A trial of imaging selection and endovascular treatment for ischemic stroke

Modern interventional management of stroke

Acute ischemic stroke continues to be one of the leading causes of disability and death and is a financial burden to an already taxed health care system. Much research and investigation has been carried out over the past decade on various recanalization devices aimed at restoring cerebral blood flow. Despite the rapidly improving technical abilities of these devices, it has been difficult to demonstrate corresponding improved clinical outcomes. This article will describe the application of the most recent generation of these devices and briefly discuss the ongoing discrepancy between these technical achievements and stroke outcomes.

Angiographic outcome of endovascular stroke therapy correlated with MR findings, infarct growth, and clinical outcome in the DEFUSE 2 trial

BACKGROUND

DEFUSE 2 demonstrated that patients with magnetic resonance imaging mismatch had a favorable clinical response to tissue reperfusion assessed by magnetic resonance imaging. This study reports the endovascular results and correlates angiographic reperfusion with clinical and imaging outcomes.

METHODS

Prospectively enrolled ischemic stroke patients underwent baseline magnetic resonance imaging and started endovascular therapy within 12 h of onset. Patients were classified as either target mismatch or no target mismatch using magnetic resonance imaging. The pre- and postprocedure angiogram was evaluated to determine thrombolysis in cerebral infarction scores. Favorable clinical response was determined at day 30, and good functional outcome was defined as a modified Rankin Scale 0-2 at day 90.

RESULTS

One-hundred patients had attempted endovascular treatment. At procedure end, 23% were thrombolysis in cerebral infarction 0-1, 31% thrombolysis in cerebral infarction 2A, 28% thrombolysis in cerebral infarction 2B, and 18% thrombolysis in cerebral infarction 3. More favorable thrombolysis in cerebral infarction-reperfusion scores were associated with greater magnetic resonance imaging reperfusion (P<0·001). thrombolysis in cerebral infarction scores correlated with 30-day favorable clinical response (P=0·041) and 90-day modified Rankin Scale 0-2 (P=0·008). These correlations were significant for target mismatch patients at 30 days (P=0·034) and 90 days (P=0·003). Infarct growth was strongly associated with poorer thrombolysis in cerebral infarction scores in target mismatch patients (P<0·001). Patients with thrombolysis in cerebral infarctionnfarction 2A reperfusion had less magnetic resonance imaging reperfusion (P=0·004) and poorer clinical outcome at 90 days (P=0·01) compared with thrombolysis in cerebral infarction 2B-3 patients.

CONCLUSION

Thrombolysis in cerebral infarction reperfusion following endovascular therapy for ischemic stroke is highly correlated with magnetic resonance imaging reperfusion, infarct growth, and clinical outcome.

Perfusion-based selection for endovascular reperfusion therapy in anterior circulation acute ischemic stroke

BACKGROUND AND PURPOSE

Controversy exists about the role of perfusion imaging in patient selection for endovascular reperfusion therapy in acute ischemic stroke. We hypothesized that perfusion imaging versus noncontrast CT- based selection would be associated with improved functional outcomes at 3 months.

MATERIALS AND METHODS

We reviewed consecutive patients with anterior circulation strokes treated with endovascular reperfusion therapy within 8 hours and with baseline NIHSS score of ≥8. Baseline clinical data, selection mode (perfusion versus NCCT), angiographic data, complications, and modified Rankin Scale score at 3 months were collected. Using multivariable logistic regression, we assessed whether the mode of selection for endovascular reperfusion therapy (perfusion-based versus NCCT-based) was independently associated with good outcome.

RESULTS

Two-hundred fourteen patients (mean age, 67.2 years; median NIHSS score, 18; MCA occlusion 74% and ICA occlusion 26%) were included. Perfusion imaging was used in 76 (35.5%) patients (39 CT and 37 MR imaging). Perfusion imaging-selected patients were more likely to have good outcomes compared with NCCT-selected patients (55.3 versus 33.3%, P = .002); perfusion selection by CT was associated with similar outcomes as that by MR imaging (CTP, 56.; MR perfusion, 54.1%; P = .836). In multivariable analysis, CT or MR perfusion imaging selection remained strongly associated with good outcome (adjusted OR, 2.34; 95% CI, 1.22-4.47), independent of baseline severity and reperfusion.

CONCLUSIONS

In this multicenter study, patients with acute ischemic stroke who underwent perfusion imaging were more than 2-fold more likely to have good outcomes following endovascular reperfusion therapy. Randomized studies should compare perfusion imaging with NCCT imaging for patient selection for endovascular reperfusion therapy.

