Recanalization and clinical outcome of occlusion sites at baseline CT angiography in the Interventional Management of Stroke III trial

Endovascular therapy for acute ischemic stroke: The standard of care

Acute ischemic stroke continues to be a major cause of permanent disability and death worldwide. Outcomes are particularly poor in patients presenting with large vessel occlusive disease with resultant ischemia and tissue injury in large and eloquent territories. Intravenous thrombolysis has been the mainstay of medical therapy, however treatment is limited to a subset of patients and many patients continue to have poor outcomes. Three trials in 2013 investigating the benefit of intra-arterial therapy failed to demonstrate benefit over medical therapy alone. More recently, five trials in 2015 were completed demonstrating superior outcomes with intra-arterial therapy with improved results attributed to higher and faster rates of recanalization in a select patient population. These trials have introduced a new standard of care in the management of acute ischemic stroke patients.

Power of an Adaptive Trial Design for Endovascular Stroke Studies: Simulations Using IMS (Interventional Management of Stroke) III Data

BACKGROUND AND PURPOSE

Adaptive trial designs that allow enrichment of the study population through subgroup selection can increase the chance of a positive trial when there is a differential treatment effect among patient subgroups. The goal of this study is to illustrate the potential benefit of adaptive subgroup selection in endovascular stroke studies.

METHODS

We simulated the performance of a trial design with adaptive subgroup selection and compared it with that of a traditional design. Outcome data were based on 90-day modified Rankin Scale scores, observed in IMS III (Interventional Management of Stroke III), among patients with a vessel occlusion on baseline computed tomographic angiography (n=382). Patients were categorized based on 2 methods: (1) according to location of the arterial occlusive lesion and onset-to-randomization time and (2) according to onset-to-randomization time alone. The power to demonstrate a treatment benefit was based on 10 000 trial simulations for each design.

RESULTS

The treatment effect was relatively homogeneous across categories when patients were categorized based on arterial occlusive lesion and time. Consequently, the adaptive design had similar power (47%) compared with the fixed trial design (45%). There was a differential treatment effect when patients were categorized based on time alone, resulting in greater power with the adaptive design (82%) than with the fixed design (57%).

CONCLUSIONS

These simulations, based on real-world patient data, indicate that adaptive subgroup selection has merit in endovascular stroke trials as it substantially increases power when the treatment effect differs among subgroups in a predicted pattern.

Clot Burden Score on Baseline Computerized Tomographic Angiography and Intra-Arterial Treatment Effect in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

A high clot burden score (CBS) is associated with favorable outcome after intravenous treatment for acute ischemic stroke. The added benefit of intra-arterial treatment might be less in these patients. The aim of this exploratory post hoc analysis was to assess the relation of CBS with neurological improvement and endovascular treatment effect.

METHODS

For 499 of 500 patients in the MR CLEAN study (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands), the CBS was determined. Ordinal logistic regression models with and without main baseline prognostic variables were used to assess the association between CBS (continuous or dichotomized at CBS of 6) and a shift toward better outcome on the modified Rankin Scale. The model without main baseline prognostic variables only included treatment allocation and CBS. Models with and without a multiplicative interaction term of CBS and treatment were compared using the χ² test to assess treatment effect modification by CBS.

RESULTS

Higher CBS was associated with a shift toward better outcome on the modified Rankin Scale; adjusted common odds ratio per point CBS was 1.12 (95% confidence interval, 1.04-1.20]. Dichotomized CBS had an adjusted common odds ratio of 1.67 (95% confidence interval, 1.12-2.51). Both effect estimates were slightly attenuated by adding baseline prognostic variables. The addition of the interaction terms did not significantly improve the fit of the models. There was a small and insignificant increase of intra-arterial treatment efficacy in the high CBS group.

CONCLUSIONS

A higher CBS is associated with improved outcome and may be used as a prognostic marker. We found no evidence that CBS modifies the effect of intra-arterial treatment.

CLINICAL TRIAL REGISTRATION

URL: http://www.trialregister.nl. Unique identifier: NTR1804. URL: http://www.controlled-trials.com. Unique identifier: ISRCTN10888758.

Endovascular Therapy of M2 Occlusion in IMS III: Role of M2 Segment Definition and Location on Clinical and Revascularization Outcomes

BACKGROUND AND PURPOSE

Uncertainty persists regarding the safety and efficacy of endovascular therapy of M2 occlusions following IV tPA. We reviewed the impact of revascularization on clinical outcomes in 83 patients with M2 occlusions in the Interventional Management of Stroke III trial according to specific M1-M2 segment anatomic features.

MATERIALS AND METHODS

Perfusion of any M2 branch distinguished M2-versus-M1 occlusion. Prespecified modified TICI and arterial occlusive lesion revascularization and clinical mRS 0-2 end points at 90 days for endovascular therapy-treated M2 occlusions were analyzed. Post hoc analyses of the relationship of outcomes to multiple baseline angiographic M2 and M1 subgroup characteristics were performed.

RESULTS

Of 83 participants with M2 occlusion who underwent endovascular therapy, 41.0% achieved mRS 0-2 at 90 days, including 46.6% with modified TICI 2-3 reperfusion compared with 26.1% with modified TICI 0-1 reperfusion (risk difference, 20.6%; 95% CI, -1.4%-42.5%). mRS 0-2 outcome was associated with reperfusion for M2 trunk (n = 9) or M2 division (n = 42) occlusions, but not for M2 branch occlusions (n = 28). Of participants with trunk and division occlusions, 63.2% with modified TICI 2a and 42.9% with modified TICI 2b reperfusion achieved mRS 0-2 outcomes; mRS 0-2 outcomes for M2 trunk occlusions (33%) did not differ from distal (38.2%) and proximal (26.9%) M1 occlusions.

CONCLUSIONS

mRS 0-2 at 90 days was dependent on reperfusion for M2 trunk but not for M2 branch occlusions. For M2 division occlusions, good outcome with modified TICI 2b reperfusion did not differ from that in modified TICI 2a. M2 segment definition and occlusion location may contribute to differences in revascularization and good outcome between Interventional Management of Stroke III and other endovascular therapy studies.

