Ambulance Clinical Triage for Acute Stroke Treatment

Journal Club: Prehospital Detection of Large Vessel Occlusion Stroke With Electroencephalography: Results of the ELECTRA-STROKE Study

The ELECTRA-STROKE study investigated the potential of EEG for prehospital triage of patients with ischemic stroke due to large vessel occlusion (LVO), in which fast triage to stroke centers for endovascular treatment is crucial. The study was conducted in 4 phases, and this Journal Club article focuses on the fourth phase in the prehospital setting with suspected stroke patients. An EEG cap with dry electrodes was used to measure brain activity. The main focus was on the diagnostic accuracy of the theta/alpha ratio, which yielded an area under the receiver operator characteristic curve (AUC) of 0.80. Secondary endpoints, particularly the Brain Symmetry Index (a quantified EEG interhemispheric cortical power asymmetry index) in the delta frequency band, showed an AUC of 0.91. Despite the convenient study design and user-friendly EEG device, limitations include a single-arm design, a relatively small sample size, and exclusions due to data quality issues. The usefulness of EEG in the detection of neuronal changes based on brain ischemia was highlighted, but uncertainties remain regarding its use in certain patient groups. The improvements in the Brain Symmetry Index from phase 3 to 4 of the study indicate the potential for further refinement and investigation of combined methods to improve diagnostic accuracy. The study provides insight into the role of EEG in prehospital stroke detection, recognizing both the strengths and limitations. Overall, the study contributes to understanding the promise of EEG in optimizing LVO stroke triage and urges further refinement and exploration of complementary diagnostic approaches.

Identification of Anterior Large Vessel Occlusion Stroke During the Emergency Call: Protocol for a Controlled, Nonrandomized Trial

BACKGROUND

Endovascular thrombectomy (ET), combined with intravenous thrombolysis if possible, is an effective treatment option for patients with stroke who have confirmed anterior large vessel occlusion (aLVO). However, ET is mainly limited to comprehensive stroke centers (CSCs), resulting in a lack of ET capacity in remote, sparsely populated areas. Most stroke networks use the "Drip and Ship" or "Mothership" strategy, resulting in either delayed ET or intravenous thrombolysis, respectively.

OBJECTIVE

This study protocol introduces the Leitstellen-Basierte Erkennung von Schlaganfall-Patienten für eine Thrombektomie und daraufhin abgestimmte Optimierung der Rettungskette (LESTOR) strategy, developed to optimize the preclinical part of the stroke chain of survival to improve the clinical outcome of patients with suspected aLVO stroke. This involves refining the dispatch strategy for identifying patients with acute aLVO stroke using a phone-based aLVO query. This includes dispatching emergency physicians and emergency medical services (EMS) to urban emergency sites, as well as dispatching helicopter EMS to remote areas. If a highly suspected aLVO is identified after a standardized aLVO score evaluation during a structured examination at the emergency scene, prompt transport to a CSC should be prioritized.

METHODS

The LESTOR study is a controlled, nonrandomized study implementing the LESTOR strategy, with a stepped-wedge, cluster trial design in 6 districts in southwest Germany. In an interprofessional, iterative approach, an aLVO query or dispatch protocol intended for use by dispatchers, followed by a coordinated aLVO examination score for use by EMS, is being developed, evaluated, and pretested in a simulation study. After the training of all participating health care professionals with the corresponding final aLVO query, the LESTOR strategy is being implemented stepwise. Patients otherwise receive usual stroke care in both the control and intervention groups. The primary outcome is the modified Rankin Scale at 90 days in patients with stroke receiving endovascular treatment. We will use a generalized linear mixed model for data analysis. This study is accompanied by a cost-effectiveness analysis and a qualitative process evaluation.

RESULTS

This paper describes and discusses the protocol for this controlled, nonrandomized LESTOR study. Enrollment was completed in June 2023. Data analysis is ongoing and the first results are expected to be submitted for publication in 2024. The project started in April 2020 and will end in February 2024.

CONCLUSIONS

We expect that the intervention will improve the clinical outcome of patients with aLVO stroke, especially outside the catchment areas of CSCs. The results of the accompanying process evaluation and the cost-effectiveness analysis will provide further insights into the implementation process and allow for a better interpretation of the results.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00022152; https://drks.de/search/de/trial/DRKS00022152.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51683.

Comparison between different referral strategies for acute ischemic stroke patients in a hub-spoke emergency stroke network: a real-world experience in south-east Lazio

AIM

To describe different referral strategies for acute ischemic stroke (AIS) patients in a Hub-Spoke emergency stroke network with their incidence, time metrics and related outcomes.

METHODS

Referral paradigms were defined as follows: primary transfer to the comprehensive stroke center (CSC) from a remote region, called mothership (MS); secondary transfer to the CSC from a primary stroke center where intravenous thrombolysis was available, called drip and ship (DS); secondary transfer to the CSC from a community hospital where no reperfusion therapy was available, called ship and drip (SD); primary transfer to the CSC from its catchment area, called direct CSC (dCSC).

RESULTS

Among 517 anterior circulation AIS patients treated with mechanical thrombectomy between 2015 and 2020, 16.6% of them were SD, in addition to the well-known referral paradigms of MS (21.8%) and DS (18.1%). This rate grew to 30% when only patients whose place of onset was outside the CSC catchment area were considered. In the SD group, onset to CSC and onset to groin were significantly longer (178±80 min vs. 102±60 min, p<0.001, and 277±77 min vs. 211±61 min, p<0.001, respectively), and the risk of any intracranial hemorrhage (ICH) was significantly higher (OR: 2.514; 95%CI: 1.18-5.35, p=0.017) compared to MS.

CONCLUSION

In this hub-spoke stroke network, a high proportion of SD paradigm was found, which was associated with longer times to treatment and higher rates of any ICH. A closer cooperation between hospital stroke physicians, national health system staff, and paramedics is warranted to identify the most appropriate referral strategy for each patient.

Current and future trends in acute ischemic stroke treatment: direct-to-angiography suite, middle vessel occlusion, large core, and minor strokes

Since the publication of the landmark thrombectomy trials in 2015, the field of endovascular therapy for ischemic stroke has been rapidly growing. The very low number needed to treat to provide functional benefits shown by the initial randomized trials has led clinicians and investigators to seek to translate the benefits of endovascular therapy to other patient subgroups. Even if the treatment effect is diminished, currently available data has provided sufficient information to extend endovascular therapy to large infarct core patients. Recently, published data have also shown that sophisticated imaging is not necessary for late time- window patients. As a result, further research into patient selection and the stroke pathway now focuses on dramatically reducing door-to-groin times and improving outcomes by circumventing classical imaging paradigms altogether and employing a direct-to-angio suite approach for selected large vessel occlusion patients in the early time window. While the results of this approach mainly concern patients with severe deficits, there are further struggles to provide evidence of the efficacy and safety of endovascular treatment in minor stroke and large vessel occlusion, as well as in patients with middle vessel occlusions. The current lack of good quality data regarding these patients provides significant challenges for accurately selecting potential candidates for endovascular treatment. However, current and future randomized trials will probably elucidate the efficacy of endovascular treatment in these patient populations.

Derivation and validation of a predictive scale to expedite endovascular intervention for acute stroke patients with an intervenable vessel occlusion

BACKGROUND

Early endovascular intervention team mobilization may reduce reperfusion times and improve clinical outcomes for patients with acute ischemic stroke (AIS) with a possible intervenable vessel occlusion (IVO). In an emergency department or mobile stroke unit, incorporating rapidly available non-contrast CT (NCCT) information with examination findings may improve the accuracy of arterial occlusion prediction scales. For this purpose, we developed a rapid and straightforward IVO predictive instrument-the T3AM2PA1 scale.

METHODS

The T3AM2PA1 scale was retrospectively derived from our 'Get with the Guidelines' database. We included all patients with acute stroke alert between January 2017 and August 2018 with a National Institutes of Health Stroke Scale (NIHSS) score between 5 and 25 inclusive. Different pre-intervention variables were collected, including itemized NIHSS and NCCT information. The T3AM2PA1 scale was also compared with other commonly used scales and was validated in a separate sequential retrospective cohort of patients with a full range of NIHSS scores.

RESULTS

574 eligible patients from 2115 acute stroke alerts were identified. The scale was established with five items (CT hyperdense sign, parenchymal hypodensity, lateralizing hemiparesis, gaze deviation, and language disturbance), with a total score of 9. To minimize unnecessary angiography, a cut-off of ≥5 for IVO detection yielded a sensitivity of 52%, a specificity of 90%, and a positive predictive value of 76%.

