinically relevant time frame by which system processes can be targeted to streamline the delivery of IAT care nationally. At present, there is much opportunity to enhance outcomes through reducing D2P.

Evolution of endovascular mechanical thrombectomy for acute ischemic stroke

Acute ischemic stroke (AIS) is a common medical problem associated with significant morbidity and mortality worldwide. A small proportion of AIS patients meet eligibility criteria for intravenous thrombolysis (IVT) with recombinant tissue plasminogen activator, and its efficacy for large vessel occlusion is poor. Therefore, an increasing number of patients with AIS are being treated with endovascular mechanical thrombectomy when IVT is ineffective or contraindicated. Rapid advancement in catheter-based and endovascular device technology has led to significant improvements in rates of cerebral reperfusion with these devices. Stentrievers and modern aspiration catheters have now surpassed earlier generation devices in the degree and rapidity of revascularization. This progress has been achieved with no concurrent increase in risk of major complications or mortality, both when used alone or in combination with IVT. The initial randomized controlled trials comparing endovascular therapy to IVT for AIS failed to show superior outcomes with endovascular treatment, but key limitations of each trial may limit the significance of these results to current practice. While endovascular devices and operator experience continue to evolve, we are optimistic that this will be accompanied by improvements in patient outcomes. This review highlights the major endovascular devices used in current practice and the trials which have investigated their efficacy.

Intravenous thrombolysis for acute ischemic stroke

Intravenous thrombolysis (IVT) with alteplase remains the standard treatment for acute ischemic stroke. Although IVT can be started up to 4.5 hours after symptoms' onset, it is all the more effective and safe when started early. It allows a 10% absolute reduction in the risk of handicap or death at 3 months, despite a 2-7% risk of symptomatic intracranial hemorrhage. Current research efforts involve firstly trying to treat a larger proportion of patients by overcoming some of the contraindications to IVT and secondly assessing combined or alternative treatments to achieve a higher early recanalization rate.

Reducing door-to-puncture times for intra-arterial stroke therapy: a pilot quality improvement project

BACKGROUND

Delays to intra-arterial therapy (IAT) lead to worse outcomes in stroke patients with proximal occlusions. Little is known regarding the magnitude of, and reasons for, these delays. In a pilot quality improvement (QI) project, we sought to examine and improve our door-puncture times.

METHODS AND RESULTS

For anterior-circulation stroke patients who underwent IAT, we retrospectively calculated in-hospital time delays associated with various phases from patient arrival to groin puncture. We formulated and then implemented a process change targeted to the phase with the greatest delay. We examined the impact on time to treatment by comparing the pre- and post-QI cohorts. One hundred forty-six patients (93 pre- vs. 51 post-QI) were analyzed. In the pre-QI cohort (ie, sequential process), the greatest delay occurred from imaging to the neurointerventional (NI) suite ("picture-suite": median, 62 minutes; interquartile range [IQR], 40 to 82). A QI measure was instituted so that the NI team and anesthesiologist were assembled and the suite set up in parallel with completion of imaging and decision making. The post-QI (ie, parallel process) median picture-to-suite time was 29 minutes (IQR, 21 to 41; P<0.0001). There was a 36-minute reduction in median door-to-puncture time (143 vs. 107 minutes; P<0.0001). Parallel workflow and presentation during work hours were independent predictors of shorter door-puncture times.

CONCLUSIONS

In-hospital delays are a major obstacle to timely IAT. A simple approach for achieving substantial time savings is to mobilize the NI and anesthesia teams during patient evaluation and treatment decision making. This parallel workflow resulted in a >30-minute (25%) reduction in median door-to-puncture times.

Collateral flow as causative of good outcomes in endovascular stroke therapy

BACKGROUND

Endovascular reperfusion techniques are a promising intervention for acute ischemic stroke (AIS). Prior studies have identified markers of initial injury (arrival NIH stroke scale (NIHSS) or infarct volume) as predictive of outcome after these procedures. We sought to define the role of collateral flow at the time of presentation in determining the extent of initial ischemic injury and its influence on final outcome.

METHODS

Demographic, clinical, laboratory, and radiographic data were prospectively collected on a consecutive cohort of patients who received endovascular therapy for acute cerebral ischemia at a single tertiary referral center from September 2004 to August 2010.

RESULTS

Higher collateral grade as assessed by the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grading scheme on angiography at the time of presentation was associated with improved reperfusion rates after endovascular intervention, decreased post-procedural hemorrhage, smaller infarcts on presentation and discharge, as well as improved neurological function on arrival to the hospital, discharge, and 90 days later. Patients matched by vessel occlusion, age, and time of onset demonstrated smaller strokes on presentation and better functional and radiographic outcome if found to have superior collateral flow. In multivariate analysis, lower collateral grade independently predicted higher NIHSS on arrival.

CONCLUSIONS

Improved collateral flow in patients with AIS undergoing endovascular therapy was associated with improved radiographic and clinical outcomes. Independent of age, vessel occlusion and time, in patients with comparable ischemic burdens, changes in collateral grade alone led to significant differences in initial stroke severity as well as ultimate clinical outcome.