History, Evolution, and Importance of Emergency Endovascular Treatment of Acute Ischemic Stroke

More than 800,000 people in North America suffer a stroke each year, with ischemic stroke making up the majority of these cases. The outcomes of ischemic stroke range from complete functional and cognitive recovery to severe disability and death; outcome is strongly associated with timely reperfusion treatment. Historically, ischemic stroke has been treated with intravenous thrombolytic agents with moderate success. However, five recently published positive trials have established the efficacy of endovascular treatment in acute ischemic stroke. In this review, we will discuss the history of stroke treatments moving from various intravenous thrombolytic drugs to intra-arterial thrombolysis, early mechanical thrombectomy devices, and finally modern endovascular devices. Early endovascular therapy failures, recent successes, and implications for current ischemic stroke management and future research directions are discussed.

R2* Map by IDEAL IQ for Acute Cerebral Infarction: Compared with Susceptibility Vessel Sign on T2*-Weighted Imaging

BACKGROUND

To evaluate the detectability of arterial acute thrombus on R2* map by iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) IQ compared with T2*-weighted imaging (T2*WI).

METHODS

Twenty-six patients with acute cerebral infarction who underwent R2* map and T2*WI were reviewed. We performed visual assessment of each sequence regarding the visibility of susceptibility effect reflecting acute thrombus and quantitative evaluation of the thrombus on R2* map.

RESULTS

Both R2* map and T2*WI showed susceptibility effect reflecting acute thrombi at the occluded site of magnetic resonance angiography (MRA) in 9 patients. R2* map revealed positive while T2*WI showed equivocal findings in 3 patients due to the surrounding vessel signal intensity. Acute thrombus at distal internal carotid artery (ICA) on R2* map was more clearly detected than that on T2*WI without any apparent susceptibility artifact from the skull base in 4 patients. Most of cardiogenic embolic infarction (CEI) and artery-to-artery embolic infarction (A-to-A) demonstrated positive and most of atherothrombotic infarction (ATI) revealed negative findings on R2* map, although quantitative R2* values of thrombi did not show significant differences between CEI (136.6 /msec) and A-to-A (189.9 /msec) (P = 0.332).

CONCLUSION

The detectability of acute thrombus on R2* map is comparable to that on T2*WI. Regarding thrombus at distal ICA, its detectability on R2* map is superior to that on T2*WI. R2* map provide additional information to distinguish between embolic and atherothrombotic infarctions.

Neuroimaging as a Selection Tool and Endpoint in Clinical and Pre-clinical Trials

Standard imaging in acute stroke enables the exclusion of non-stroke structural CNS lesions and cerebral haemorrhage from clinical and pre-clinical ischaemic stroke trials. In this review, the potential benefit of imaging (e.g., angiography and penumbral imaging) as a translational tool for trial recruitment and the use of imaging endpoints are discussed for both clinical and pre-clinical stroke research. The addition of advanced imaging to identify a “responder” population leads to reduced sample size for any given effect size in phase 2 trials and is a potentially cost-efficient means of testing interventions. In pre-clinical studies, technical failures (failed or incomplete vessel occlusion, cerebral haemorrhage) can be excluded early and continuous multimodal imaging of the animal from stroke onset is feasible. Pre- and post-intervention repeat scans provide real time assessment of the intervention over the first 4–6 h. Negative aspects of advanced imaging in animal studies include increased time under general anaesthesia, and, as in clinical studies, a delay in starting the intervention. In clinical phase 3 trial designs, the negative aspects of advanced imaging in patient selection include higher exclusion rates, slower recruitment, overestimated effect size and longer acquisition times. Imaging may identify biological effects with smaller sample size and at earlier time points, compared to standard clinical assessments, and can be adjusted for baseline parameters. Mechanistic insights can be obtained. Pre-clinically, multimodal imaging can non-invasively generate data on a range of parameters, allowing the animal to be recovered for subsequent behavioural testing and/or the brain taken for further molecular or histological analysis.

The Role of Vascular Imaging in the Initial Assessment of Patients with Acute Ischemic Stroke

Over the last few years, improvement in radiological imaging and treatment has changed the management of acute ischemic stroke. We have made significant advances in not only the imaging modalities themselves but also in identifying imaging parameters that can help us predict patient outcomes with both intravascular thrombolysis and endovascular thrombectomy. In this review, we describe the added utility of baseline vascular imaging including computed tomography angiography and magnetic resonance angiography in the diagnosis and management of patients with acute ischemic stroke. We focus on information these imaging modalities provide on clot characteristics, tissue state, collateral status, and endovascular planning. We also highlight the benefits of newer imaging modalities like dynamic computed tomography angiography (CTA) and multi-phase CTA. Lastly, we also describe some of the disadvantages of vascular imaging in ischemic stroke.

No space left for intravenous thrombolysis in acute stroke: CONS

Recent successful clinical trials of endovascular thrombectomy for large artery ischaemic stroke have established the value of this treatment modality as an adjunct to intravenous thrombolysis, not as an alternative: thrombectomy delivery was undertaken in the context of highly efficient networks for acute thrombolysis delivery and the great majority of patients received IV thrombolytic drug treatment. Even for the minority of acute stroke patients for whom thrombectomy is potentially relevant, access will be limited by geography and service infrastructure. Developments in intravenous thrombolysis in the near future will likely produce safer and more effective intravenous treatments. Intravenous thrombolysis will remain the first line of treatment for the great majority of acute stroke patients.

Endovascular thrombectomy for M2 occlusions: comparison between forced arterial suction thrombectomy and stent retriever thrombectomy

Background

To date there has been no direct comparison of two frequently used endovascular thrombectomy (EVT) methods (forced arterial suction thrombectomy (FAST) and stent retriever thrombectomy) in M2 occlusions. We review our experiences with EVT performed using FAST and stent retriever thrombectomy in such cases.

Methods

The subjects comprised 41 patients with an M2 occlusion who underwent EVT (25 with FAST, 16 with stent retriever thrombectomy). The patients' data were retrospectively analyzed to evaluate the technical characteristics and angiographic outcome of the two EVT techniques.