CONCLUSIONS

The T3AM2PA1 scale accurately predicts the presence of clinical IVO in patients with AIS. Adopting the T3AM2PA1 scale could reduce revascularization times, improve treatment outcomes, and potentially reduce disability.

Impact of prehospital stroke triage implementation on patients with intracerebral hemorrhage

Background

Little is known about how prehospital triage using large vessel occlusion (LVO) stroke prediction scales affects patients with intracerebral hemorrhage (ICH).

Objectives

We aimed to investigate whether the Stockholm Stroke Triage System (SSTS) implemented in 2017 has affected timing and outcomes of acute ICH neurosurgery, and to assess system triage accuracy for ICH with a neurosurgical indication or LVO thrombectomy.

Design

Observational cohort study.

Methods

In the Stockholm Region, we compared surgical timing, functional outcome, and death at 3 months in patients transported by code-stroke ground ambulance who had ICH neurosurgery, 2 years before versus 2 years after SSTS implementation. We also calculated triage precision metrics for treatment with either ICH neurosurgery or thrombectomy.

Results

A total of 36 patients undergoing ICH neurosurgery were included before SSTS implementation and 30 after. No significant difference was found in timing of neurosurgery [median 7.5 (4.9-20.7) versus 9.1 (6.1-12.5) h after onset], distribution of functional outcomes (median 4 versus 4), and death at 3 months [3/29 (9%) versus 5/35 (17%)] before versus after implementation, respectively. The SSTS routed a larger proportion of patients subsequently undergoing ICH neurosurgery directly to the comprehensive stroke center: 13/36 (36%) before versus 18/30 (60%) after implementation. Overall system triage accuracy for ICH neurosurgery or thrombectomy was high at 90%, with 92% specificity and 65% sensitivity.

Conclusion

The SSTS, initially designed for prehospital LVO stroke triage, routed more patients with neurosurgical indication for ICH directly to the comprehensive stroke center. This did not significantly affect surgical timing or outcomes.

The Hunter-8 scale prehospital triage workflow for identification of large vessel occlusion and brain haemorrhage

ObjectiveThe Hunter-8 prehospital stroke scale predicts large vessel occlusion in hyperacute ischemic stroke patients (LVO) at hospital admission. We wished to test its performance in the hands of paramedics as part of a prehospital triage algorithm. We aimed to determine a) the proportion of patients identified by the Hunter-8 algorithm, receiving reperfusion therapies, b) whether a call to stroke team improved this, and c) performance for LVO detection using an expanded LVO definition.MethodsA prehospital workflow combining pre-morbid functional status, time from symptom onset, and the Hunter-8 scale was implemented from July 2019. A telephone call to the stroke team was prompted for potential treatment candidates. Classic LVO was defined as a proximal middle cerebral artery (MCA-M1), terminal internal carotid artery, or tandem occlusion. Extended LVO added proximal MCA-M2 and basilar occlusions.ResultsFrom July 2019 to April 2021, there were 363 Hunter-8 activations, 320 analysed: 181 (56.6%) had confirmed ischemic strokes, 13 (4.1%) transient ischemic attack, 91 (28.5%) stroke mimics, and 35 (10.9%) intracranial haemorrhage. Fifty-two patients (16.3%) received reperfusion therapies, 35 with Hunter-8 ≥ 8. The stroke doctor changed the final destination for 76 patients (23.7%), and five received reperfusion therapies. The AUCs for classic and extended LVO were 0.73 (95% CI 0.66-0.79) and 0.72 (95% CI 0.65-0.77), respectively.ConclusionThe Hunter-8 workflow resulted in 28.7% of confirmed ischemic stroke patients receiving reperfusion therapies, with no secondary transfers to the comprehensive stroke centre. The role of communication with stroke team needs to be further explored.

Practical utility of the ACT-FAST triage algorithm from a primary stroke centre perspective

Background: Rapid reperfusion in ischaemic stroke with emergent large vessel occlusion (ELVO) reduces morbidity and mortality. Limited distribution of endovascular clot retrieval (ECR) capable comprehensive stroke centres (CSCs) necessitates development of pre-hospital models of care to provide equitable and economical access to reperfusion therapy. We examine the time metrics of the traditional secondary transfer strategy in comparison to the direct bypass strategy and the potential utility of the ACT-FAST prehospital triage algorithm on a large volume Melbourne primary stroke centre (PSC).

Method: Retrospective analysis of consecutive patients presenting to a PSC from 1 January 2020 to 31 December 2020. Clinical records were interrogated for ACT-FAST positive patients. Time metrics were established using Google Maps traffic modelling and local/published door-to-needle, door-in-door out and door-to-groin data.

Results: 88 patients during the study period were ACT-FAST positive. Of these, 49/88 (56%) cases had ELVO ischaemic strokes, 24/88 (27%) cases had intracranial haemorrhages and the remaining 15/88 (17%) had non ELVO ischaemic strokes or mimics (seizure, complex migraine, etc). 28/88 (32%) cases met indication for and were subsequently transferred to a CSC for consideration of ECR. The modelled median scene to groin time for the direct bypass strategy is 94 min whereas the median scene to groin time for the secondary transfer strategy is 109 min, giving a difference of 15 min.

Conclusion: Time savings to groin puncture for the direct bypass strategy is substantially less than previous estimates and suggests that the secondary transfer strategy continues to be a viable pathway for a high efficiency PSC.

Cortical symptoms described in emergency calls for patients with suspected large vessel occlusion: a descriptive analysis of 157 emergency calls

Background

Emergency medical dispatchers typically use the dispatch code for suspected stroke when the caller brings up one or more symptoms from the face-arm-speech triad. Paramedics and emergency department physicians are trained to suspect large vessel occlusion stroke when the stroke patient presents with hemiparesis and cortical symptoms: neglect, aphasia, and conjugate eye deviation (CED). We hypothesized that these symptoms could be evident in the emergency call.

In this study, we aimed to describe common symptoms mentioned in the emergency calls for paramedic-suspected thrombectomy candidates. Secondly, we wanted to explore how the question about CED arises in the Finnish suspected stroke dispatch protocol. Our third aim was to find out if the symptoms brought up in suspected stroke and non-stroke dispatches differed from each other.

Methods

This was a retrospective study with a descriptive analysis of emergency calls for patients with paramedic-suspected large vessel occlusion stroke. We listened to the emergency calls for 157 patients transported to Tampere University Hospital, a Finnish comprehensive stroke centre. Two researchers listened for symptoms brought up in these calls and filled out a pre-planned case report form.

Results

Speech disturbance was the most common symptom brought up in 125 (80%) calls. This was typically described as an inability to speak any words (n = 65, 52% of calls with speech disturbance). Other common symptoms were falling down (n = 63, 40%) and facial asymmetry (n = 41, 26%). Suspicion of stroke was mentioned by 44 (28%) callers. When the caller mentioned unconsciousness the emergency dispatcher tended to use a non-stroke dispatch code. The dispatchers adhered poorly to the protocol and asked about CED in only 57% of suspected stroke dispatches. We found CED in 12 emergency calls and ten of these patients were diagnosed with large vessel occlusion.

Conclusion

In cases where paramedics suspected large vessel occlusion stroke, typical stroke symptoms were described during the emergency call. Speech disturbance was typically described as inability to say anything. It is possible to further develop suspected stroke dispatch protocols to recognize thrombectomy candidates from ischemic cortical signs such as global aphasia and CED.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12873-022-00706-5.

Large vessel occlusion prediction scales provide high negative but low positive predictive values in prehospital suspected stroke patients

Introduction

We studied a registry of Emergency Medical Systems (EMS) identified prehospital suspected stroke patients brought to an academic endovascular capable hospital over 1 year to assess the prevalence of disease and externally validate large vessel occlusion (LVO) stroke prediction scales with a focus on predictive values.

Methods

All patients had last known well times within 6 hours and a positive prehospital Cincinnati Prehospital Stroke Scale. LVO prediction scale scores were retrospectively calculated from emergency department arrival National Institutes of Health Stroke Scale scores. Final diagnoses were determined by chart review. Prevalence and diagnostic performance statistics were calculated. We prespecified analyses to identify scale thresholds with positive predictive values (PPVs) ≥80% and negative predictive values (NPVs) ≥95%. A secondary analysis identified thresholds with PPVs ≥50%.

