Field Assessment Stroke Triage For Emergency Destination Research Articles

Abstract WP78: Large Vessel Occlusion Triage and Routing Utilized for Long-Distance Stroke Transports by Emergency Medical Services (LVO TRUST EMS)

Introduction: Endovascular treatment (EVT) is the most effective therapy in acute ischemic stroke (AIS) with large vessel occlusion (LVO) but its practice is limited to comprehensive stroke centers (CSC). Previous studies have suggested that trained Emergency Medical Services (EMS) professionals can successfully detect LVO cases using a validated screening tool. For these cases, direct transfer to CSC bypassing community hospitals could lead to better outcomes. Methods: This is a retrospective cohort study from 01/01/2018-12/31/2022 of patients with suspected stroke transported by EMS providers from 14 community agencies (primarily fire paramedics) in Southeastern Massachusetts (EMS Region V). When stroke was suspected, EMS providers applied the Field Assessment Stroke Triage for Emergency Destination (FAST-ED) score to assess severity. Bypass of local community hospitals for direct transport to CSC was generally considered for patients with FAST-ED ≥4 and approval of the Region V EMS Medical Director, with the goal of early intervention for severe strokes. In addition to standard education on the use of the FAST-ED score, the EMS agencies received annual aggregate performance feedback and individual case feedback (when requested) from the CSC. Data were collected from the Electronic Health Record (EHR) on demographics, comorbidities, final diagnoses, FAST-ED scores, NIHSS and acute treatments. Descriptive statistics were performed to describe the accuracy of diagnosis and rates of treatment. Results: Among 166 triaged patients to go directly to CSC, 57.6% (95/166) were diagnosed with AIS, and 61.1% (58/95) of them were found to have LVO. There was a higher proportion of AIS or intracranial hemorrhage (ICH) in cases with higher FAST-ED scores. Only 23.4% (39/166) of the cases were diagnosed with stroke mimics, primarily related to lower FAST-ED scores. In total, 36.9% of patients with AIS received EVT: thrombectomy with standard window tPA (21.1%) or late presenter tPA (LKW ≥ 4.5 h, 1.1%), and without tPA (14.7%). Conclusions: A diverse group of community-based EMS services in Southeastern Massachusetts using a prehospital tool can identify patients with severe stroke, i.e. AIS due to LVO or ICH, with acceptable diagnostic accuracy.

The diagnostic value of the field assessment stroke triage as an emergency destination tool in identifying the obstruction of large cerebral vessels: a systematic review and meta-analysis

Objective: In this study, we investigate the diagnostic value of the field assessment stroke triage for emergency destination (FAST-ED) tool in the diagnosis of large vessels occlusion (LVO) in a systematic review and meta-analysis.
 Methods: We conducted a search in Medline (PubMed), Embase, Scopus, and Web of Science databases until the 21st of September 2022, as well as a manual search in Google and Google scholar to find related articles. Studies of diagnostic value in adult population were included. Screening, data collection and quality control of articles were done by two independent researchers. The data were entered and analyzed in STATA 17.0 statistical program.
 Results: The data from 30 articles were entered. The best cut-off points for FAST-ED were 3 or 4. The sensitivity and specificity of FAST-ED at cut-off points 3 were 0.77 (95% CI:0.73,0.80) and 0.76 (95% CI:0.72,0.80), respectively. These values ​​for cut-off point 4 were 0.72 (95% CI:0.65,0.78) and 0.79 (95% CI:0.75,0.82), respectively. Meta-regression showed that the sensitivity and specificity of FAST-ED performed by a neurologist was more accurate compared to emergency physician (P for sensitivity=0.01; P for specificity<0.001) and emergency medical technicians (P for sensitivity=0.03; P for specificity<0.001). Finally, it was found that the sensitivity of FAST-ED performed by the emergency physician and the emergency medical technician has no statistically significant difference (P=0.76). However, the specificity of FAST-ED reported by the emergency physician is significantly higher (P<0.001). The false negative rate of this tool at cut-off points 3 and 4 is 22.5% and 28.8%, respectively. 
 Conclusion: Although FAST-ED has an acceptable sensitivity in identifying LVO, its false negative rate varies between 22.5% and 28.8%. A percentage this high is unacceptable for a screening tool to aid in the diagnosis of strokes considering it has a high rate or morbidity and mortality. Therefore, it is recommended to use another diagnostic tool for the stroke screening.