Developing precision stroke imaging

Stroke experts stand at the cusp of a unique opportunity to advance the care of patients with cerebrovascular disorders across the globe through improved imaging approaches. NIH initiatives including the Stroke Progress Review Group promotion of imaging in stroke research and the newly established NINDS Stroke Trials network converge with the rapidly evolving concept of precision medicine. Precision stroke imaging portends the coming shift to individualized approaches to cerebrovascular disorders where big data may be leveraged to identify and manage stroke risk with specific treatments utilizing an improved neuroimaging infrastructure, data collection, and analysis. We outline key aspects of the stroke imaging field where precision medicine may rapidly transform the care of stroke patients in the next few years.

Acute ischaemic stroke outcomes following mechanical thrombectomy in the elderly versus their younger counterpart: a retrospective cohort study

OBJECTIVES

Many physicians debate the efficacy of mechanical thrombectomy for ischaemic stroke, but most agree that to establish potential benefit, patient selection must be examined further. People >80 years are a growing population of patients with ischaemic stroke but are largely excluded from clinical trials. The benefit of thrombectomy for them may be greatly reduced due to diminishing neuroplasticity and a larger number of medical comorbidities. To address this knowledge gap, we examined clinical and economic outcomes after mechanical thrombectomy in the ischaemic stroke population from the Nationwide Inpatient Sample. Our null hypotheses were that elderly patients (>80 years) would have a similar rate of inpatient mortality in comparison to their younger counterparts and incur a similar economic expense.

DESIGN

Retrospective cohort study.

SETTING

A 20% stratified sample of US community hospitals within the Nationwide Inpatient Sample.

PARTICIPANTS

All patients from 2008 to 2010 with a primary diagnosis of ischaemic stroke that received mechanical thrombectomy were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was inpatient mortality. Secondary outcomes included hospital charges and length of stay.

RESULTS

Less than 1% of all ischaemic stroke cases (9300) were treated with mechanical thrombectomy. Of these, 18% involved patients over 80 years of age. The odds of inpatient mortality in elderly patients treated with mechanical thrombectomy were approximately twice that of their younger counterparts (OR1.993, p < 0.001). The elderly experienced no significant difference in hospital charges (p=0.105) and length of stay (p=0.498).

CONCLUSIONS

The odds of inpatient mortality after mechanical thrombectomy in patients over 80 years of age were twice that of their younger counterparts. This is consistent with the overall worse prognosis seen in the natural history of this age group. Studies to better identify patients that would benefit from endovascular mechanical thrombectomy may improve outcomes and reduce the gap currently observed in age stratifications.

Collateral lessons from recent acute ischemic stroke trials

Numerous acute ischemic stroke trials have recently published detailed results, providing an opportunity to consider the role of collaterals in stroke pathophysiology and their influential effect on patient outcomes. Safety and Efficacy of NeuroFlo Technology in Ischemic Stroke (SENTIS), the largest randomized controlled trial of device therapy to date, tested the potential augmentation of collateral perfusion. SYNTHESIS Expansion, Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE), and Interventional Management of Stroke (IMS) III chronicled the saga of endovascular therapy trialed against medical treatment for acute ischemic stroke. These recent randomized studies, however, largely neglect current device technology available for endovascular therapy as advanced by the TREVO2 and SOLITAIRE™(TM) FR With the Intention For Thrombectomy (SWIFT) studies. Such exhaustive efforts in recent trials have failed to introduce a new treatment for stroke that unequivocally improves patient outcomes. Collateral perfusion is widely recognized to vary across individuals in any population and exerts a dramatic effect on baseline variables including the time course of ischemic injury, stroke severity, imaging findings, and therapeutic opportunities. Similarly, collaterals have been recognized to influence recanalization, reperfusion, hemorrhagic transformation, and subsequent neurological outcomes after stroke. Collateral lessons may be gleaned from these trials, to expand consideration of overall study results and perhaps most importantly, alter ongoing and new trials in development. Detailed analyses of available information on collaterals from these trials demonstrate that collaterals may be more influential than the choice of treatment modality or intervention.

Successful recanalization with multimodality endovascular interventional therapy in acute ischemic stroke

Stroke is an important cause of death and disability in adults. However, effective treatments for patients with acute ischemic stroke are limited. Intravenous recombinant tissue plasminogen activator (iv rtPA) within 4.5 h after onset has been approved as a standard treatment for patients with acute ischemic stroke. However, due to time constraints, less than one percent of acute ischemic stroke patients in Thailand are able to obtain iv rtPA. Although endovascular interventional therapy has not yet been approved as standard treatment in acute ischemic stroke, it is the one of the potentially effective treatment options. There are several reliable methods of endovascular therapy for acute ischemic stroke patients. Endovascular interventional therapy has rarely been done in Thailand. We report seven patients with successful recanalization after endovascular treatment in acute large vessel stroke from a single stroke center in Thailand. Patient screening and selection with multimodal imaging protocol and multimodality methods of endovascular interventional therapy are described.