Results

Of 220 EMS transported patients, 13.6% had LVO stroke, 15.9% had intracranial haemorrhage, 20.5% had non-LVO stroke and 50% had stroke mimic diagnoses. LVO stroke prevalence was 15.8% among the 184 diagnostic performance study eligible patients. Only Field Assessment Stroke Triage for Emergency Destination (FAST-ED) ≥7 had a PPV ≥80%, but this threshold missed 83% of LVO strokes. FAST-ED ≥6, Prehospital Acute Severity Scale =3 and Rapid Arterial oCclusion Evaluation ≥7 had PPVs ≥50% but sensitivities were <50%. Several standard and lower alternative scale thresholds achieved NPVs ≥95%, but false positives were common.

Conclusions

Diagnostic performance tradeoffs of LVO prediction scales limited their ability to achieve high PPVs without missing most LVO strokes. Multiple scales provided high NPV thresholds, but these were associated with many false positives.

Analysis and modelling of mistriage in the Stockholm stroke triage system

INTRODUCTION

The Stockholm Stroke Triage System (SSTS) is a prehospital triage system for detection of patients eligible for endovascular thrombectomy (EVT). Assessment of hemiparesis combined with ambulance-hospital teleconsultation is used to route patients directly to the thrombectomy centre. Some patients are not identified and require secondary transport for EVT (undertriage) while others taken to the thrombectomy centre do not undergo EVT (overtriage). The aims of this study were to characterize mistriaged patients, model for and evaluate alternative triage algorithms.

PATIENTS AND METHODS

Patients with suspected stroke transported by priority 1 ground ambulance between October 2017 and October 2018 (n = 2905) were included. Three triage algorithms were modelled using prehospital data. Decision curve analysis was performed to calculate net benefit (correctly routing patients for EVT without increasing mistriage) of alternative models vs SSTS.

RESULTS

Undertriage for EVT occurred in n = 35/2582 (1.4%) and overtriage in n = 239/323 (74.0%). Compared to correct thrombectomy triages, undertriaged patients were younger and had lower median NIHSS (10 vs 18), despite 62.9% with an M1 occlusion. In overtriaged patients, 77.0% had a stroke diagnosis (29.7% haemorrhagic). Hemiparesis and FAST items face and speech were included in all models. Decision curve analysis showed highest net benefit for SSTS for EVT, but lower for large artery occlusion (LAO) stroke.

DISCUSSION

Undertriaged patients had lower NIHSS, likely due to better compensated proximal occlusions. SSTS was superior to other models for identifying EVT candidates, but lacked information allowing comparison to other prehospital scales.

CONCLUSION

Using prehospital data, alternative models did not outperform the SSTS in finding EVT candidates.

The FAST VAN for Field Identification of Large Vessel Occlusion in Acute Stroke

BACKGROUND

There is definitive evidence for effectiveness of thrombectomy for acute stroke with large vessel occlusion (LVO). A clinical tool to identify patients with LVO is therefore required for effective triage and prehospital decision making. We developed the FAST VAN tool, which follows from the Heart and Stroke Foundation FAST stroke screen, with the addition of cortical features of vision, aphasia, and neglect, to differentiate from lacunar syndromes.

METHODS

Consecutive acute stroke alerts initiated by emergency medical services (EMS) were prospectively analyzed from April 2017 to Jan 2021. FAST VAN signs were recorded by first responders who had received online education about the tool. These findings were compared to the presence or absence of LVO on CT angiography. Analysis was also performed by appropriateness for comprehensive stroke centers (CSC) transfer if no LVO was present. EMS providers were surveyed regarding ease of use in terms of learning the tool and using in real-world practice.

RESULTS

Data from 1080 consecutive acute strokes included 440 patients considered to have VAN signs by EMS. Fifty-four percent of VAN-positive patients showed LVO on CTA. Sensitivity, specificity, and accuracy were 86%, 75%, and 77%, respectively. In 204 false-positive cases, 143 (70%) were considered appropriate for evaluation at the CSC. EMS providers reported high satisfaction with learning and using the tool.

DISCUSSION

The FAST VAN tool for identification of LVO meets desired characteristics of an effective screening tool in ease of use, efficiency, and accuracy. Aphasia remains the most challenging cortical feature to identify accurately.

Long-Term Cost-Effectiveness of Severity-Based Triaging for Large Vessel Occlusion Stroke

Background and Purpose:

Pre-hospital severity-based triaging using the Ambulance Clinical Triage For Acute Stroke Treatment (ACT-FAST) algorithm has been demonstrated to substantially reduce time to endovascular thrombectomy in Melbourne, Australia. We aimed to model the cost-effectiveness of an ACT-FAST bypass system from the healthcare system perspective.

Methods

A simulation model was developed to estimate the long-term costs and health benefits associated with diagnostic accuracy of the ACT-FAST algorithm. Three-month post stroke functional outcome was projected to the lifetime horizon to estimate the long-term cost-effectiveness between two strategies (ACT-FAST vs. standard care pathways). For ACT-FAST screened true positives (i.e., screened positive and eligible for EVT), a 52 mins time saving was applied unanimously to the onset to arterial time for EVT, while 10 mins delay in thrombolysis was applied for false-positive (i.e., screened positive but was ineligible for EVT) thrombolysis-eligible infarction. Quality-adjusted life year (QALY) was employed as the outcome measure to calculate the incremental cost-effectiveness ratio (ICER) between the ACT-FAST algorithm and the current standard care pathway.

Results

Over the lifetime, ACT-FAST was associated with lower costs (–$45) and greater QALY gains (0.006) compared to the current standard care pathway, resulting in it being the dominant strategy (less costly but more health benefits). Implementing ACT-FAST triaging led to higher proportion of patients received EVT procedure (30 more additional EVT performed per 10,000 patients). The total Net Monetary Benefit from ACT-FAST care estimated at A$0.76 million based on its implementation for a single year.

Conclusions

An ACT-FAST severity-triaging strategy is associated with cost-saving and increased benefits when compared to standard care pathways. Implementing ACT-FAST triaging increased the proportion of patients who received EVT procedure due to more patients arriving at EVT-capable hospitals within the 6-h time window (when imaging selection is less rigorous).

The Prehospital Stroke Score and telephone conference: A prospective validation

OBJECTIVES

The main aim of the study is to investigate the performance of a two-part stroke scale for screening and subsequent severity assessment combined with a telephone conference (teleconference).

MATERIALS AND METHODS

During a 6-month period, we prospectively tested the Prehospital Stroke Score (PreSS). PreSS part 1 is designed to identify stroke or TIA in a prehospital setting. PreSS part 2 is a stroke severity scale designed to identify large-vessel occlusion (LVO). PreSS was performed by emergency medical service (EMS) providers prior to a teleconference with a stroke neurologist.

RESULTS

Combined teleconference and PreSS part 1 were performed on 79.3% of all patients diagnosed with stroke/TIA, and 99.1% of the patients with positive scores were subsequently PreSS part 2 scored. PreSS part 1 and teleconference had a sensitivity to identify stroke/TIA of 89.3% (95% CI 85.7-92.2), specificity of 64.5% (95% CI 59.3-69.5), and an area under the curve (AUC) of 0.80 (95% CI 0.77-0.83). Regarding LVO, PreSS part 1 with teleconference recognized 96.7% (95% CI 88.7-99.6) of all cases as stroke. PreSS part 2 had a sensitivity of 55.7% (95% CI 42.4-68.5), specificity of 91.5% (95% CI 89.0-93.6), and AUC of 0.86 (95% CI 0.82-0.90) for identification of LVO.

CONCLUSIONS

PreSS was feasible and the sensitivity for stroke/TIA and LVO was high to moderate providing an overall high precision. Almost all LVO cases were ensured acute stroke admission. The high specificity for LVO could be useful for determining transfers strategies.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence when evaluating PreSS combined with teleconference.

Emerging Detection Techniques for Large Vessel Occlusion Stroke: A Scoping Review

Background: Large vessel occlusion (LVO) is the obstruction of large, proximal cerebral arteries and can account for up to 46% of acute ischaemic stroke (AIS) when both the A2 and P2 segments are included (from the anterior and posterior cerebral arteries). It is of paramount importance that LVO is promptly recognised to provide timely and effective acute stroke management. This review aims to scope recent literature to identify new emerging detection techniques for LVO. As a good comparator throughout this review, the commonly used National Institutes of Health Stroke Scale (NIHSS), at a cut-off of ≥11, has been reported to have a sensitivity of 86% and a specificity of 60% for LVO. Methods: Four electronic databases (Medline via OVID, CINAHL, Scopus, and Web of Science), and grey literature using OpenGrey, were systematically searched for published literature investigating developments in detection methods for LVO, reported from 2015 to 2021. The protocol for the search was published with the Open Science Framework (10.17605/OSF.IO/A98KN). Two independent researchers screened the titles, abstracts, and full texts of the articles, assessing their eligibility for inclusion. Results: The search identified 5,082 articles, in which 2,265 articles were screened to assess their eligibility. Sixty-two studies remained following full-text screening. LVO detection techniques were categorised into 5 groups: stroke scales (n = 30), imaging and physiological methods (n = 15), algorithmic and machine learning approaches (n = 9), physical symptoms (n = 5), and biomarkers (n = 3). Conclusions: This scoping review has explored literature on novel and advancements in pre-existing detection methods for LVO. The results of this review highlight LVO detection techniques, such as stroke scales and biomarkers, with good sensitivity and specificity performance, whilst also showing advancements to support existing LVO confirmatory methods, such as neuroimaging.