FAST-ED scale for prehospital triage of large vessel occlusion: results in the field.

Acute ischemic stroke (AIS) is an extremely time-sensitive condition. The field triage of stroke patients should consider a careful balance between the best destination for the timely delivery of intravenous and/or endovascular reperfusion therapies. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale has been shown to have an accuracy comparable to that of the National Institutes of Health Stroke Scale (NIHSS). However, it has not been tested in the field. To evaluate the accuracy of the FAST-ED scale in the detection of AIS due to large vessel occlusion (LVO) in the prehospital setting. A cross-sectional study of consecutive prospective data collected from February 2017 to May 2019 in the city of Porto Alegre, state of Rio Grande do Sul, Southern Brazil, correlating the prehospital FAST-ED scale scores with the hospital diagnosis of LVO. Area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. In total, 74 patients were included in the analysis. As compared with the diagnosis of LVO upon hospital discharge, the prehospital FAST-ED scale applied by paramedics had a sensitivity of 80%, a specificity of 47.7%, a PPV of 51.1%, an NPV of 77.8%, and an AUC of 0.68 (95% confidence interval [95%CI]: 0.55-0.80). Among the patients with a final diagnosis of AIS, the accuracy was higher, with an AUC of 0.75 (95%CI: 0.60-0.89), a sensitivity of 80%, a specificity of 60%, a PPV of 80%, and an NPV of 60%. In the present study, the FAST-ED scale, which was applied by paramedics in the field, demonstrated moderate accuracy but high sensitivity and NPV, which are essential attributes for a triage scale. While larger studies are still needed, these findings further support the use of the FAST-ED in stroke triage.

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

IntroductionWe 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...

Comparison of large vessel occlusion scales using prehospital patient reports.

Prehospital identification of large vessel occlusion (LVO) holds significant potential to decrease the onset-to-treatment time. Several prehospital scales have been developed to identify LVO but data on their comparison has been limited. The aim of this study was to review the currently available prehospital LVO scales and compare their performance using prehospital data. All patients transported by ambulance using stroke code on a six-month period were enrolled into the study. The prehospital patient reports were retrospectively evaluated by two investigators using sixteen LVO scales identified by literature search and expert opinion. After the evaluation, the computed tomography angiography results were reviewed by a neuroradiologist to confirm or exclude LVO. Sixteen different LVO scales met the predetermined study criteria and were selected for further comparison. Using them, a total of 610 evaluations were registered. The sensitivity of the scales varied between 8%-73%, specificity between 71%-97% and overall accuracy between 71%-87%. The areas under curve (AUC) varied between 0.61-0.80 for the whole scale range and 0.53%-0.74 for the scales' binary cut-offs. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) was the only scale with AUC>0.8. Regarding scales' binary cut-offs, The FAST-ED (0.70), Gaze - Face Arm Speech Time (G-FAST) (0.74) and Emergency Medical Stroke Assessment (EMSA) (0.72) were the only scales with AUC>0.7. In a comparison of 16 different LVO scales, the FAST-ED, G-FAST and EMSA achieved the highest overall performance.

Validation of field assessment stroke triage for emergency destination for prehospital use in a rural EMS system.