Endovascular treatment of acute ischemic stroke: Honolulu shock and thereafter

Recently, use of mechanical clot retrievers for acute stroke has gradually spread. However, 3 recent randomized controlled trials failed to show superiority of endovascular treatment compared to intravenous recombinant tissue plasminogen activator (IV rt-PA) alone or standard care. On the other hand, a Japanese nationwide survey demonstrated the efficacy of endovascular treatment in the IV rt-PA failed and ineligible patients, especially with the proximal artery occlusion such as the internal carotid artery. Earlier initiation and higher reperfusion of endovascular treatment seemed to be the main reason for the better result in this survey compared with the reported randomized studies. Because next-generation devices such as stent retrievers have been shown to provide better effects in terms of clinical outcomes compared with the Merci retriever, the efficacy of endovascular treatment is expected to be confirmed again by randomized controlled trials in the near future.

Predictors of Outcome following Stroke due to Isolated M2 Occlusions

Background

Factors influencing outcome after cerebral artery occlusion are not completely understood. Although it is well accepted that the site of arterial occlusion critically influences outcome, the majority of studies investigating this issue has focused on proximal large artery occlusion. To gain a better understanding of factors influencing outcome after distal large artery occlusion, we sought to assess predictors of outcome following isolated M2 middle cerebral artery occlusion infarcts.

Methods

We retrospectively analyzed patients with isolated acute M2 occlusion admitted to a single academic center from January 2010 to August 2012. Baseline clinical, laboratory imaging, and outcome data were assessed from a prospectively collected database. Factors associated with a modified Rankin Scale (mRS) score ≤2 in univariable analyses (p < 0.05) were entered into multivariable logistic regression analysis. The Admission National Institutes of Health Stroke Scale (aNIHSS) score, age, and infarct volume were also entered as dichotomized variables. Receiver operating characteristic curves were plotted to determine the optimal aNIHSS score, infarct volume, and age cut points predicting an mRS score ≤2. Optimal thresholds were determined by maximizing the Youden index. Respective multivariable logistic regression analyses were used to identify independent predictors of a good 90-day outcome (mRS score ≤2; primary analysis) as well as 90-day mortality (secondary outcome).

Results

90 patients with isolated M2 occlusion were included in the final analyses. Of these, 69% had a good 90-day outcome which was associated with age <80 years (p = 0.007), aNIHSS <10 (p = 0.002), and infarct volume ≤26 ml (p < 0.001). Notably, 20% of patients (64% of those with a poor outcome) had died by 90 days. Secondary analysis for 90-day mortality was performed. This analysis indicated that infarct volume >28 ml (OR 11.874, 95% CI 2.630-53.604, p = 0.001), age >80 years (OR 4.953, 95% CI 1.087-22.563, p = 0.039), need for intubation (OR 7.788, 95% CI 1.072-56.604), and history of congestive heart failure (OR 5.819, 95% CI 1.140-29.695) were independent predictors of 90-day mortality (20% of all included patients).

Conclusion

While the majority of patients with isolated M2 occlusion stroke has a good 90-day outcome, a substantial proportion of subjects dies by 90 days, as identified by a unique subset of predictors. The knowledge gained from our study may lead to an improvement in the prognostic accuracy, clinical management, and resource utilization in this patient population.

Diffusion-weighted imaging volume as the best predictor of the diffusion-perfusion mismatch in acute stroke patients within 8 hours of onset

BACKGROUND

Diagnostic accuracies of standard NCCT, CTA, CTA-SI, FLAIR, and DWI to detect the diffusion-perfusion mismatch (DPM) were compared.

METHODS

Stroke patients considered for endovascular therapy within 8 hours of onset were enrolled. DPM was defined as at least 160% mismatch between DWI and PWI volume.