Validation of a shortened FAST-ED algorithm for smartphone app guided stroke triage

Background and Purpose:

Large vessel occlusion (LVO) recognition scales were developed to identify patients with LVO-related acute ischemic stroke (AIS) on the scene of emergency. Thus, they may enable direct transport to a comprehensive stroke centre (CSC). In this study, we aim to validate a smartphone app-based stroke triage with a shortened form of the Field Assessment Stroke Triage for Emergency Destination (FAST-ED).

Methods:

This retrospective validation study included 2815 patients with confirmed acute stroke and suspected acute stroke but final diagnosis other than stroke (stroke mimics) who were admitted by emergency medical service (EMS) to the CSC of the Neurological University Hospital Essen, Germany. We analysed the predictive accuracy of a shortened digital app-based FAST-ED ( ‘FAST-ED App’) for LVO-related AIS and yield comparison to various other LVO recognition scales.

Results:

The shortened FAST-ED App had comparable test quality (Area under ROC = 0.887) to predict LVO-related AIS to the original FAST-ED (0.889) and RACE (0.883) and was superior to Cincinnati Prehospital Stroke Severity (CPSS), 3-Item Stroke Scale (3-ISS) and National Institute of Health Stroke Scale (NIHSS). A FAST-ED App ⩾ 4 revealed very good accuracy to detect LVO related AIS (sensitivity of 77% and a specificity 87%) with an area under the curve c-statistics of 0.89 (95% CI: 0.87–0.90). In a hypothetical triage model, the number needed to screen in order to avoid one secondary transportation in an urban setting would be five.

Conclusion:

This validation study of a shortened FAST-ED assessment for a smartphone-app guided stroke triage yields good quality to identify patients with LVO.

Modeling the Impact of Prehospital Triage on a True-Life Drip and Ship Mechanical Thrombectomy Urban Patient Cohort

Objective

The aim of the study was to model the effect of prehospital triage of emergent large vessel occlusion (ELVO) to endovascular capable center (ECC) on the timing of thrombectomy and intravenous (IV) thrombolysis using real-world data from a multihospital system.

Methods

We selected a cohort of 77 consecutive stroke patients who were brought by emergency medical services (EMS) to a nonendovascular capable center and then transferred to an ECC for mechanical thrombectomy (MT) (“actual” drip and ship [DS] cohort). We created a hypothetical scenario (bypass model [BM]), modeling transfer of the patients directly to an ECC, based on patients' initial EMS pickup address and closest ECC. Using another cohort of 73 consecutive patients, who were brought directly to an ECC by EMS and underwent endovascular intervention, we calculated mean door-to-needle and door-to-arterial puncture (AP) times (“actual” mothership [MS] cohort). Timings in the actual MS cohort and the actual DS cohort were compared to timings from the BM cohort.

Results

Median first medical contact (FMC) to IV thrombolysis time was 87.5 min (interquartile range [IQR] = 38) for the DS versus 78.5 min (IQR = 8.96) for the BM cohort, with p = 0.1672. Median FMC to AP was 244 min (IQR = 97) versus 147 min (IQR = 8.96) (p < 0.001), and median FMC to TICI 2B+ time was 299 min (IQR = 108.5) versus 197 min (IQR = 8.96) (p < 0.001) for the DS versus BM cohort, respectively.

Conclusions

Modeled EMS prehospital triage of ELVO patients' results in shorter MT times without a change in thrombolysis times. As triage tools increase in sensitivity and specificity, EMS triage protocols stand to improve patient outcomes.

FAST-ED scale smartphone app-based prediction of large vessel occlusion in suspected stroke by emergency medical service

Background and Purpose:

Considering the highly time-dependent therapeutic effect of endovascular treatment in patients with large vessel occlusion–associated acute ischemic stroke, prehospital identification of large vessel occlusion and subsequent triage for direct transport to a comprehensive stroke center offers an intriguing option for optimizing patient pathways.

Methods:

This prospective in-field validation study included 200 patients with suspected acute ischemic stroke who were admitted by emergency medical service to a comprehensive stroke center. Ambulances were equipped with smartphones running an app-based Field Assessment Stroke Triage for Emergency Destination scale for transmission prior to admission. The primary measure was the predictive accuracy of the transmitted Field Assessment Stroke Triage for Emergency Destination for large vessel occlusion and the secondary measure the predictive accuracy for endovascular treatment.

Results:

A Field Assessment Stroke Triage for Emergency Destination ⩾4 revealed very good accuracy to detect large vessel occlusion–related acute ischemic stroke with a sensitivity of 82.4% (95% confidence interval = 65.5–93.2), specificity of 78.3% (95% confidence interval = 71.3–84.3), and an area under the curve c-statistics of 0.89 (95% confidence interval = 0.85–0.94). Field Assessment Stroke Triage for Emergency Destination ⩾4 correctly identified 84% of patients who received endovascular treatment [73.5% specificity (95% confidence interval = 66.4–79.8)] with an area under the curve c-statistics of 0.82 (95% confidence interval = 0.74–0.89). In a hypothetical triage model of an urban setting, one secondary transportation would be avoided with every fifth patient screened.

Conclusion:

A smartphone app-based stroke triage completed by emergency medical service personnel showed adequate quality for the Field Assessment Stroke Triage for Emergency Destination to identify large vessel occlusion–associated acute ischemic stroke. We demonstrate feasibility of the use of a medical messaging service in prehospital stroke care. Based on these first results, a randomized trial evaluating the clinical benefit of such a triage system in an urban setting is currently in preparation.

Clinical Trial Registration: https://clinicaltrials.gov Unique identifier: NCT04404504.

Prehospital Stroke Triage

PURPOSE OF THE REVIEW

This article reviews prehospital organization in the treatment of acute stroke. Rapid access to an endovascular therapy (EVT) capable center and prehospital assessment of large vessel occlusion (LVO) are 2 important challenges in acute stroke therapy. This article emphasizes the use of transfer protocols to assure the prompt access of patients with an LVO to a comprehensive stroke center where EVT can be offered. Available prehospital clinical tools and novel technologies to identify LVO are also discussed. Moreover, different routing paradigms like first attention at a local stroke center ("drip and ship"), direct transfer of the patient to an endovascular center ("mothership"), transfer of the neurointerventional team to a local primary center ("drip and drive"), mobile stroke units, and prehospital management communication tools all aimed to improve connection and coordination between care levels are reviewed.

RECENT FINDINGS

Local observational data and mathematical models suggest that implementing triage tools and bypass protocols may be an efficient solution. Ongoing randomized clinical trials comparing drip and ship vs mothership will elucidate which is the more effective routing protocol.

SUMMARY

Prehospital organization is critical in realizing maximum benefit from available therapies in acute stroke. The optimal transfer protocols directed to accelerate EVT are under study, and more accurate prehospital triage tools are needed. To improve care in the prehospital setting, efficient tools based on patient factors, local geography, and hospital capability are needed. These tools would optimally lead to individualized real-time decision-making.

Sensitivity of prehospital stroke scales for different intracranial large vessel occlusion locations

Introduction

Prehospital stroke scales have been proposed to identify stroke patients with a large vessel occlusion to allow direct transport to an intervention centre capable of endovascular treatment (EVT). It is unclear whether these scales are able to detect not only proximal, but also more distal treatable occlusions. Our aim was to assess the sensitivity of prehospital stroke scales for different EVT-eligible occlusion locations in the anterior circulation.

Patients and methods

The MR CLEAN Registry is a prospective, observational study in all centres that perform EVT in the Netherlands. We included adult patients with an anterior circulation stroke treated between March 2014 and November 2017. We used National Institutes of Health Stroke Scale scores at admission to reconstruct previously published prehospital stroke scales. We compared the sensitivity of each scale for different occlusion locations. Occlusions were assessed with CT angiography by an imaging core laboratory blinded to clinical findings.