Field Assessment Stroke Triage for Emergency Destination (FAST-ED) is a simple and accurate prehospital stroke severity scale that has been shown to have comparable accuracy to the gold standard National Institutes of Health Stroke Scale (NIHSS) but requires further field validation for use by emergency medical services (EMS), particularly in rural systems. FAST-ED scores ≥4 are considered high probability for large vessel occlusion (LVO) strokes, while scores <4 are low to moderate probability for LVO. The objective of this study was to assess inter-rater reliability of the EMS FAST-ED (EMS) score to the emergency department FAST-ED (ED-MD) scores. EMS calculated FAST-ED scores prior to transport to the emergency department (ED) on patients with a positive prehospital stroke screen. EDMD calculated FAST-ED scores for the same patients upon arrival to the ED. Interrater reliability and test characteristics were calculated. A total of 95 patients were included in this study and 14 were subsequently diagnosed with an LVO. EMS assigned 34 patients (35.8%) a FAST-ED score of ≥4. EDMD assigned 25 patients (26.3%) a FAST-ED score of ≥4. Using the clinical cut-points of FAST-ED scores <4 and ≥ 4, a linearly weighted Cohen's kappa coefficient showed moderate interrater reliability when comparing EMS and EDMD scores (kw 0.44, 95% CI 0.25-0.63). At ≥4, EMS FAST-ED scores had a sensitivity 0.48, specificity 0.75, PPV 0.62, NPV 0.62 for predicting an LVO, while EDMD FAST-ED scores had a sensitivity 0.36, specificity 0.82, PPV 0.64, NPV 0.60. Comparable receiver operator curve area under the curve values were obtained. EMS and EDMD FAST-ED scores were moderately comparable in a rural EMS system. Similar NPVs compared to EDMD suggest the use of FAST-ED as an appropriate screening tool for EMS to predict the probability of LVO in the prehospital setting and make destination determinations regarding primary transport to a thrombectomy-capable stroke center.

Prehospital Evaluation of the FAST-ED as a Secondary Stroke Screen to Identify Large Vessel Occlusion Strokes

Introduction: The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) was developed to identify Large Vessel Occlusion Strokes (LVOS) presenting out of hospital, although there is limited prospective research validating its use in this setting. This study evaluated the test characteristics of the FAST-ED to identify LVOS when used as a secondary stroke screen in the prehospital environment. Secondary analysis compared the performance of the CPSS and the FAST-ED in identifying an LVOS. Methods: This prospective, observational study was conducted from April 2018 to December 2019 in a municipal EMS system with all ALS ambulance response. The FAST-ED was implemented as a secondary screening tool for emergent stroke patients who had at least one positive Cincinnati Prehospital Stroke Screen (CPSS) item. CPSS and FAST-ED scores were extracted from prehospital electronic care reports, while the presence of LVOS was extracted from hospital records. Results: A total 1,359 patients were enrolled; 55.3% female, 47.5% white, with a mean age of 69.4 (SD 15.8). In this cohort, 11.3% of patients experienced an LVOS. The mean FAST-ED for a patient experiencing an LVOS was 5.33 (95%CI 4.97–5.69) compared to 3.06 (95%CI 2.95–3.12) (p < 0.001). A score of greater or equal to 4 yielded the highest combination of sensitivity (77.78%) and specificity (65.34%) with positive likelihood ratio 2.24 (95% CI 2.00–2.52) and negative likelihood ratio 0.34 (95% CI 0.25–0.46). Area under the ROC curve was 0.77 (95%CI 0.73, 0.81). A CPSS with all three items positive demonstrated a sensitivity of 73.20% and 69.57% specificity, with an ROC area of 0.73 (95% CI 0.70–0.77). When comparing a FAST-ED ≥4 to a CPSS of all positive items, there was no significant difference in sensitivity (p > 0.05), and the FAST-ED had a significantly lower specificity than the CPSS (p < 0.005). Conclusion: As stroke care advances, EMS agencies must consider their destination triage needs. This study suggests agencies must consider the use of single versus secondary scales, and to determine the ideal sensitivity and specificity for their system.

Prehospital identification of large vessel occlusion using the FAST-ED score.

The prehospital identification of stroke patients with large vessel occlusion (LVO) enables appropriate hospital selection and reduces the onset-to-treatment time. The aim of this study was to investigate whether the Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale could be reconstructed from existing prehospital patient reports and to compare its performance with neurologist's clinical judgement using the same prehospital data. All patients transported by ambulance using stroke code on a six-month period were registered for the study. The prehospital patient reports were retrospectively evaluated using the FAST-ED scale by two investigators. The performance of FAST-ED score (≥4 points) in LVO identification was compared to neurologist's clinical judgement ('LVO or not'). The presence of LVO was verified using computed tomography angiography imaging. A total of 610 FAST-ED scores were obtained. The FAST-ED had a sensitivity of 57.8%, specificity of 87.2%, positive predictive value (PPV) of 37.3%, negative predictive value (NPV) of 93.4% and area under curve (AUC) of 0.724. Interclass correlation coefficient for both raters over the entire range of FAST-ED was 0.92 (0.88-0.94). The neurologist's clinical judgement raised sensitivity to 79.4%, NPV to 97.1% and PPV to 45.0% with an AUC of 0.837 (p<.05). The existing patient report data could be feasibly used to reconstruct FAST-ED scores to identify LVO. The binary FAST-ED score had a moderate sensitivity and good specificity for prehospital LVO identification. However, the FAST-ED was surpassed by neurologist's clinical judgement which further increased the sensitivity of identification.