RESULTS

DPM was seen in 35 (71%) of 49 patients. ASPECTS on NCCT, CTA-SI, and DWI was 9 (8-9), 8 (6-9), and 7 (5-9) in mismatch group, and 6 (4-9), 6 (2-7), 5 (2-6) in nonmismatch group, respectively (P = .027, .006, and .001). Ischemic volume on CTA-SI and DWI was 4.6 (.2-13.0) cm(3) and 21.5 (9.7-44.0) cm(3) in mismatch group, and 61.5 (6.6-101.1) cm(3) and 94.9 (45.7-139.8) cm(3) in nonmismatch group (P = .003 and <.001). Significant collateralization on CTA-SI and FLAIR was seen in 80% and 88% in mismatch group, and 42% and 58% in nonmismatch group (P = .026 and .039). Odds ratios (95% CI) of DWI volume of ≤ 70 cm(3) to predict the mismatch was 30.17 (2.06-442.41) after adjusting for ASPECTSs on NCCT, CTA-SI, and DWI, 44.90 (2.75-732.73) for ischemic volume on CTA-SI, and 42.80 (3.05-601.41) for significant collateralization on CTA-SI and FLAIR (P = .013, .008, and .005).

CONCLUSIONS

DWI volume was the best predictor of DPM.

Outcomes of a contemporary cohort of 536 consecutive patients with acute ischemic stroke treated with endovascular therapy

BACKGROUND AND PURPOSE

We sought to assess outcomes after endovascular treatment/therapy of acute ischemic stroke, overall and by subgroups, and looked for predictors of outcome.

METHODS

We used data from a mandatory, population-based registry that includes external monitoring of completeness, which assesses reperfusion therapies for consecutive patients with acute ischemic stroke since 2011. We described outcomes overall and by subgroups (age ≤ or >80 years; onset-to-groin puncture ≤ or >6 hours; anterior or posterior strokes; previous IV recombinant tissue-type plasminogen activator or isolated endovascular treatment/therapy; revascularization or no revascularization), and determined independent predictors of good outcome (modified Rankin Scale score ≤2) and mortality at 3 months by multivariate modeling.

RESULTS

We analyzed 536 patients, of whom 285 received previous IV recombinant tissue-type plasminogen activator. Overall, revascularization (modified Thrombolysis In Cerebral Infarction scores, 2b and 3) occurred in 73.9%, 5.6% developed symptomatic intracerebral hemorrhages, 43.3% achieved good functional outcome, and 22.2% were dead at 90 days. Adjusted comparisons by subgroups systematically favored revascularization (lower proportion of symptomatic intracerebral hemorrhages and death rates and higher proportion of good outcome). Multivariate analyses confirmed the independent protective effect of revascularization. Additionally, age >80 years, stroke severity, hypertension (deleterious), atrial fibrillation, and onset-to-groin puncture ≤6 hours (protective) also predicted good outcome, whereas lack of previous disability and anterior circulation strokes (protective) as well as and hypertension (deleterious) independently predicted mortality.

CONCLUSIONS

This study reinforces the role of revascularization and time to treatment to achieve enhanced functional outcomes and identifies other clinical features that independently predict good/fatal outcome after endovascular treatment/therapy.

Impact of a comprehensive stroke centre on the care of patients with acute ischaemic stroke due to cervical artery dissection

INTRODUCTION

Cervical artery dissection (CAD) is the cause of 2% to 3% of ischaemic strokes and 10% to 25% of the ischaemic strokes in young people. Our objective is to evaluate whether implementation of a comprehensive stroke centre (CSC) improves the diagnosis and modifies the prognosis of patients with acute stroke due to CAD.

PATIENTS AND METHODS

Retrospective study of a registry of consecutive patients with acute stroke due to CAD. They were classified according to the period of care at our centre: pre-CSC (October 2004-March 2008, 42 months) or post-CSC (April 2008-June 2012, 51 months). We compared baseline characteristics, methods of diagnosis, treatment and outcome of these patients in both periods.

RESULTS

Nine patients were diagnosed with CAD in pre-CSC and 26 in post-CSC, representing 0.8% and 2.1% of all ischaemic strokes treated in each period, respectively. The diagnosis of CAD was made within the first 24 hours in 42.3% of the patients in post-CSC versus 0% in pre-CSC, by using urgent cerebral angiography as a diagnostic test in 46.2% of cases in the second period compared to 0% in the first. Both severity of stroke (median NIHSS score 11 vs. 3, P=.014) and time to neurological care (265 min vs 148, P=.056) were higher in the post-CSC period. Endovascular treatment was performed in 34.3%, and all treatments were post-CSC. The functional outcome was comparable for both periods.

CONCLUSIONS

Implementation of a CSC increases the frequency of the diagnosis of CAD, as well as the treatment options for these patients in the acute phase of stroke.

Multi-delay arterial spin labeling perfusion MRI in moyamoya disease--comparison with CT perfusion imaging

OBJECTIVES

To present a multi-delay pseudo-continuous ASL (pCASL) protocol that offers simultaneous measurements of cerebral blood flow (CBF) and arterial transit time (ATT), and to study correlations between multi-delay pCASL and CT perfusion in moyamoya disease.