Results

We included 3021 patients for the analysis of 14 scales. All scales had the highest sensitivity to detect internal carotid artery terminus occlusions (ranging from 0.21 to 0.97) and lowest for occlusions of the M2 segment (0.08 to 0.84, p-values < 0.001).Discussion and conclusion: Although prehospital stroke scales are generally sensitive for proximal large vessel occlusions, they are less sensitive to detect more distal occlusions.

Effects of state-wide implementation of the Los Angeles Motor Scale for triage of stroke patients in clinical practice

BACKGROUND

The prehospital identification of stroke patients with large-vessel occlusion (LVO), that should be immediately transported to a thrombectomy capable centre is an unsolved problem. Our aim was to determine whether implementation of a state-wide standard operating procedure (SOP) using the Los Angeles Motor Scale (LAMS) is feasible and enables correct triage of stroke patients to hospitals offering (comprehensive stroke centres, CSCs) or not offering (primary stroke centres, PSCs) thrombectomy.

METHODS

Prospective study involving all patients with suspected acute stroke treated in a 4-month period in a state-wide network of all stroke-treating hospitals (eight PSCs and two CSCs). Primary endpoint was accuracy of the triage SOP in correctly transferring patients to CSCs or PSCs. Additional endpoints included the number of secondary transfers, the accuracy of the LAMS for detection of LVO, apart from stroke management metrics.

RESULTS

In 1123 patients, use of a triage SOP based on the LAMS allowed triage decisions according to LVO status with a sensitivity of 69.2% (95% confidence interval (95%-CI): 59.0-79.5%) and a specificity of 84.9% (95%-CI: 82.6-87.3%). This was more favourable than the conventional approach of transferring every patient to the nearest stroke-treating hospital, as determined by geocoding for each patient (sensitivity, 17.9% (95%-CI: 9.4-26.5%); specificity, 100% (95%-CI: 100-100%)). Secondary transfers were required for 14 of the 78 (17.9%) LVO patients. Regarding the score itself, LAMS detected LVO with a sensitivity of 67.5% (95%-CI: 57.1-78.0%) and a specificity of 83.5% (95%-CI: 81.0-86.0%).

CONCLUSIONS

State-wide implementation of a triage SOP requesting use of the LAMS tool is feasible and improves triage decision-making in acute stroke regarding the most appropriate target hospital.

Differences in Characteristics and Ambulance Pathway Adherence Between Strokes and Mimics Presenting to a Large UK Centralized Hyper Acute Stroke Unit (HASU)

Background: In Greater Manchester (GM), prehospital clinicians use the Face Arm Speech Test (FAST) to identify suspected stroke patients alongside pathway exclusions. Within the centralized stroke service, patients with a suspected stroke are taken directly to a Hyper Acute Stroke Unit (HASU), often bypassing their local emergency department (ED). However, many of these patients are experiencing an illness that looks like a stroke but is not a stroke. The data collected in the prehospital setting is rarely used in research yet could give valuable insights into the performance of the pathway.

Aim: To evaluate the presenting symptoms and final diagnoses of prehospital suspected strokes and to evaluate the adherence of prehospital stroke pathway exclusions.

Methods: We analyzed data from all patients brought in by ambulance and admitted on the stroke pathway between 01/09/15 and 28/02/17. Patient demographics and all data recorded in the prehospital setting were evaluated to identify differences in stroke, TIA, and mimic patients. Pathway adherence was assessed according to whether the patient was local or out-of-area (OOA) and bypassed their local ED.

Results: A total of 4,216 suspected strokes were identified: 2,213 (52.5%) had a final diagnosis of stroke, 492 (11.7%) experienced a transient ischemic attack (TIA), and 1,511 (35.8%) were stroke mimics. There were 714 (16.9%) patients that were identified as having at least one pathway exclusion or were FAST negative, of which 270 (37.8%) experienced a stroke. The proportion of strokes was significantly lower in those with a pathway exclusion (41.8 vs. 53.5%; p < 0.001) and the proportion of breaches tended to be comparable or higher in the local population.

Discussion: There are high volumes of stroke mimics but identified differences indicate there is an opportunity to better utilize prehospital data. Ambulance clinicians were able to correctly overrule FAST negative results and the volume of these suggest that FAST alone may be too restrictive.

Prehospital Triage Accuracy in Patients With Stroke Symptoms Assessed Within 6 to 24 Hours or With an Unknown Time of Onset

BACKGROUND AND PURPOSE

The Stockholm Stroke Triage System, implemented in 2017, identifies patients with high likelihood of large vessel occlusion (LVO) stroke. A previous report has shown Stockholm Stroke Triage System notably reduced time to endovascular thrombectomy (EVT). As the indication for EVT now includes patients up to 24 hours, we aimed to assess Stockholm Stroke Triage System triage accuracy for LVO stroke and EVT treatment for patients presenting late (within 6-24 hours or with an unknown onset), put in contrast to triage accuracy within 0 to 6 hours.

METHODS

Between October 2017 and October 2018, we included 2905 patients with suspected stroke, transported by priority 1 ground ambulance to a Stockholm Region hospital. Patients assessed 6 to 24 hours from last known well or with unknown onset were defined as late-presenting; those within <6 hours as early-presenting. Triage positivity was defined as transport to comprehensive stroke center because of suspected stroke, hemiparesis and high likelihood of EVT-eligible LVO per teleconsultation.

RESULTS

Overall triage accuracy was high in late-presenting patients (90.9% for LVO, 93.9% for EVT), with high specificity (95.7% for LVO, 94.5% for EVT), and low to moderate sensitivity (34.3% for LVO, 64.7% for EVT), with similar findings in the early-presenting group.

CONCLUSIONS

Our results may support using the Stockholm Stroke Triage System for primary stroke center bypass in patients assessed by ambulance up to 24 hours from time of last known well.

Access to Endovascular Thrombectomy for Stroke in Rural Versus Urban Regions

PURPOSE

Endovascular thrombectomy (EVT) significantly improves outcomes for acute ischemic stroke patients with large vessel occlusion (LVO) who present in a time sensitive manner. Prolonged EVT access times may reduce benefits for eligible patients. We evaluated the efficiency of EVT services including EVT rates, onset-to-CTA time and onset-to-groin puncture time in our province.

MATERIALS AND METHODS

Three areas were defined: zone I- urban region, zone II-areas within 1 h drive distance from the Comprehensive Stroke Center (CSC); and zone III-areas more than 1hr drive distance from the CSC. In this retrospective cohort study, EVT rate, onset-to-groin puncture time and onset-to-CTA time were compared among the three groups using Krustal-Wallis and Wilcoxon tests.

RESULTS

The EVT rate per 100,000 inhabitants for urban zone I was 8.6 as compared to 5.1 in zone II, and 7.5 in zone III. Compared to zone I (114 min; 95% CI (96, 132); n = 128), mean onset-to-CTA time was 19 min longer in zone II (133 min; 95% CI (77, 189); n = 23; p = 0.0459) and 103 min longer in zone III (217 min, 95% CI (162, 272); n = 44; p < 0.0001). Compared to zone I (209 min, 95% CI (181, 238)), mean onset-to-groin puncture time was 22 min longer in zone II (231 min, 95% CI (174, 288); p = 0.046) but 163 min longer in zone III (372 min, 95% CI (312, 432); p < 0.0001).

CONCLUSION

EVT access in rural areas is considerably reduced with significantly longer onset-to-groin puncture times and onset-to-CTA times when compared to our urban area. This may help in modifying the patient transfer policy for EVT referral.

Implementation of a Prehospital Stroke Triage System Using Symptom Severity and Teleconsultation in the Stockholm Stroke Triage Study

Importance

To our knowledge, it is unknown whether a prehospital stroke triage system combining symptom severity and teleconsultation could accurately select patients for primary stroke center bypass and hasten delivery of endovascular thrombectomy (EVT) without delaying intravenous thrombolysis (IVT).

Objective

To evaluate the predictive performance of the newly implemented Stockholm Stroke Triage System (SSTS) for large-artery occlusion (LAO) stroke and EVT initiation. Secondary objectives included evaluating whether the Stockholm Stroke Triage System shortened onset-to-puncture time for EVT and onset-to-needle time (ONT) for IVT.

Design, Setting, and Participants

This population-based prospective cohort study conducted from October 2017 to October 2018 across the Stockholm region (Sweden) included patients transported by first-priority ("code stroke") ambulance to the hospital for acute stroke suspected by an ambulance nurse and historical controls (October 2016-October 2017). Exclusion criteria were in-hospital stroke and helicopter or private transport. Of 2909 eligible patients, 4 (0.14%) declined participation.