Results

Thrombolysis In Cerebral Infarction (TICI) grades 2b–3 using the first chosen technique did not differ significantly between the two techniques (FAST 64.0% vs stent retriever thrombectomy 81.2%, p=0.305). Time from groin puncture to reperfusion was significantly shorter for stent retriever thrombectomy (53.0 vs 38.5 min; p=0.045). Distal embolization occurred in three cases (12.0%) in the FAST group and in four (26.7%) in the stent retriever group (p=0.362). However, the two techniques did not differ significantly in the final TICI 2b–3 rate (72.0% vs 87.5%; p=0.441). A frequent angiographic finding regarding the failure of FAST was that the M2 occlusion was located immediately after severe acute angulation between M1 and M2.

Conclusions

Stent retriever thrombectomy may provide faster reperfusion than FAST, while the FAST technique might be associated with lower distal embolization and a higher reperfusion rate for the first thrombectomy attempt, but without any significant difference in clinical outcome. When choosing the EVT method for M2 occlusions, consideration of the location of the occlusion and tortuosity between M1 and M2 might be helpful to achieve a better angiographic outcome.

Recanalization and Angiographic Reperfusion Are Both Associated with a Favorable Clinical Outcome in the IMS III Trial

BACKGROUND

Prompt revascularization is the main goal of acute ischemic stroke treatment. We examined which revascularization scale - reperfusion (modified Treatment in Cerebral Infarctions, mTICI) or recanalization (Arterial Occlusive Lesion, AOL) - better predicted the clinical outcome in ischemic stroke participants treated with endovascular therapy (EVT). Additionally, we determined the optimal thresholds for the predictive accuracy of each scale.

METHODS

We included participants from the Interventional Management of Stroke (IMS) III trial with complete occlusion in the internal carotid artery terminus or proximal middle cerebral artery (M1 or M2) who completed EVT within 7 h of symptom onset. The abilities of the AOL and mTICI scales to predict a favorable outcome (defined as a modified Rankin Scale score of 0-2 at 3 months) were compared by receiver operating characteristic analyses. The maximal sensitivity and specificity for each revascularization scale were established.

RESULTS

Among 240 participants who met the study inclusion criteria, 79 (33%) achieved a favorable outcome. Higher scores of mTICI and AOL increased the likelihood of a favorable outcome (2.7% with mTICI 0 vs. 83.3% with mTICI 3, and 3.0% with AOL 0 vs. 43% with AOL 3). The accuracy of mTICI reperfusion and AOL recanalization for a favorable outcome prediction was similar, with optimal thresholds of mTICI 2b/3 and AOL 3, respectively.

CONCLUSION

Reperfusion (mTICI) and recanalization (AOL) predicted a favorable clinical outcome with comparable accuracy in ischemic stroke participants treated with EVT. Optimal revascularization goals to maximize clinical outcome (modified Rankin Scale score of 0-2) consisted of complete recanalization (AOL 3) and reperfusion of at least 50% of the arterial tree of the symptomatic artery (mTICI 2b/3) in the IMS III trial setting.

Interaction of Recanalization, Intracerebral Hemorrhage, and Cerebral Edema After Intravenous Thrombolysis

BACKGROUND AND PURPOSE

Both intracerebral hemorrhage (ICH) and brain edema have been attributed to reperfusion after intravenous thrombolysis. We explored the interaction of recanalization and core size for imaging outcomes (ICH and vasogenic brain edema).

METHODS

In patients with anterior circulation occlusion given intravenous thrombolysis <4.5 hours and imaged with computed tomographic (CT) perfusion and CT angiography, we defined volumes of core (relative delay time >2 s and relative cerebral blood flow <40%) and penumbra (relative delay time >2 s). CT and CT angiography at 24 hours were reviewed for ICH (European Cooperative Acute Stroke Study [ECASS]-2 definition), early vasogenic edema (third International Stroke Trial [IST-3] criteria), and recanalization (thrombolysis in myocardial infarction 2-3). Independent effects of recanalization, core volume and potential interactions on edema, ICH and day 90 outcomes were estimated by logistic regression.

RESULTS

In 123 patients, there was a trend for recanalization to be associated with H1/2 ICH (odds ratio [OR], 2.3 [0.97-5.5]; P=0.06) but not with PH1/2 ICH (OR, 1.7 [0.33-8.8]; P=0.5), any edema, or significant brain edema (OR, 1.45 [0.4-4.9]; P=0.55). Ischemic core (>50 mL) was associated with any ICH (OR, 4.0 [1.6-9.5]; P=0.003), edema (OR, 5.4 [2-14]; P<0.01), and significant brain edema (OR, 17.4 [5.3-57]; P<0.01) but not with PH1/2 ICH (OR, 1.2 [0.23-6.5]; P=0.8), after controlling for recanalization. There was no significant interaction of recanalization and large core for any adverse outcomes.

CONCLUSIONS

Large ischemic core was associated with poorer outcomes and both early vasogenic brain edema and ICH, but recanalization on 24-hour CT angiography was associated with clinically favorable outcome. There was no significant interaction of recanalization and large core volume for any outcomes. The association of hemorrhage or brain edema with post-thrombolysis reperfusion is unclear.

Endovascular Treatment versus Best Medical Treatment in Patients with Acute Ischemic Stroke: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND PURPOSE

Endovascular treatment has emerged as a minimally invasive technique for patients with acute ischemic stroke to achieve recanalization. Our aim was to determine the effects of endovascular treatment on clinical and safety outcomes compared with best medical treatment.

MATERIALS AND METHODS

Fifteen randomized trials that compared endovascular treatment with best medical treatment in patients with acute ischemic stroke met the inclusion criteria. We calculated pooled odds ratios and 95% CIs by using random-effects models. The primary end point was a favorable outcome defined by a modified Rankin Scale score of 0 (no symptoms), 1 (no significant disability), or 2 (slight disability) at 90 days postrandomization.

RESULTS

Of the 2980 subjects randomized, the proportion of subjects who achieved a favorable outcome was significantly greater among those randomized to endovascular treatment compared with best medical treatment (2949 subjects analyzed; odds ratio, 1.82; 95% CI, 1.38-2.40; P < .001). Excellent outcome (modified Rankin Scale score of 0 or 1) was also significantly greater among those randomized to endovascular treatment (2791 subjects analyzed; odds ratio, 1.77; 95% CI, 1.29-2.43, P < .001). Risk of symptomatic intracranial hemorrhage was similar between endovascular treatment and best medical treatment (2906 subjects analyzed; odds ratio, 1.19; 95% CI, 0.84-1.68; P = .34).