METHODS

A 4 post-labeling delay (PLD) pCASL protocol was applied on 17 patients with moyamoya disease who also underwent CT perfusion imaging. ATT was estimated using the multi-delay protocol and included in the calculation of CBF. ASL and CT perfusion images were rated for lesion severity/conspicuity. Pearson correlation coefficients were calculated across voxels between the two modalities in grey and white matter of each subject respectively and between normalized mean values of ASL and CT perfusion measures in major vascular territories.

RESULTS

Significant associations between ASL and CT perfusion were detected using subjective ratings, voxel-wise analysis in grey and white matter and region of interest (ROI)-based analysis of normalized mean perfusion. The correlation between ASL CBF and CT perfusion was improved using the multi-delay pCASL protocol compared to CBF acquired at a single PLD of 2 s (P < 0.05).

CONCLUSIONS

There is a correlation between perfusion data from ASL and CT perfusion imaging in patients with moyamoya disease. Multi-delay ASL can improve CBF quantification, which could be a prognostic imaging biomarker in patients with moyamoya disease.

KEY POINTS

• Simultaneous measurements of CBF and ATT can be achieved using multi-delay pCASL. • Multi-delay ASL was compared with CT perfusion in patients with moyamoya disease. • Statistical analyses showed significant associations between multi-delay ASL and CT perfusion. • Multi-delay ASL can improve CBF quantification in moyamoya disease.

Systematic review, critical appraisal, and analysis of the quality of economic evaluations in stroke imaging

BACKGROUND AND PURPOSE

This study reviews the quality of economic evaluations of imaging after acute stroke and identifies areas for improvement.

METHODS

We performed full-text searches of electronic databases that included Medline, Econlit, the National Health Service Economic Evaluation Database, and the Tufts Cost Effectiveness Analysis Registry through July 2012. Search strategy terms included the following: stroke*; cost*; or cost-benefit analysis*; and imag*. Inclusion criteria were empirical studies published in any language that reported the results of economic evaluations of imaging interventions for patients with stroke symptoms. Study quality was assessed by a commonly used checklist (with a score range of 0% to 100%).

RESULTS

Of 568 unique potential articles identified, 5 were included in the review. Four of 5 articles were explicit in their analysis perspectives, which included healthcare system payers, hospitals, and stroke services. Two studies reported results during a 5-year time horizon, and 3 studies reported lifetime results. All included the modified Rankin Scale score as an outcome measure. The median quality score was 84.4% (range=71.9%-93.5%). Most studies did not consider the possibility that patients could not tolerate contrast media or could incur contrast-induced nephropathy. Three studies compared perfusion computed tomography with unenhanced computed tomography but assumed that outcomes guided by the results of perfusion computed tomography were equivalent to outcomes guided by the results of magnetic resonance imaging or noncontrast computed tomography.

CONCLUSIONS

Economic evaluations of imaging modalities after acute ischemic stroke were generally of high methodological quality. However, important radiology-specific clinical components were missing from all of these analyses.

Machine learning for outcome prediction of acute ischemic stroke post intra-arterial therapy

Introduction

Stroke is a major cause of death and disability. Accurately predicting stroke outcome from a set of predictive variables may identify high-risk patients and guide treatment approaches, leading to decreased morbidity. Logistic regression models allow for the identification and validation of predictive variables. However, advanced machine learning algorithms offer an alternative, in particular, for large-scale multi-institutional data, with the advantage of easily incorporating newly available data to improve prediction performance. Our aim was to design and compare different machine learning methods, capable of predicting the outcome of endovascular intervention in acute anterior circulation ischaemic stroke.

Method

We conducted a retrospective study of a prospectively collected database of acute ischaemic stroke treated by endovascular intervention. Using SPSS®, MATLAB®, and Rapidminer®, classical statistics as well as artificial neural network and support vector algorithms were applied to design a supervised machine capable of classifying these predictors into potential good and poor outcomes. These algorithms were trained, validated and tested using randomly divided data.

Results

We included 107 consecutive acute anterior circulation ischaemic stroke patients treated by endovascular technique. Sixty-six were male and the mean age of 65.3. All the available demographic, procedural and clinical factors were included into the models. The final confusion matrix of the neural network, demonstrated an overall congruency of ∼80% between the target and output classes, with favourable receiving operative characteristics. However, after optimisation, the support vector machine had a relatively better performance, with a root mean squared error of 2.064 (SD: ±0.408).