Exposures

Patients were assessed by ambulance nurses with positive the face-arm-speech-time test or other stroke suspicion and were evaluated for moderate-to-severe hemiparesis (≥2 National Institutes of Health stroke scale points each on the ipsilateral arm and leg [A2L2 test]). If present, the comprehensive stroke center (CSC) stroke physician was teleconsulted by phone for confirmation of stroke suspicion, assessment of EVT eligibility, and direction to CSC or the nearest primary stroke center. If absent, the nearest hospital was prenotified.

Main Outcomes and Measures

Primary outcome: LAO stroke. Secondary outcomes: EVT initiation, onset-to-puncture time, and ONT. Predictive performance measures included sensitivity, specificity, positive and negative predictive values, the overall accuracy for LAO stroke, and EVT initiation.

Results

We recorded 2905 patients with code-stroke transports (1420 women [49%]), and of these, 323 (11%) had A2L2+ teleconsultation positive results and were triaged for direct transport to CSC (median age, 73 years [interquartile range (IQR), 64-82 years]; 55 women [48%]). Accuracy for LAO stroke was 87% (positive predictive value, 41%; negative predictive value, 93%) and 91% for EVT initiation (positive predictive value, 26%; negative predictive value, 99%). Endovascular thrombectomy was performed for 84 of 323 patients (26%) with triage-positive results and 35 of 2582 patients (1.4%) with triage-negative results. In EVT cases with a known onset time (77 [3%]), the median OPT was 137 minutes (IQR, 118-180; previous year, 206 minutes [IQR, 160-280]; n = 75) (P < .001). The regional median ONT (337 [12%]) was unchanged at 115 minutes (IQR, 83-164; previous year, 115 minutes [IQR, 85-161]; n = 360) (P = .79). The median CSC IVT door-to-needle time was 13 minutes (IQR, 10-18; 116 [4%]) (previous year, 31 minutes [IQR, 19-38]; n = 45) (P < .001).

Conclusions and Relevance

The Stockholm Stroke Triage System, which combines symptom severity and teleconsultation, results in markedly faster EVT delivery without delaying IVT.

Comparison of Prehospital Scales for Predicting Large Anterior Vessel Occlusion in the Ambulance Setting

Importance

The efficacy of endovascular thrombectomy (EVT) for symptomatic large anterior vessel occlusion (sLAVO) sharply decreases with time. Because EVT is restricted to comprehensive stroke centers, prehospital triage of patients with acute stroke codes for sLAVO is crucial, and although several prediction scales are already in use, external validation, head-to-head comparison, and feasibility data are lacking.

Objective

To conduct external validation and head-to-head comparisons of 7 sLAVO prediction scales in the emergency medical service (EMS) setting and to assess scale feasibility by EMS paramedics.

Design, Setting, and Participants

This prospective cohort study was conducted between July 2018 and October 2019 in a large urban center in the Netherlands with a population of approximately 2 million people and included 2 EMSs, 3 comprehensive stroke centers, and 4 primary stroke centers. Participants were consecutive patients aged 18 years or older for whom an EMS-initiated acute stroke code was activated. Of 2812 acute stroke codes, 805 (28.6%) were excluded, because no application was used or no clinical data were available, leaving 2007 patients included in the analyses.

Exposures

Applications with clinical observations filled in by EMS paramedics for each acute stroke code enabling reconstruction of the following 7 prediction scales: Los Angeles Motor Scale (LAMS); Rapid Arterial Occlusion Evaluation (RACE); Cincinnati Stroke Triage Assessment Tool; Prehospital Acute Stroke Severity (PASS); gaze-face-arm-speech-time; Field Assessment Stroke Triage for Emergency Destination; and gaze, facial asymmetry, level of consciousness, extinction/inattention.

Main Outcomes and Measures

Planned primary and secondary outcomes were sLAVO and feasibility rates (ie, the proportion of acute stroke codes for which the prehospital scale could be reconstructed). Predictive performance measures included accuracy, sensitivity, specificity, the Youden index, and predictive values.

Results

Of 2007 patients who received acute stroke codes (mean [SD] age, 71.1 [14.9] years; 1021 [50.9%] male), 158 (7.9%) had sLAVO. Accuracy of the scales ranged from 0.79 to 0.89, with LAMS and RACE scales yielding the highest scores. Sensitivity of the scales ranged from 38% to 62%, and specificity from 80% to 93%. Scale feasibility rates ranged from 78% to 88%, with the highest rate for the PASS scale.

Conclusions and Relevance

This study found that all 7 prediction scales had good accuracy, high specificity, and low sensitivity, with LAMS and RACE being the highest scoring scales. Feasibility rates ranged between 78% and 88% and should be taken into account before implementing a scale.

Prehospital EMS Triage for Acute Stroke Care

Acute stroke has had major advances over the last two decades due to the introduction of pharmacologic and endovascular revascularization, which can improve functional outcome. Stroke systems of care have been developed to provide faster, more efficient care for stroke patients. A major part of these care pathways is prehospital care, when patients are triaged to appropriate levels of care. It is essential that prehospital scales are used accurately and effectively by emergency medical services to assist them with the triage process. New technologies including mobile stroke units, telemedicine, and wearable technology have been introduced as options for optimization of this emergent process.

Utility of Severity-Based Prehospital Triage for Endovascular Thrombectomy: ACT-FAST Validation Study

BACKGROUND AND PURPOSE

Severity-based assessment tools may assist in prehospital triage of patients to comprehensive stroke centers (CSCs) for endovascular thrombectomy (EVT), but criticisms regarding diagnostic inaccuracy have not been adequately addressed. This study aimed to quantify the benefits and disadvantages of severity-based triage in a large real-world paramedic validation of the Ambulance Clinical Triage for Acute Stroke Treatment (ACT-FAST) algorithm.

METHODS

Ambulance Victoria paramedics assessed the prehospital ACT-FAST algorithm in patients with suspected stroke from November 2017 to July 2019 following an 8-minute training video. All patients were transported to the nearest stroke center as per current guidelines. ACT-FAST diagnostic accuracy was compared with hospital imaging for the presence of large vessel occlusion (LVO) and need for CSC-level care (LVO, intracranial hemorrhage, and tumor). Patient-level time saving to EVT was modeled using a validated Google Maps algorithm. Disadvantages of CSC bypass examined potential thrombolysis delays in non-LVO infarcts, proportion of patients with false-negative EVT, and CSC overburdening.

RESULTS

Of 517 prehospital assessments, 168/517 (32.5%) were ACT-FAST positive and 132/517 (25.5%) had LVO. ACT-FAST sensitivity and specificity for LVO was 75.8% and 81.8%, respectively. Positive predictive value was 58.8% for LVO and 80.0% when intracranial hemorrhage and tumor (CSC-level care) were included. Within the metropolitan region, 29/55 (52.7%) of ACT-FAST-positive patients requiring EVT underwent a secondary interhospital transfer. Prehospital bypass with avoidance of secondary transfers was modeled to save 52 minutes (95% CI, 40.0-61.5) to EVT commencement. ACT-FAST was false-positive in 8 patients receiving thrombolysis (8.1% of 99 non-LVO infarcts) and false-negative in 4 patients with EVT requiring secondary transfer (5.4% of 74 EVT cases). CSC bypass was estimated to over-triage 1.1 patients-per-CSC-per-week in our region.

CONCLUSIONS

The overall benefits of an ACT-FAST algorithm bypass strategy in expediting EVT and avoiding secondary transfers are estimated to substantially outweigh the disadvantages of potentially delayed thrombolysis and over-triage, with only a small proportion of EVT patients missed.

Stroke systems of care in high-income countries: what is optimal?

Stroke is a complex, time-sensitive, medical emergency that requires well functioning systems of care to optimise treatment and improve patient outcomes. Education and training campaigns are needed to improve both the recognition of stroke among the general public and the response of emergency medical services. Specialised stroke ambulances (mobile stroke units) have been piloted in many cities to speed up the diagnosis, triage, and emergency treatment of people with acute stroke symptoms. Hospital-based interdisciplinary stroke units remain the central feature of a modern stroke service. Many have now developed a role in the very early phase (hyperacute units) plus outreach for patients who return home (early supported discharge services). Different levels (comprehensive and primary) of stroke centre and telemedicine networks have been developed to coordinate the various service components with specialist investigations and interventions including rehabilitation. Major challenges include the harmonisation of resources for stroke across the whole patient journey (including the rapid, accurate triage of patients who require highly specialised treatment in comprehensive stroke centres) and the development of technology to improve communication across different parts of a service.