CONCLUSIONS

Compared with best medical treatment, the odds of achieving a favorable outcome or excellent outcome at 3 months postrandomization are approximately 80% higher with endovascular treatment among patients with acute ischemic stroke.

Mechanical thrombectomy for anterior circulation stroke: 5-year experience in a statewide service with differences in pretreatment time metrics across two hospitals sites

OBJECTIVE

To audit our institutional mechanical thrombectomy (MT) outcomes for acute anterior circulation stroke and examine the influence of workflow time metrics on patient outcomes.

METHODS

A database of 100 MT cases was maintained throughout May 2010-February 2015 as part of a statewide service provided across two tertiary hospitals (H1 and H2). Patient demographics, stroke and procedural details, blinded angiographic outcomes, and 90-day modified Rankin Scale (mRS) scores were recorded. The following time points in stroke treatment were recorded: stroke onset, hospital presentation, CT imaging, arteriotomy, and recanalization. Statistical analysis of outcomes, predictors of outcome, and differences between the hospitals was carried out.

RESULTS

Thrombolysis in Cerebral Infarction (TICI) 2b/3 reperfusion was 79%. Forty-nine per cent of patients had good clinical outcomes (mRS 0-2). In a subgroup analysis of 76 patients with premorbid mRS 0-1 and first CT performed ≤4.5 h after stroke onset, 60% had good clinical outcomes. Patient and disease characteristics were matched between the two hospitals. H1 had shorter times between hospital presentation and CT (32 vs 55 min, p=0.01), CT and arteriotomy (33 vs 69 min, p=0.00), and stroke onset and recanalization (198 vs 260 min, p=0.00). These time metrics independently predicted good clinical outcome. Median days spent at home in the first 90 days was greater at H1 (61 vs 8, p=0.04) than at H2. A greater proportion of patients treated at H1 were independent (mRS 0-2) at 90 days (54% vs 42%); however, this was not statistically significant (p=0.22).

CONCLUSIONS

Outcomes similar to randomized controlled trials are attainable in 'real-world' settings. Workflow time metrics were independent predictors of clinical outcome, and differed between the two hospitals owing to site-specific organizational differences.

Evolving Treatments for Acute Ischemic Stroke

The purpose of this article is to review advances in stroke treatment in the hyperacute period. With recent evolutions of technology in the fields of imaging, thrombectomy devices, and emergency room workflow management, as well as improvement in statistical methods and study design, there have been ground breaking changes in the treatment of acute ischemic stroke. We describe how stroke presents as a clinical syndrome and how imaging as the most important biomarker will help differentiate between stroke subtypes and treatment eligibility. The evolution of hyperacute treatment has led to the current standard of care: intravenous thrombolysis with tissue-type plasminogen activator and endovascular treatment for proximal vessel occlusion in the anterior cerebral circulation. All patients with acute ischemic stroke are in need of hyperacute secondary prevention because the risk of recurrence is highest closest to the index event. The dominant themes of modern stroke care are the use of neurovascular imaging and speed of diagnosis and treatment.

Multimodal CT Imaging: Time to Treatment and Outcomes in the IMS III Trial

BACKGROUND AND PURPOSE

The importance of time in acute stroke is well-established. Using the Interventional Management of Stroke III trial data, we explored the effect of multimodal imaging (CT perfusion and/or CT angiography) versus noncontrast CT alone on time to treatment and outcomes.

MATERIALS AND METHODS

We examined 3 groups: 1) subjects with baseline CTP and CTA (CTP+CTA), 2) subjects with baseline CTA without CTP (CTA), and 3) subjects with noncontrast head CT alone. The demographics, treatment time intervals, and clinical outcomes in these groups were studied.

RESULTS

Of 656 subjects enrolled in the Interventional Management of Stroke III trial, 90 (13.7%) received CTP and CTA, 216 (32.9%) received CTA (without CTP), and 342 (52.1%) received NCCT alone. Median times for the CTP+CTA, CTA, and NCCT groups were as follows: stroke onset to IV tPA (120.5 versus 117.5 versus 120 minutes; P = .5762), IV tPA to groin puncture (77.5 versus 81 versus 91 minutes; P = .0043), groin puncture to endovascular therapy start (30 versus 38 versus 44 minutes; P = .0001), and endovascular therapy start to end (63 versus 46 versus 74 minutes; P < .0001). Compared with NCCT, the CTA group had better outcomes in the endovascular arm (OR, 2.12; 95% CI, 1.36-3.31; adjusted for age, NIHSS score, and time from onset to IV tPA). The CTP+CTA group did not have better outcomes compared with the NCCT group.

CONCLUSIONS

Use of CTA with or without CTP did not delay IV tPA or endovascular therapy compared with NCCT in the Interventional Management of Stroke III trial.

Selection of Patients and Anesthetic Types for Endovascular Treatment in Acute Ischemic Stroke: A Meta-Analysis of Randomized Controlled Trials

Background

and Purpose Recent randomized controlled trials have demonstrated consistent effectiveness of endovascular treatment (EVT) for acute ischemic stroke, leading to update on stroke management guidelines. We conducted this meta-analysis to assess the efficacy and safety of EVT overall and in subgroups stratified by age, baseline stroke severity, brain imaging feature, and anesthetic type.

Methods

Published randomized controlled trials comparing EVT and standard medical care alone were evaluated. The measured outcomes were 90-day functional independence (modified Rankin Scale ≤2), all-cause mortality, and symptomatic intracranial hemorrhage.

Results

Nine trials enrolling 2476 patients were included (1338 EVT, 1138 standard medical care alone). For patients with large vessel occlusions confirmed by noninvasive vessel imaging, EVT yielded improved functional outcome (pooled odds ratio [OR], 2.02; 95% confidence interval [CI], 1.64–2.50), lower mortality (OR, 0.75; 95% CI, 0.58–0.97), and similar symptomatic intracranial hemorrhage rate (OR, 1.12; 95% CI, 0.72–1.76) compared with standard medical care. A higher proportion of functional independence was seen in patients with terminus intracranial artery occlusion (±M1) (OR, 3.16; 95% CI, 1.64–6.06), baseline Alberta Stroke Program Early CT score of 8–10 (OR, 2.11; 95% CI, 1.25–3.57) and age ≤70 years (OR, 3.01; 95% CI, 1.73–5.24). EVT performed under conscious sedation had better functional outcomes (OR, 2.08; 95% CI, 1.47–2.96) without increased risk of symptomatic intracranial hemorrhage or short-term mortality compared with general anesthesia.