Reperfusion therapies of acute ischemic stroke: potentials and failures

Over the past 20 years, clinical research has focused on the development of reperfusion therapies for acute ischemic stroke (AIS), which include the use of systemic intravenous thrombolytics (alteplase, desmoteplase, or tenecteplase), the augmentation of systemic intravenous recanalization with ultrasound, the bridging of intravenous with intra-arterial thrombolysis, the use of multi-modal approaches to reperfusion including thrombectomy and thromboaspiration with different available retrievers. Clinical trials testing these acute reperfusion therapies provided novel insight regarding the comparative safety and efficacy, but also raised new questions and further uncertainty on the field. Intravenous alteplase (tPA) remains the fastest and easiest way to initiate acute stroke reperfusion treatment, and should continue to be the first-line treatment for patients with AIS within 4.5 h from onset. The use of tenecteplase instead of tPA and the augmentation of systemic thrombolysis with ultrasound are both novel therapeutical modalities that may emerge as significant options in AIS treatment. Endovascular treatments for AIS are rapidly evolving due to technological advances in catheter-based interventions and are currently emphasizing speed in order to result in timely restoration of perfusion of still-salvageable, infarcted brain tissue, since delayed recanalization of proximal intracranial occlusions has not been associated with improved clinical outcomes. Comprehensive imaging protocols in AIS may enable better patient selection for endovascular interventions and for testing multi-modal combinatory strategies.

Endovascular intervention for acute ischemic stroke in light of recent trials

Three recently published trials, MR RESCUE, IMS III, and SYNTHESIS Expansion, evaluating the efficacy and safety of endovascular treatment of acute ischemic stroke have generated concerns about the future of endovascular approach. However, the tremendous evolution that imaging and endovascular treatment modalities have undergone over the past several years has raised doubts about the validity of these trials. In this paper, we review the role of endovascular treatment strategies in acute ischemic stroke and discuss the limitations and shortcomings that prevent generalization of the findings of recent trials. We also provide our experience in endovascular treatment of acute ischemic stroke.

Alteplase in acute ischemic stroke: putting the guidelines into practice

Intravenous recombinant tissue plasminogen activator (rt-PA or alteplase) is the only approved medical intervention for treatment of acute ischemic stroke within the first hours of symptom onset. In this article, we review the preliminary studies of rt-PA in acute ischemic stroke that led to US FDA approval of its use within 3 h of symptom onset. The studies on rt-PA for use beyond 3 h of symptom onset and future reperfusion therapies are discussed. Overviews of the clinical presentation and treatment of acute ischemic stroke and stroke systems of care are described.

Neuroanesthesiology update

We review topics pertinent to the perioperative care of patients with neurological disorders. Our review addresses topics not only in the anesthesiology literature, but also in basic neurosciences, critical care medicine, neurology, neurosurgery, radiology, and internal medicine literature. We include literature published or available online up through December 8, 2013. As our review is not able to include all manuscripts, we focus on recurring themes and unique and pivotal investigations. We address the broad topics of general neuroanesthesia, stroke, traumatic brain injury, anesthetic neurotoxicity, neuroprotection, pharmacology, physiology, and nervous system monitoring.

Evolution of practice during the Interventional Management of Stroke III Trial and implications for ongoing trials

BACKGROUND AND PURPOSE

We explored changes in the patient population and practice of endovascular therapy during the course of the Interventional Management of Stroke (IMS) III Trial.

METHODS

Changes in baseline characteristics, use of baseline CT angiography, treatment times and specifics, and outcomes were compared between the first 4 protocols and the fifth and final protocol.

RESULTS

Compared with subjects treated in the first 4 protocol versions (n=610), subjects treated in fifth and final protocol (n=46) were older (75 versus 68 years, P<0.0002) and less likely to have a pretreatment Rankin of 0 (76% versus 89%, P=0.01), were more likely to have a pretreatment CT angiography (65% versus 45%, P=0.009), had quicker median times in the endovascular arm from onset to start of intra-arterial therapy (209 versus 250 minutes, P=0.002) and to reperfusion (269 versus 344 minutes, P<0.0001), had a higher mean dose of total tissue-type plasminogen activator in the endovascular arm (74.0 versus 63.7 mg, P<0.0001), and were less likely to receive intra-arterial tissue-type plasminogen activator as part of the endovascular procedure (16% versus 44%, P=0.015). There were no significant differences in functional and safety outcomes between subjects treated in the 2 treatments arms in either the first 4 protocols or fifth protocol although the small sample size in the fifth protocol provided limited power.

CONCLUSIONS

Endovascular technology and diagnostic approaches to acute stroke patients changed substantially during the IMS III Trial. Efforts to decrease the time to delivery of endovascular therapy were successful.

Imaging Selection in Ischemic Stroke: Feasibility of Automated CT-Perfusion Analysis

Background

Advanced imaging may refine patient selection for ischemic stroke treatment but delays to acquire and process the imaging have limited implementation.

Aims

We examined the feasibility of imaging selection in clinical practice using fully automated software in the EXTEND trial program.

Methods

CTP and perfusion-diffusion MRI data were processed using fully-automated software to generate a yes/no ‘mismatch’ classification that determined eligibility for trial therapies. The technical failure/mismatch classification error rate and time to image and treat with CT vs. MR-based selection were examined.

Results

In a consecutive series of 776 patients from five sites over six-months the technical failure rate of CTP acquisition/processing (uninterpretable maps) was 3·4% (26/776, 95%CI 2·2–4·9%). Mismatch classification was overruled by expert review in an additional 9·0% (70/776, 95%CI 7·1–11·3%) due to artifactual ‘perfusion lesion’. In 154 consecutive patients at one site, median additional time to acquire CTP after noncontrast CT was 6·5 min. Subsequent RAPID processing time varied from 3–10 min across 20 trial centers (median 5 min 20 s). In the EXTEND trial, door-to-needle times in patients randomized on the basis of CTP ( n = 47) were median 78 min shorter than MRI-selected ( n = 16) patients ( P < 0·001).

Conclusions

Automated CTP-based mismatch selection is rapid, robust in clinical practice, and associated with faster treatment decisions than MRI. This technological advance has the potential to improve the standardization and reproducibility of interpretation of advanced imaging and extend use to practice settings beyond highly specialized academic centers.