Validity of a five-level prehospital triage system in Japan: A cohort study

BACKGROUND

The increasing worldwide demand for ambulance transport may worsen patient prognosis due to a prolonged response time and overcrowding in the emergency department. Triage in the prehospital setting may reduce the demand for ambulance transport by advising low-acuity patients seek non-emergency medical care. In Japan, a five-level triage system that allows emergency medical services (EMS) to triage patients has been implemented since 2014. This study aimed to validate the five-level triage system.

METHODS

We conducted a retrospective cohort study in patients aged ≥16 years who were transported by EMS to a tertiary-care hospital in Japan from April 2018 to June 2018. We used admission to the intensive care unit (ICU) as the primary outcome. Our secondary outcome was overall admission. We conducted multivariable logistic regression analysis to determine the strength of association between triage acuity and admission (ICU and overall).

RESULTS

A total of 1261 patients were included in the analysis. The odds ratios of ICU admission were 9.62 (95% confidence interval: 5.66-16.3) in Level 1 and 2.93 (95% confidence interval: 1.60-5.38) in Level 2 compared with reference groups composed of Levels 4 and 5. Similar associations were found for triage acuity and overall admission.

CONCLUSIONS

Our study validates the five-level prehospital triage system for patients transported by EMS and demonstrates an association between the triage acuity and ICU admissions.

Stroke

Stroke is a major cause of death and disability globally. Diagnosis depends on clinical features and brain imaging to differentiate between ischaemic stroke and intracerebral haemorrhage. Non-contrast CT can exclude haemorrhage, but the addition of CT perfusion imaging and angiography allows a positive diagnosis of ischaemic stroke versus mimics and can identify a large vessel occlusion target for endovascular thrombectomy. Management of ischaemic stroke has greatly advanced, with rapid reperfusion by use of intravenous thrombolysis and endovascular thrombectomy shown to reduce disability. These therapies can now be applied in selected patients who present late to medical care if there is imaging evidence of salvageable brain tissue. Both haemostatic agents and surgical interventions are investigational for intracerebral haemorrhage. Prevention of recurrent stroke requires an understanding of the mechanism of stroke to target interventions, such as carotid endarterectomy, anticoagulation for atrial fibrillation, and patent foramen ovale closure. However, interventions such as lowering blood pressure, smoking cessation, and lifestyle optimisation are common to all stroke subtypes.

Factors delaying intravenous thrombolytic therapy in acute ischaemic stroke: a systematic review of the literature

BACKGROUND/AIMS

This review examined factors that delay thrombolysis and what management strategies are currently employed to minimise this delay, with the aim of suggesting future directions to overcome bottlenecks in treatment delivery.

METHODS

A systematic review was performed according to PRISMA guidelines. The search strategy included a combination of synonyms and controlled vocabularies from Medical Subject Headings (MeSH) and EmTree covering brain ischemia, cerebrovascular accident, fibrinolytic therapy and Alteplase. The search was conducted using Medline (OVID), Embase (OVID), PubMed and Cochrane Library databases using truncations and Boolean operators. The literature search excluded review articles, trial protocols, opinion pieces and case reports. Inclusion criteria were: (1) The article directly related to thrombolysis in ischaemic stroke, and (2) The article examined at least one factor contributing to delay in thrombolytic therapy.

RESULTS

One hundred and fifty-two studies were included. Pre-hospital factors resulted in the greatest delay to thrombolysis administration. In-hospital factors relating to assessment, imaging and thrombolysis administration also contributed. Long onset-to-needle times were more common in those with atypical, or less severe, symptoms, the elderly, patients from lower socioeconomic backgrounds, and those living alone. Various strategies currently exist to reduce delays. Processes which have achieved the greatest improvements in time to thrombolysis are those which integrate out-of-hospital and in-hospital processes, such as the Helsinki model.

CONCLUSION

Further integrated processes are required to maximise patient benefit from thrombolysis. Expansion of community education to incorporate less common symptoms and provision of alert pagers for patients may provide further reduction in thrombolysis times.

Melbourne Mobile Stroke Unit and Reperfusion Therapy

Background and Purpose—

Mobile stroke units (MSUs) are increasingly used worldwide to provide prehospital triage and treatment. The benefits of MSUs in giving earlier thrombolysis have been well established, but the impacts of MSUs on endovascular thrombectomy (EVT) and effect on disability avoidance are largely unknown. We aimed to determine the clinical impact and disability reduction for reperfusion therapies in the first operational year of the Melbourne MSU.

Methods—

Treatment time metrics for MSU patients receiving reperfusion therapy were compared with control patients presenting to metropolitan Melbourne stroke units via standard ambulance within MSU operating hours. The primary outcome was median time difference in first ambulance dispatch to treatment modeled using quantile regression analysis. Time savings were subsequently converted to disability-adjusted life years avoided using published estimates.

Results—

In the first 365-day operation of the Melbourne MSU, prehospital thrombolysis was administered to 100 patients (mean age, 73.8 years; 62% men). The median time savings per MSU patient, compared with the control cohort, was 26 minutes ( P <0.001) for dispatch to hospital arrival and 15 minutes ( P <0.001) for hospital arrival to thrombolysis. The calculated overall time saving from dispatch to thrombolysis was 42.5 minutes (95% CI, 36.0–49.0). In the same period, 41 MSU patients received EVT (mean age, 76 years; 61% men) with median dispatch-to-treatment time saving of 51 minutes ([95% CI, 30.1–71.9], P <0.001). This included a median time saving of 17 minutes ([95% CI, 7.6–26.4], P =0.001) for EVT hospital arrival to arterial puncture for MSU patients. Estimated median disability-adjusted life years saved through earlier provision of reperfusion therapies were 20.9 for thrombolysis and 24.6 for EVT.

Conclusions—

The Melbourne MSU substantially reduced time to reperfusion therapies, with the greatest estimated disability avoidance driven by the more powerful impact of earlier EVT. These findings highlight the benefits of prehospital notification and direct triage to EVT centers with facilitated workflow on arrival by the MSU.

Advances in stroke medicine

In recent years, reperfusion therapies such as intravenous thrombolysis and endovascular thrombectomy for ischaemic stroke have dramatically reduced disability and revolutionised stroke management. Thrombolysis with alteplase is effective when administered to patients with potentially disabling stroke, who are not at high risk of bleeding, within 4.5 hours of the time the patient was last known to be well. Emerging evidence suggests that other thrombolytics such as tenecteplase may be even more effective. Treatment may be possible beyond 4.5 hours in patients selected using brain imaging. Endovascular thrombectomy (via angiography) effectively reduces risk of death or dependency in patients with large vessel occlusion (internal carotid, proximal middle cerebral and basilar arteries) if applied within 6 hours of the time they were last known to be well. Endovascular thrombectomy is also beneficial 6-24 hours from the last known well time in selected patients with favourable brain imaging. Thus, some patients with wake-up stroke are now treatable, and protocols for stroke need to include computed tomography (CT) perfusion scan and CT angiography as routine, in addition to the non-contrast CT brain scan. Optimised pre-hospital and emergency department systems (eg, code stroke response teams, pre-notification by ambulance, direct transport from triage to CT scanner) are essential to maximise the benefit of these strongly time-dependent therapies. Telemedicine is increasingly providing specialist guidance for these more complex treatment decisions in rural areas. Important developments in secondary stroke prevention include the use of direct oral anticoagulants or left atrial appendage occlusion for atrial fibrillation, and endovascular closure of patent foramen ovale.

Optimizing in-hospital triage for large vessel occlusion using a novel clinical scale (GAI2AA)

Objective

To identify a proximal anterior circulation occlusion for effectively administering immediate mechanical thrombectomy by developing a novel, simple diagnostic scale to predict the occlusion, to compare its validity with available scales, and to assess its utility.

Methods

To develop a novel clinical scale, we retrospectively analyzed a cohort of 429 patients with acute ischemic stroke from a single center. The novel scale GAI₂AA was applied to a prospective cohort of 259 patients from 3 stroke centers for external validation. The utility of the scale as an in-hospital triage was compared for the temporal factors of 158 patients with the occlusion.

Results

In a scale-developmental phase, those with a proximal anterior circulation occlusion had significantly more frequent signs of hemispheric symptoms, including gaze palsy, aphasia, inattention, arm paresis, and atrial fibrillation. The GAI₂AA scale was developed using consolidated hemispheric symptoms and was scored as follows: score = 2, arm paresis score = 1, and atrial fibrillation score = 1. A cutoff value ≥3 was optimal for the correlation between sensitivity (88%) and specificity (81%), with a C statistic of 0.90 (95% confidence interval 0.87–0.93). External validation indicated that discrimination was significantly better than or not different from that of available complex scales. Door-to-puncture time was significantly reduced (91 [82–111] vs 52 [32–75] minutes, p < 0.001).