Conclusions

Vessel-imaging proven large vessel occlusion, a favorable scan, and younger age are useful predictors to identify anterior circulation stroke patients who may benefit from EVT. Conscious sedation is feasible and safe in EVT based on available data. However, firm conclusion on the choice of anesthetic types should be drawn from more appropriate randomized controlled trials.

Differentiating Carotid Terminus Occlusions into Two Distinct Populations Based on Willisian Collateral Status

Background and Purpose

The outcomes of acute internal carotid artery (ICA) terminus occlusions are poor. We classified ICA terminus occlusions into 2 groups according to the occlusion pattern of the circle of Willis and hypothesized that clinical outcomes would significantly differ between them.

Methods

Consecutive patients with acute ICA terminus occlusions evaluated by baseline computed tomographic angiography were enrolled. We investigated the occlusion patterns in the circle of Willis, retrospectively classified patients into simple ICA terminus occlusion (STO; with good Willisian collaterals from neighboring cerebral circulation) and complex ICA terminus occlusion (CTO; with one or more of A2 anterior cerebral artery, fetal posterior cerebral artery occlusion, or hypoplastic/absent contralateral A1; or with poor collaterals from anterior communicating artery) groups, and compared their baseline characteristics and outcomes.

Results

The STO group (n=58) showed smaller infarct volumes at 72 hours than the CTO group (n=34) (median, 81 mL [interquartile range, 38-192] vs. 414 mL [193-540], P<0.001) and more favorable outcomes (3-month modified Rankin Scale 0-3, 44.8% vs. 8.8%, P<0.001; 3-month mortality, 24.1% vs. 67.6%, P<0.001). In multivariable analyses, STO remained an independent predictor for favorable outcomes (odds ratio 6.1, P=0.010).

Conclusions

Favorable outcomes in STO group suggested that the outcomes of acute ICA terminus occlusions depend on Willisian collateral status. Documenting the subtypes on computed tomographic angiography would help predict patient outcome.

Meta-Analysis of Local Endovascular Therapy for Acute Ischemic Stroke

A meta-analysis was performed to assess randomized controlled trials comparing local endovascular therapy (with and without intravenous thrombolysis) versus standard care (intravenous thrombolysis alone when appropriate) for acute ischemic stroke. Local endovascular therapy showed a significant improvement in functional independence versus standard care (odds ratio, 1.779; 95% confidence interval, 1.262-2.507; P < .001). This benefit strengthened further on subgroup analyses of trials in which a majority of cases used stent retrievers, trials with intravenous thrombolysis use in both arms when appropriate, and trials that required preprocedural imaging of all patients. There were no significant differences between arms in terms of mortality, hemicraniectomy, intracranial hemorrhage, and cerebral edema rates (P > .05). In conclusion, in the treatment of acute ischemic stroke, local endovascular therapy leads to improved functional independence compared with standard care.

Update of the Korean Clinical Practice Guidelines for Endovascular Recanalization Therapy in Patients with Acute Ischemic Stroke

Patients with severe stroke due to acute large cerebral artery occlusion are likely to be severely disabled or dead without timely reperfusion. Previously, intravenous tissue plasminogen activator (IV-TPA) within 4.5 hours after stroke onset was the only proven therapy, but IV-TPA alone does not sufficiently improve the outcome of patients with acute large artery occlusion. With the introduction of the advanced endovascular therapy, which enables more fast and more successful recanalization, recent randomized trials consecutively and consistently demonstrated the benefit of endovascular recanalization therapy (ERT) when added to IV-TPA. Accordingly, to update the recommendations, we assembled members of the writing committee appointed by the Korean Stroke Society, the Korean Society of Interventional Neuroradiology, and the Society of Korean Endovascular Neurosurgeons. Reviewing the evidences that have been accumulated, the writing members revised recommendations, for which formal consensus was achieved by convening a panel composed of 34 experts from the participating academic societies. The current guideline provides the evidence-based recommendations for ERT in patients with acute large cerebral artery occlusion regarding patient selection, treatment modalities, neuroimaging evaluation, and system organization.

Imaging Paradigms in Acute Ischemic Stroke: A Pragmatic Evidence-based Approach

Online supplemental material is available for this article.

Cerebral collaterals and collateral therapeutics for acute ischemic stroke

Cerebral collaterals are vascular redundancies in the cerebral circulation that can partially maintain blood flow to ischemic tissue when primary conduits are blocked. After occlusion of a cerebral artery, anastomoses connecting the distal segments of the MCA with distal branches of the ACA and PCA (known as leptomeningeal or pial collaterals) allow for partially maintained blood flow in the ischemic penumbra and delay or prevent cell death. However, collateral circulation varies dramatically between individuals, and collateral extent is significant predictor of stroke severity and recanalization rate. Collateral therapeutics attempt to harness these vascular redundancies by enhancing blood flow through pial collaterals to reduce ischemia and brain damage after cerebral arterial occlusion. While therapies to enhance collateral flow remain relatively nascent neuroprotective strategies, experimental therapies including inhaled NO, transient suprarenal aortic occlusion, and electrical stimulation of the parasympathetic sphenopalatine ganglion show promise as collateral therapeutics with the potential to improve treatment of acute ischemic stroke.

Endovascular Therapy Is Effective and Safe for Patients With Severe Ischemic Stroke: Pooled Analysis of Interventional Management of Stroke III and Multicenter Randomized Clinical Trial of Endovascular Therapy for Acute Ischemic Stroke in the Netherlands Data

BACKGROUND AND PURPOSE

We assessed the effect of endovascular treatment in acute ischemic stroke patients with severe neurological deficit (National Institutes of Health Stroke Scale score, ≥20) after a prespecified analysis plan.