Discussion

We showed promising accuracy of outcome prediction, using supervised machine learning algorithms, with potential for incorporation of larger multicenter datasets, likely further improving prediction. Finally, we propose that a robust machine learning system can potentially optimise the selection process for endovascular versus medical treatment in the management of acute stroke.

Recanalisation success is independent of ASPECTS in predicting outcomes after intra-arterial therapy for acute ischaemic stroke

Intra-arterial (IA) therapy for stroke is an increasingly utilised management approach for acute ischaemic stroke. We aimed to correlate radiological characteristics and recanalisation success with radiological and functional outcomes at 90 days in patients treated with IA therapy. This was a single centre, retrospective study investigating the correlation between pre-procedural Computed Tomography-Angiogram Source Image (CTA-SI) Alberta Stroke Program Early Computed Tomography Score (ASPECTS), recanalisation success, and functional outcome at 90 days in patients with an acute ischaemic stroke from 2007-2012. Outcome measures were pre-procedural non-contrast computed tomography (NCCT), CTA-SI, and post-procedural NCCT ASPECTS that were obtained and analysed by three blinded reviewers, recanalisation success (Thrombolysis in Cerebral Infarction [TICI] 2b-3) and favourable clinical outcome (90 day modified Rankin scale [mRS] score ≤ 2). Forty-four patients satisfied the inclusion criteria. The mean age was 64.2 years (standard deviation: 14.9; median: 66.5; interquartile range [IQR]: 54.5-76.5). The median National Institutes of Health Stroke Scale score was 17 (IQR: 13.5-20). Twenty-one (47.7%) patients achieved a mRS score ≤ 2. The 90 day mortality rate was 25.0% (n=11). Of the patients who achieved TICI ≥ 2b-3, 65.5% (19/29) achieved mRS 2. There was a statistically significant association between recanalisation success (TICI 2b) and favourable neurological outcome at 90 days (odds ratio [OR] 25.22, 95% confidence interval [CI]: 2.86-222.37, p<0.005). Patients with high pre-procedural CTA-SI ASPECTS are significantly more likely to have high post-procedural NCCT score (OR 23.36, 95% CI: 3.26-166.92, p=0.002). Recanalisation success was strongly associated with good clinical outcome, unaffected by known predictive factors, which included age and stroke severity. This association was unattenuated by CTA-SI ASPECTS.

The Role of Endovascular Therapy in the Treatment of Acute Ischemic Stroke

Of the approximately 795 000 strokes in the United States annually, 87% are ischemic and result in significant morbidity and mortality. Improvements in acute ischemic stroke (AIS) outcomes have been achieved with intravenous thrombolytics (IVT) and intra-arterial thrombolytics vs supportive medical therapy. Given its ease of administration, noninvasiveness, and most validated efficacy, IVT is the standard of care in AIS patients without contraindications to systemic fibrinolysis. However, patients with large-vessel occlusions respond poorly to IVT. Recent trials designed to select this population for randomization to IVT vs IVT with adjunctive endovascular therapy have not shown improvement in clinical outcomes with endovascular therapy. This could be due to the lack of utilization of modern thrombectomy devices such as Penumbra aspiration devices, Solitaire stent-trievers, or Trevo stent-trievers, which have shown the best recanalization results. Continued improvement in the techniques with using these devices as well as randomized controlled trials using them is warranted. This article defines the goals of AIS revascularization, presents the evolution of treatment from the initial use of IVT to modern thrombectomy devices, and discusses current treatment and ongoing AIS trials.

Safety and effectiveness of endovascular treatment of stroke with unknown time of onset

BACKGROUND

Currently, treatment options for patients with strokes with unknown time of onset (UKO) remain limited. With the advance of neuroimaging and endovascular treatment (EVT), selected patients might have a chance of a therapeutic option. We sought to compare clinical outcome after EVT in patients with known time of stroke onset (KO) and in those with UKO.

METHODS

We prospectively registered consecutive patients with acute large artery occlusion of the anterior territory who underwent EVT. Multimodal MR or Alberta Stroke Program early CT score (ASPECTS) and transcranial color-coded Duplex sonography were used to select patients for EVT. Recanalization, periprocedural complications, intracranial hemorrhage (ICH) and outcome were recorded. Symptomatic ICH (sICH) was defined as a worsening of ≥4 points in the National Institutes of Health Stroke Scale (NIHSS) score within 36 h in any bleeding. Favorable outcome was defined as a modified Rankin score ≤2 at 3 months.