Conclusion

The GAI₂AA scale showed high sensitivity and specificity when an optimal cutoff score was used and was useful as an in-hospital triage tool.

Ischaemic stroke

Stroke is the second highest cause of death globally and a leading cause of disability, with an increasing incidence in developing countries. Ischaemic stroke caused by arterial occlusion is responsible for the majority of strokes. Management focuses on rapid reperfusion with intravenous thrombolysis and endovascular thrombectomy, which both reduce disability but are time-critical. Accordingly, improving the system of care to reduce treatment delays is key to maximizing the benefits of reperfusion therapies. Intravenous thrombolysis reduces disability when administered within 4.5 h of the onset of stroke. Thrombolysis also benefits selected patients with evidence from perfusion imaging of salvageable brain tissue for up to 9 h and in patients who awake with stroke symptoms. Endovascular thrombectomy reduces disability in a broad group of patients with large vessel occlusion when performed within 6 h of stroke onset and in patients selected by perfusion imaging up to 24 h following stroke onset. Secondary prevention of ischaemic stroke shares many common elements with cardiovascular risk management in other fields, including blood pressure control, cholesterol management and antithrombotic medications. Other preventative interventions are tailored to the mechanism of stroke, such as anticoagulation for atrial fibrillation and carotid endarterectomy for severe symptomatic carotid artery stenosis.

Diagnostic accuracy of clinical tools for assessment of acute stroke: a systematic review

INTRODUCTION

Recanalisation therapy in acute ischaemic stroke is highly time-sensitive, and requires early identification of eligible patients to ensure better outcomes. Thus, a number of clinical assessment tools have been developed and this review examines their diagnostic capabilities.

METHODS

Diagnostic performance of currently available clinical tools for identification of acute ischaemic and haemorrhagic strokes and stroke mimicking conditions was reviewed. A systematic search of the literature published in 2015-2018 was conducted using PubMed, EMBASE, Scopus and The Cochrane Library. Prehospital and in-hospital studies with a minimum sample size of 300 patients reporting diagnostic accuracy were selected.

RESULTS

Twenty-five articles were included. Cortical signs (gaze deviation, aphasia and neglect) were shown to be significant indicators of large vessel occlusion (LVO). Sensitivity values for selecting subjects with LVO ranged from 23 to 99% whereas specificity was 24 to 97%. Clinical tools, such as FAST-ED, NIHSS, and RACE incorporating cortical signs as well as motor dysfunction demonstrated the best diagnostic accuracy. Tools for identification of stroke mimics showed sensitivity varying from 44 to 91%, and specificity of 27 to 98% with the best diagnostic performance demonstrated by FABS (90% sensitivity, 91% specificity). Hypertension and younger age predicted intracerebral haemorrhage whereas history of atrial fibrillation and diabetes were associated with ischaemia. There was a variation in approach used to establish the definitive diagnosis. Blinding of the index test assessment was not specified in about 50% of included studies.

CONCLUSIONS

A wide range of clinical assessment tools for selecting subjects with acute stroke has been developed in recent years. Assessment of both cortical and motor function using RACE, FAST-ED and NIHSS showed the best diagnostic accuracy values for selecting subjects with LVO. There were limited data on clinical tools that can be used to differentiate between acute ischaemia and haemorrhage. Diagnostic accuracy appeared to be modest for distinguishing between acute stroke and stroke mimics with optimal diagnostic performance demonstrated by the FABS tool. Further prehospital research is required to improve the diagnostic utility of clinical assessments with possible application of a two-step clinical assessment or involvement of simple brain imaging, such as transcranial ultrasonography.

Application of Strategic Transport Model and Google Maps to Develop Better Clot Retrieval Stroke Service

Background and purpose: Two hubs are designated to provide endovascular clot retrieval (ECR) for the State of Victoria, Australia. In an earlier study, Google Maps application programming interface (API) was used to perform modeling on the combination of hospitals optimizing for catchment in terms of current traveling time and road conditions. It is not known if these findings would remain the same if the modeling was performed with a large-scale transport demand model such as Victorian Integrated Transport Model (VITM). This model is developed by the Victorian State Government Transport has the capability to forecast travel demand into the future including future road conditions which is not possible with a Google Maps based applications. The aim of this study is to compare the travel time to potential ECR hubs using both VITM and the Google Maps API and model stability in the next 5 and 10 years.

Methods: The VITM was used to generate travel time from randomly generated addresses to four existing ECR capable hubs in Melbourne city, Australia (i.e., Royal Melbourne Hospital/RMH, Monash Medical Center/MMC, Alfred Hospital/ALF, and Austin Hospital/AUS) and the optimal service boundaries given a delivering time threshold are then determined.

Results: The strategic transport model and Google map methods were similar with the R² of 0.86 (peak and off peak) and the Nash-Sutcliffe model of efficiency being 0.83 (peak) and 0.76 (off-peak travel). Futures modeling using VITM found that this proportion decreases to 82% after 5 years and 80% after 10 years. The combination of RMH and ALF provides coverage for 74% of cases, 68% by 5 years, and 66% by 10 years. The combination of RMH and AUS provides coverage for 70% of cases in the base case, 65% at 5 years, and 63% by 10 years.

Discussion: The results from strategic transport model are similar to those from Google Maps. In this paper we illustrate how this method can be applied in designing and forecast stroke service model in different cities in Australia and around the world.

Prehospital stroke care, a narrative review

Stroke is a leading cause of disability in the United States and current treatment for stroke is limited to two modalities with well-defined time restraints. The prehospital setting is a significant and relatively easy setting for innovation in stroke care, as the most clinical decisions are made within the first several hours of symptom onset. In this review, we look at recent innovations in improving prehospital care for acute stroke including the conception of mobile stroke units, the ongoing development of stroke models for emergency providers, barriers to prehospital care, and the innovation of new telephone applications. Although there are notable improvements in acute stroke care, additional research is needed to further improve on current models and technologies.

The Speech Arm Vision Eyes (SAVE) scale predicts large vessel occlusion stroke as well as more complicated scales

INTRODUCTION

The Speech Arm Vision Eyes (SAVE) scale, a 4-item clinical scale emphasizing binary scoring and avoidance of nuanced examination distinctions, predicts LVOs with similar characteristics as more complex scales.

METHODS

Receiver operating characteristic analyses of the prospective STOPStroke study assessed the ability of the SAVE scale and other published scales to predict LVO. We identified scale thresholds with positive likelihood ratios with 95% confidence intervals of ≥5.0 or negative likelihood ratios with 95% confidence intervals of ≤0.5.

RESULTS

735patients were studied. LVO prevalence was 33%. Area under the curve was 0.79 for SAVE, 0.82 for FAST-ED, 0.80 for mNIHSS and NIHSS, and lower for all other scales. SAVE=4, EMSA=6, mNIHSS≥10, NIHSS≥16, and RACE≥8 had positive likelihood ratios with 95% confidence intervals ≥5.0. SAVE≥2, CPSS≥2, C-STAT≥1, EMSA≥4, FAST-ED≥3, G-FAST≥3, mNIHSS≥6, NIHSS≥9, PASS≥1, RACE≥2, VAN=1, and 3I-SS≥1 had negative likelihood ratios with 95% confidence intervals ≤0.5.

CONCLUSIONS

SAVE=4 performed similarly to more complex scales at predicting LVO. Other simplified scales did not have thresholds with positive likelihood ratios with 95% confidence intervals ≥5.0. Validation is need in a prehospital cohort of patients with suspected stroke.

Large Vessel Occlusion in Acute Stroke

Background and Purpose—

To date, no clinical score has become widely accepted as an eligible prehospital marker for large vessel occlusion (LVO) and the need of mechanical thrombectomy (MT) in ischemic stroke. On the basis of pathophysiological considerations, we propose that cortical symptoms such as aphasia and neglect are more sensitive indicators for LVO and MT than motor deficits.

Methods—

We, thus, retrospectively evaluated a consecutive cohort of 543 acute stroke patients including patients with ischemia in the posterior circulation, hemorrhagic stroke, transient ischemic attack, and stroke mimics to best represent the prehospital setting.

Results—

Cortical symptoms alone showed to be a reliable indicator for LVO (sensitivity: 0.91; specificity: 0.70) and MT (sensitivity: 0.90; specificity: 0.60) in acute stroke patients, whereas motor deficits showed a sensitivity of 0.85 for LVO (specificity: 0.53) and 0.87 for MT (specificity: 0.48).

Conclusions—

We propose that in the prehospital setting, the presence of cortical symptoms is a reliable indicator for LVO and its presence justifies transportation to an MT-capable center.