METHODS

The pooled analysis of the Interventional Management of Stroke III (IMS III) and Multicenter Randomized Clinical Trial of Endovascular Therapy for Acute Ischemic Stroke in the Netherlands (MR CLEAN) trials included participants with an National Institutes of Health Stroke Scale score of ≥20 before intravenous tissue-type plasminogen activator (tPA) treatment (IMS III) or randomization (MR CLEAN) who were treated with intravenous tPA ≤3 hours of stroke onset. Our hypothesis was that participants with severe stroke randomized to endovascular therapy after intravenous tPA would have improved 90-day outcome (distribution of modified Rankin Scale scores), when compared with those who received intravenous tPA alone.

RESULTS

Among 342 participants in the pooled analysis (194 from IMS III and 148 from MR CLEAN), an ordinal logistic regression model showed that the endovascular group had superior 90-day outcome compared with the intravenous tPA group (adjusted odds ratio, 1.78; 95% confidence interval, 1.20-2.66). In the logistic regression model of the dichotomous outcome (modified Rankin Scale score, 0-2, or functional independence), the endovascular group had superior outcomes (adjusted odds ratio, 1.97; 95% confidence interval, 1.09-3.56). Functional independence (modified Rankin Scale score, ≤2) at 90 days was 25% in the endovascular group when compared with 14% in the intravenous tPA group.

CONCLUSIONS

Endovascular therapy after intravenous tPA within 3 hours of symptom onset improves functional outcome at 90 days after severe ischemic stroke.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00359424 (IMS III) and ISRCTN10888758 (MR CLEAN).

Endovascular vs medical management of acute ischemic stroke

OBJECTIVE

To compare the outcomes between endovascular and medical management of acute ischemic stroke in recent randomized controlled trials (RCT).

METHODS

A systematic literature review was performed, and multicenter, prospective RCTs published from January 1, 2013, to May 1, 2015, directly comparing endovascular therapy to medical management for patients with acute ischemic stroke were included. Meta-analyses of modified Rankin Scale (mRS) and mortality at 90 days and symptomatic intracranial hemorrhage (sICH) for endovascular therapy and medical management were performed.

RESULTS

Eight multicenter, prospective RCTs (Interventional Management of Stroke [IMS] III, Local Versus Systemic Thrombolysis for Acute Ischemic Stroke [SYNTHESIS] Expansion, Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy [MR RESCUE], Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands [MR CLEAN], Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness [ESCAPE], Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial [EXTEND-IA], Solitaire With the Intention For Thrombectomy as Primary Endovascular Treatment [SWIFT PRIME], and Endovascular Revascularization With Solitaire Device Versus Best Medical Therapy in Anterior Circulation Stroke Within 8 Hours [REVASCAT]) comprising 2,423 patients were included. Meta-analysis of pooled data demonstrated functional independence (mRS 0-2) at 90 days in favor of endovascular therapy (odds ratio [OR] = 1.71; p = 0.005). Subgroup analysis of the 6 trials with large vessel occlusion (LVO) criteria also demonstrated functional independence at 90 days in favor of endovascular therapy (OR = 2.23; p < 0.00001). Subgroup analysis of the 5 trials that primarily utilized stent retriever devices (≥70%) in the intervention arm demonstrated functional independence at 90 days in favor of endovascular therapy (OR = 2.39; p < 0.00001). No difference was found for mortality at 90 days and sICH between endovascular therapy and medical management in all analyses and subgroup analyses.

CONCLUSIONS

This meta-analysis provides strong evidence that endovascular intervention combined with medical management, including IV tissue plasminogen activator for eligible patients, improves the outcomes of appropriately selected patients with acute ischemic stroke in the setting of LVO.

[Mechanical thrombectomy for acute ischemic stroke : current evidence and open questions]

OBJECTIVE

To determine the importance of mechanical thrombectomy (MT) in the treatment of ischemic stroke.

MATERIAL AND METHODS

Analysis and comparison of randomized controlled trials (RCT) of MT versus i.v. thrombolysis (IVT) considering pathophysiological and logistic aspects.

RESULTS

The use of MT is more effective than IVT for internal carotid artery terminus (ICAT), M1 segment and tandem occlusions, i.e. proximal internal carotid artery (ICA) occlusion or stenosis, even in patients older than 75-80 years of age. Due to the small sample sizes this question cannot be answered for patients with M2 occlusions. It is still uncertain whether MT is needed in patients with a low National Institutes of Health stroke scale (NIHSS) score, whether IVT is needed before MT and what type of imaging should be performed. Approximately one third of eligible patients currently undergo MT in Germany. Results from RCTs with stent retrievers for patients with vertebrobasilar artery occlusions are lacking.

CONCLUSION

After becoming established as a first-line therapy for patients with ICAT, M1 segment and tandem occlusions, the effectiveness of MT with stent retrievers has to proven in patients with more distal occlusions, low NIHSS scores and even vertebrobasilar artery occlusions.

Choosing a Hyperacute Stroke Imaging Protocol for Proper Patient Selection and Time Efficient Endovascular Treatment: Lessons from Recent Trials

Recently, several prospective randomized control trials regarding endovascular treatment for patients with intracranial large artery occlusions causing acute ischemic stroke have been successfully reported. Effort to minimize time delays to endovascular treatment, patient selection and the use of retrievable stent were important factors for the success of these trials. The inclusion and exclusion criteria for each of these trials did include differences in imaging protocols. In this review, we focus on the importance of baseline non-invasive angiography prior to deciding endovascular treatment. Then imaging protocols are described for each trial according to measurement of infarct volume and collateral grading.

Mechanical Thrombectomy Is Now the Gold Standard for Acute Ischemic Stroke: Implications for Routine Clinical Practice

BACKGROUND

This review aims to summarize the findings of the recently published randomized controlled studies which provide overwhelming evidence in support of mechanical thrombectomy for acute ischemic stroke with large artery occlusion. The five studies, Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), Endovascular Revascularization with Solitaire Device versus Best Medical Therapy in Anterior Circulation Stroke within 8 h (REVASCAT), Endovascular Treatment for Small Core and Proximal Occlusion Ischemic Stroke (ESCAPE), Solitaire™ FR as Primary Treatment for Acute Ischemic Stroke (SWIFT PRIME) and Extending the Time for Thrombolysis in Emergency Neurological Deficits with Intra-Arterial Therapy (EXTEND IA) have demonstrated the critical role of selecting patients by advanced neuroimaging, the superior recanalization capacity of stent retrievers and the effects of minimization of work processes delay.