RESULTS

A total of 141 patients were studied, 109 with KO and 32 with UKO. Mean age was 66.5 versus 64.7 years (p = 0.005) and median baseline NIHSS was 18 versus 17 (p = 0.095), respectively. Prior IV tPA was more frequently administered to KO patients (62.4 vs. 9.4%, p < 0.001), whereas patient selection using multimodal MR was more frequent in patients with UKO (78.1 vs. 45.4%, p < 0.001). Median time from stroke onset or from the last time the patient was seen well to groin puncture and to recanalization was significantly longer in patients with UKO, but no differences were found in the duration of the procedure. For KO/UKO patients recanalization was seen in 77.1 vs. 65.7% (p = 0.084), sICH occurred in 10 versus 0% (p = 0.061) and favorable outcome at 3 months was achieved in 41.3 versus 50% (p = 0.382), respectively.

CONCLUSIONS

Clinical outcomes in this series of EVT in ischemic stroke patients due to large anterior arterial occlusion with salvageable brain are similar for patients treated with KO and UKO. These data support a randomized study of EVT in extended or uncertain time windows..

Hospital-based financial analysis of endovascular therapy and intravenous thrombolysis for large vessel acute ischemic strokes: the 'bottom line'

BACKGROUND

Economic viability is important to any hospital striving to be a comprehensive stroke center. An inability to recover cost can strain sustained delivery of advanced stroke care.

OBJECTIVE

To carry out a comparative financial analysis of intravenous (IV) recombinant tissue plasminogen activator and endovascular (EV) therapy in treating large vessel strokes from a hospital's perspective.

METHODOLOGY

Actual hospital's charges, costs, and payments were analyzed for 265 patients who received treatment for large vessel strokes. The patients were divided into an EV (n=141) and an IV group (n=124). The net gain/loss was calculated as the difference between payments received and the total cost.

RESULTS

The charges, costs, and payments were significantly higher for the EV than the IV group (p<0.0001 for all). Medicare A was the main payer. Length of stay was inversely related to net gain/loss (p<0.0001). Favorable outcome was associated with a net gain of $3853 (±$21,155) and poor outcome with a net deficit of $2906 (±$15,088) (p=0.003). The hospital showed a net gain for the EV group versus a net deficit for the IV group in patients who survived the admission (p=0.04), had a favorable outcome (p=0.1), or were discharged to home (p=0.03). There was no difference in the time in hospital based on in-hospital mortality for the EV group but patients who died in the IV group had a significantly shorter length of stay than those who survived (p=0.04). The favorable outcome of 42.3% in the EV group was significantly higher than the 29.4% in the IV group (p=0.03).

CONCLUSIONS

Endovascular therapy was associated with better outcomes and higher cost-recovery than IV thrombolysis in patients with large vessel strokes.

Comparison of fast MRI-based individual thrombolysis therapy for patients with superacute infarction

BACKGROUND

The aim of this study is to investigate the outcomes of magnetic resonance imaging (MRI)-based individual thrombolysis therapy using recombinant tissue plasminogen activator (rt-PA) in patients with superacute infarction, comparing the outcome in 1 group of patients treated within 4.5 hours compared with 4.5- to 12-hour window treatment group.

METHODS

We studied 135 patients stratified to 2 different groups based on whether they presented with stroke symptoms within 4.5 hours (4.5-hour group, 72 patients) or between 4.5 and 12 hours (4.5- to 12-h group, 63 patients). All patients were treated with rt-PA after MRI confirmed superacute ischemic stroke (hyperintense in diffusion-weighted imaging but no hypointense change in T2-weighted image (T2WI) or fluid-attenuated inversion recovery). Clinical neurologic deficit was evaluated using the National Institutes of Health Stroke Scale on admission, at 24 hours, and 7 days later. A 90-day clinical outcome was assessed using the modified Rankin Scale (mRS).

RESULTS

There was no significant difference in the clinical outcome between the patients treated with thrombolysis within the first 4.5 hours and those treated between 4.5 and 12 hours. The 2 groups both had recanalization, mRS, and favorable outcome at 90 days (P > .05).

CONCLUSIONS

Our study suggested that fast MR-based thrombolysis using rt-PA was safe and reliable in superacute infarction within 4.5 hours and 4.5-12 hours poststroke.

Correlation of clot imaging with endovascular recanalization in internal carotid artery terminus occlusion

BACKGROUND AND PURPOSE

In a swine stroke model we have previously demonstrated a high-intensity fluid attenuated inversion recovery (FLAIR) signal representing the erythrocyte component of the clot. We hypothesized that the intensity of the FLAIR clot signal in patients with acute stroke may predict the efficacy of recanalization by thrombectomy devices. In this study we compared the pretreatment FLAIR signal intensity of the clots in the distal internal carotid artery (ICA) and the degree of angiographic recanalization rate after mechanical thrombectomy.