SUMMARY

This review outlines lessons gained from the 5 positive studies which assessed mechanical thrombectomy as part of endovascular therapy for patients with proximal artery occlusion in the internal carotid and middle cerebral arteries. It discusses the role of age and stroke severity on treatment while also comparing the unique trial designs and selection criteria used amongst the 5 studies. In addition to examining the importance of unique imaging parameters such as collateral circulation, mismatch ratio and ischemic core volume, the review outlines differences in workflow parameters within the context of outcome. Finally the benefit of neuroimaging to broaden treatment eligibility and the issues associated with general anesthesia will be discussed in this review.

KEY MESSAGES

Questions remain over the applicability of mechanical thrombectomy to stroke subgroups including wake-up strokes and basilar artery thrombosis. The role of imaging is integral to this process and can lead to broadening eligibility criteria in the future. Workflow practices have been streamlined in the 5 positive randomized controlled studies, but guidelines will need to be revised accordingly if similar patient outcomes are to be replicated in a wider population.

Factors associated with recurrent stroke and recanalization in patients presenting with isolated symptomatic carotid occlusion

Background and purpose

Patients with symptomatic internal carotid artery (ICA) occlusion constitute a small proportion of stroke/transient ischaemic attack patients who are at increased risk of early stroke recurrence and poor outcome. The optimal medical treatment for patients with symptomatic ICA occlusion who are ineligible for thrombolysis or thrombectomy is unknown.

Methods

Consecutive patients presenting at a single center with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) were retrospectively reviewed. Those treated with intravenous thrombolysis or intra‐arterial thrombolysis/thrombectomy were excluded. Patients were divided into two groups based on whether they experienced recurrent in‐hospital stroke.

Results

The selected study population (n = 33) represented a small (20.4%) proportion of all newly symptomatic carotid occlusions, who nevertheless had an elevated risk of recurrent stroke during admission (24.2%). Of the variables examined (age, gender, admission National Institutes of Health Stroke Scale score, vascular risk factors, atrial fibrillation, prior stroke/transient ischaemic attack and anticoagulation within 48 h of presentation), only anticoagulation was significantly associated with a lower risk of in‐hospital recurrent stroke. Anticoagulated patients showed a decreased incidence of stroke recurrence within the first week (6.7% vs. 38.9%, P = 0.032) and fewer strokes or deaths at 1 month (13.3% vs. 47.1%, P = 0.040). Hemorrhagic transformation was not observed in any patient. On follow‐up imaging, ICA recanalization was significantly more frequent in anticoagulated patients (46.2% vs. 9.1%, P = 0.047).

Conclusion

Patients with newly diagnosed symptomatic ICA occlusion (not involving the circle of Willis) represent a small but high risk subgroup of patients with carotid occlusion. Early anticoagulation was associated with fewer recurrent strokes and increased ICA recanalization. Larger scale prospective studies may be justified.

Imaging-Based Patient Selection and Endovascular Therapy of Ischemic Stroke: A Stratified Meta-Analysis

The positive results of recent trials for the treatment of acute ischemic stroke have highlighted the importance of imaging selection before endovascular therapy. We performed a stratified meta-analysis to confirm this new understanding. We searched EMBASE, PubMed, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov in April 2015 for randomized controlled trials evaluating the effect of endovascular treatment in patients with acute ischemic stroke. The meta-analysis was stratified by whether computed tomographic angiography (CTA) was used to select patients. Outcome data were pooled using fixed-effects models. Seven randomized controlled trials with 2217 patients were included in this study. Endovascular therapy significantly increased the rate of 90-day functional independence (a modified Rankin score of 0-2) in patients with a CTA-confirmed large-vessel occlusion (relative risk [RR] = 1.75, 95% confidence interval [CI]: 1.48-2.06, I = 0.0%), and reduced 90-day mortality in patients with occlusion stroke with a small ischemic core (RR = 0.58, 95% CI: 0.37-0.89, I = 0.0%). The functional benefit was significantly greater in patients with CTA-based selection than in those without (Z = 5.04, P < 0.001). The mortality benefit was significantly greater in patients with a large-vessel occlusion and a small ischemic core than in those without CTA-based selection (Z = 2.04, P = 0.041). There was no evidence of between-study heterogeneity or publication bias. This meta-analysis showed the effect of vascular imaging on identifying patients with acute ischemic stroke with a proximal vessel occlusion and a small ischemic core, who would benefit from endovascular therapy.

Improved clinical outcome 3 months after endovascular treatment, including thrombectomy, in patients with acute ischemic stroke: a meta-analysis

Background and purpose

Intravenous thrombolysis with tissue plasminogen activator is standard treatment in acute stroke today. The benefit of endovascular treatment has been questioned. Recently, studies evaluating endovascular treatment and intravenous thrombolysis compared with intravenous thrombolysis alone, have reported improved outcome for the intervention group. The aim of this study was to perform a meta-analysis of randomized controlled trials comparing endovascular treatment in addition to intravenous thrombolysis with intravenous thrombolysis alone.

Methods

Databases were searched for eligible randomized controlled trials. The primary outcome was a functional neurological outcome after 90 days. A secondary outcome was severe disability and death. Data were pooled in the control and intervention groups, and OR was calculated on an intention to treat basis with 95% CIs. Outcome heterogeneity was evaluated with Cochrane's Q test (significance level cut-off value at <0.10) and I² (significance cut-off value >50%) with the Mantel–Haenszel method for dichotomous outcomes. A p value <0.05 was regarded as statistically significant.

Results

Six studies met the eligibility criteria, and data from 1569 patients were analyzed. A higher probability of a functional neurological outcome after 90 days was found for the intervention group (OR 2, 95% CI 2 to 3). There was a significantly higher probability of death and severe disability in the control group compared with the intervention group.

Conclusions

Endovascular treatment in addition to intravenous thrombolysis for acute ischemic stroke leads to an improved clinical outcome after 3 months, compared with patients receiving intravenous thrombolysis alone.

Endovascular stent thrombectomy: the new standard of care for large vessel ischaemic stroke

BACKGROUND

Results of initial randomised trials of endovascular treatment for ischaemic stroke, published in 2013, were neutral but limited by the selection criteria used, early-generation devices with modest efficacy, non-consecutive enrollment, and treatment delays.

RECENT DEVELOPMENTS

In the past year, six positive trials of endovascular thrombectomy for ischaemic stroke have provided level 1 evidence for improved patient outcome compared with standard care. In most patients, thrombectomy was performed in addition to thrombolysis with intravenous alteplase, but benefits were also reported in patients ineligible for alteplase treatment. Despite differences in the details of eligibility requirements, all these trials required proof of major vessel occlusion on non-invasive imaging and most used some imaging technique to exclude patients with a large area of irreversibly injured brain tissue. The results indicate that modern thrombectomy devices achieve faster and more complete reperfusion than do older devices, leading to improved clinical outcomes compared with intravenous alteplase alone. The number needed to treat to achieve one additional patient with independent functional outcome was in the range of 3·2-7·1 and, in most patients, was in addition to the substantial efficacy of intravenous alteplase. No major safety concerns were noted, with low rates of procedural complications and no increase in symptomatic intracerebral haemorrhage. WHERE NEXT?: Thrombectomy benefits patients across a range of ages and levels of clinical severity. A planned meta-analysis of individual patient data might clarify effects in under-represented subgroups, such as those with mild initial stroke severity or elderly patients. Imaging-based selection, used in some of the recent trials to exclude patients with large areas of irreversible brain injury, probably contributed to the proportion of patients with favourable outcomes. The challenge is how best to implement imaging in clinical practice to maximise benefit for the entire population and to avoid exclusion of patients with smaller yet clinically important potential to benefit. Although favourable imaging identifies patients who might benefit despite long delays from symptom onset to treatment, the proportion of patients with favourable imaging decreases with time. Health systems therefore need to be reorganised to deliver treatment as quickly as possible to maximise benefits. On the basis of available trial data, intravenous alteplase remains the initial treatment for all eligible patients within 4·5 h of stroke symptom onset. Those patients with major vessel occlusion should, in parallel, proceed to endovascular thrombectomy immediately rather than waiting for an assessment of response to alteplase, because minimising time to reperfusion is the ultimate aim of treatment.

Interventionalist Perspective on the New Endovascular Trials

Three recently published trials have conclusively proven the benefit of mechanical endovascular thrombectomy over best medical therapy for patients with acute ischemic stroke and large vessel occlusion. These trials shared some features and differed in others. These similarities and differences in trial design and execution affect the conclusions and recommendations that can be made from the data. We will examine the implications of these studies for neurointerventionists, both for current practice and for future studies. In particular, we will focus on procedural details such as patient selection, devices, adjunctive therapies, treatment time windows, and performance metrics.

Intra-arterial therapy for acute ischemic stroke: a golden age

OPINION STATEMENT

With the recent publication of multiple trials demonstrating the superiority of the endovascular treatment of patients presenting with stroke from large vessel occlusion (LVO) over medical management, the emergent care of these patients is entering a new era. This realization justifies an aggressive treatment approach with these stroke patients, given the poor natural history of the disease. In general, treatment should occur as quickly as is reasonably possible. Patients with NIHSS >8 should be considered, and if <6 h from onset imaging selection achieved with CT and CTA. Those with ASPECTS >5, LVO and intermediate or good collaterals should be treated emergently. For patients with clinical deficits presenting in later timeframes MRI should be used to define core infarct size and therefore treatment eligibility. MRI might also be considered for the workup of stroke patients in centers that can offer it rapidly. Recanalization should be attempted with a stentriever or using a direct aspiration technique, with the patient under conscious sedation rather than general anesthesia, if that is a safe option. Angiographically, the goal is reperfusion of mTICI 2b/3. Post-procedure, the patient should be admitted to an intensive care setting and assessed for inpatient rehabilitation placement as soon as stable. Continuous institutional process improvement ensures that optimization of treatment times and logistics is an ongoing endeavor. Finally, patient outcomes should be assessed at three months, most commonly using the modified Rankin score.

Stroke Neurologist's Perspective on the New Endovascular Trials

Before December 2014, the only proven effective treatment for acute ischemic stroke was recombinant tissue-type plasminogen activator (r-tPA). This has now changed with the publication of the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times (ESCAPE), Extending the Time for Thrombolysis in Emergency Neurological Deficits--Intra-Arterial (EXTEND IA), Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment Trial (SWIFT PRIME), and Randomized Trial of Revascularization With the Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset (REVASCAT) studies. We review the main results of these studies and how they inform stroke patient management going forward. The main take home points for neurologists are (1) intra-arterial thrombectomy is a potently effective treatment and should be offered to patients who have documented occlusion in the distal internal carotid or the proximal middle cerebral artery, have a relatively normal noncontrast head computed tomographic scan, severe neurological deficit, and can have intra-arterial thrombectomy within 6 hours of last seen normal; (2) benefits are clear in patients receiving r-tPA before intra-arterial thrombectomy; r-tPA should not be withheld if the patient meets criteria, and benefit in patients who do not receive r-tPA or have r-tPA exclusions requires further study; and (3) these favorable results occur when intra-arterial thrombectomy is performed in an endovascular stroke center by a coordinated multidisciplinary team that extends from the prehospital stage to the endovascular suite, minimizes time to recanalization, uses stent-retriever devices, and avoids general anesthesia. In conclusion, stroke teams, including practicing neurologists caring for patients with stroke should now provide the option for intra-arterial thrombectomy for a subset of patients with acute stroke.

Role of imaging in current acute ischemic stroke workflow for endovascular therapy

Ischemic stroke is caused by a thrombus that blocks an intracranial artery. Brain tissue beyond the blocked artery survives for a variable period of time because of blood and nutrients received through tiny vessels called collaterals. Imaging the brain and the vasculature that supplies it is therefore a vital first step in treating patients with acute ischemic stroke. In this review, we focus on current evidence for imaging selection of patients for endovascular therapy in the context of the recently positive clinical trials, such as Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands (MR CLEAN), Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing Computed Tomography to Recanalization Times (ESCAPE), Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME), and Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA). We discuss evidence for and use of the various imaging paradigms available. We discuss how to set up quick and efficient imaging protocols for patient selection and address common concerns about the use of imaging, including time spent, contrast, radiation, and other advantages and disadvantages. Finally, we briefly comment on how imaging can integrate itself within various health systems of care in the future, thereby potentially improving patient outcomes further.