METHODS

25 consecutive acute stroke patients with ICA terminus (ICA-T) occlusion diagnosed with MRI at the UCLA Medical Center between 2002 and 2013 were retrospectively reviewed. The intensity of the FLAIR clot signal at the distal ICA was blindly compared with the angiographic recanalization status (successful recanalization defined as Thrombolysis In Cerebral Infarction (TICI) score of 2b-3) and non-successful recanalization as TICI score 0-2a) after endovascular treatment. Multivariate logistic regression analysis for successful recanalization was performed.

RESULTS

Successful recanalization was achieved in 40% of patients (10/25) and showed a significantly higher FLAIR intensity (p=0.014). The cut-off value for clot intensity on the FLAIR sequence to predict recanalization was 0.7952, with 70% sensitivity and 80% specificity (95% CI 0.59 to 0.96) using a receiver operating characteristic curve. In multivariate logistic regression analysis, only a high FLAIR clot intensity (>0.7952) was associated with successful recanalization (OR 16.79; 95% CI 1.29 to 218.92; p=0.031).

CONCLUSIONS

High signal intensity on FLAIR clot imaging may predict successful recanalization after endovascular therapy for ICA-T occlusion.

Imaging Oxygen Metabolism In Acute Stroke Using MRI

The ability to image the ischemic penumbra during hyper-acute stroke promises to identify patients who may benefit from treatment intervention beyond population-defined therapeutic time windows. MR blood oxygenation level dependent (BOLD) contrast imaging has been explored in ischemic stroke. This review provides an overview of several BOLD-based methods, including susceptibility weighted imaging (SWI), R2, R2*, R2', R2* under oxygen challenge, MR_OEF and MROMI approaches to assess cerebral oxygen metabolism in ischemic stroke. We will review the underlying pathophysiological basis of the imaging approaches, followed by a brief introduction of BOLD contrast. Finally, we will discuss the applications of the BOLD approaches in patients with ischemic stroke. BOLD-based methods hold promise for imaging tissue oxygenation during acute ischemia. Further technical refinement and validation studies in stroke patients against positron emission tomography (PET) measurements are needed.

Methodology of the Field Administration of Stroke Therapy - Magnesium (FAST-MAG) phase 3 trial: Part 1 - rationale and general methods

RATIONALE

Prehospital initiation by paramedics may enable delivery of neuroprotective therapies to stroke patients in the hyperacute period when they are most effective in preclinical studies. Magnesium is neuroprotective in experimental stroke models and has been shown to be safe with signals of potential efficacy when started early after onset of human cerebral ischemia.

AIMS

(a) To demonstrate that paramedic initiation of the neuroprotective agent magnesium sulfate in the field is an efficacious and safe treatment for acute stroke; (b) To demonstrate that field enrollment of acute stroke patients is a practical and feasible strategy for phase 3 stroke trials, permitting enrollment of greater numbers of patients in hyperacute time windows.

DESIGN

Multicenter, randomized, double-blinded, placebo-controlled, pivotal clinical trial.

STUDY PROCEDURES

The study is enrolling 1700 patients (850 in each arm) with likely acute stroke, including both cerebral infarction and intracerebral hemorrhage patients. Inclusion criteria are: (a) likely stroke as identified by the modified Los Angeles Prehospital Stroke Screen (mLAPSS), (b) age 40-95, (c) symptom onset within 2 h of treatment initiation, and (d) deficit present ≥15 min. Paramedics administer a loading dose of magnesium sulfate (Mg) or matched placebo in the field, 4 grams over 15 min. In the Emergency Department, a maintenance infusion follows, 16 grams Mg or matched placebo over 24 h.

OUTCOMES

The primary endpoint is the modified Rankin Scale measure of global disability, assessed using the Rankin Focused Assessment, 90 days after treatment. Secondary efficacy endpoints include the NIHSS (neurologic deficit), Barthel Index (activities of daily living), and the Stroke Impact Scale (quality of life).

Intra-arterial treatment of acute ischemic stroke: the continued evolution

OPINION STATEMENT

The devastation caused by acute ischemic strokes is evident in every intensive care unit across the world. Although there is no doubt that progress has been made in treatment, it has been slow to come. With the emergence of new technologies in imaging, thrombolysis and endovascular intervention, the treatment modalities of acute ischemic stroke will enter a new era. In this review, we present the concept of the seven evolutionary phases in the treatment of acute ischemic stroke to date.