Reliability of Field Assessment Stroke Triage for Emergency Destination Scale Use by Paramedics: Mobile Stroke Unit First-Year Experience.

Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale is a helpful tool to triage patients with stroke in the field. However, data on its reliability in the prehospital setting are lacking. We aim to test the reliability of FAST-ED scale when used by paramedics in a mobile stroke unit covering a metropolitan area. As part of standard operating mobile stroke unit procedures, paramedics initially evaluated patients. If the event characterized a stroke alert, the FAST-ED score was determined by the paramedic upon patient contact (in-person) and then independently by a vascular neurologist (VN) immediately after paramedic evaluation (remotely/telemedicine). This allowed testing of the interrater agreement of the FAST-ED scoring performance between on-site prehospital providers and remotely located VN. Of a total of 238 patients transported in the first 15 months of the mobile stroke unit’s activity, 173 were included in this study. Median age was 63 (interquartile range, 55.5–75) years and 52.6% were females. A final diagnosis of ischemic stroke was made in 71 (41%), transient ischemic attack in 26 (15%), intracranial hemorrhage in 15 (9%), whereas 61 (35%) patients were stroke mimics. The FAST-ED scores matched perfectly among paramedics and VN in 97 (56%) instances, while there was 0 to 1-point difference in 158 (91.3%), 0 to 2-point difference in 171 (98.8%), and 3 or more point difference in 2 (1.1%) patients. The intraclass correlation between VN and paramedic FAST-ED scores showed excellent reliability, intraclass correlation coefficient 0.94 (95% CI, 0.92–0.96; P<0.001). When VN recorded FAST-ED score ≥3, paramedics also scored FAST-ED≥3 in majority of instances (63/71 patients; 87.5%). A large vessel occlusion was identified in 16 (9.2%) patients; 13 occlusions were identified with a FAST-ED≥3 while 3 were missed. All of the latter patients had National Institutes of Health Stroke Scale score ≤5. We demonstrate excellent reliability of FAST-ED scale performed by paramedics when compared with VN, indicating that it can be accurately performed by paramedics in the prehospital setting.

Inter-Rater Reliability of the FAST-ED in the Out-of-Hospital Setting

Introduction: Patients experiencing a large vessel occlusion stroke (LVOS) may require endovascular-capable centers and benefit from direct transport to such facilities, creating a need for an accurate prehospital assessment. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) is a secondary scale to identify LVOS. Currently, there is limited prospective evidence validating the use of the FAST-ED in the prehospital environment. This study aimed to evaluate the inter-rater reliability of the FAST-ED between patient care providers in the prehospital setting. Methods: This prospective study was conducted between 4/1/2018 and 7/1/2018 in a single municipal EMS agency that staffs two providers per ambulance with at least one being a paramedic. Patients were included based on paramedic impression that the patient was both having a stroke and greater than 18 years old. Each provider independently performed and documented a FAST-ED assessment on eligible patients. Data analysis consisted of performing inter-rater reliability using Cohen’s Kappa on the FAST-ED score between primary and secondary providers. The FAST-ED was analyzed on an item level, an aggregate level (cumulative of all items), and using the defined cut point of ≥4. A sub-analysis determined if inter-rater reliability changed across provider certification. Results: There were 231 patients included in this analysis with an average age of 68.5 years and 135 (58.4%) female. Inter-rater reliability varied across individual items in the scale from 90.1% agreement to 82.5%. When analyzing inter-rater reliability of the aggregate FAST-ED score, the scale demonstrated 70.1% agreement (Kappa 0.66), considered substantial agreement. FAST-ED scores were analyzed using a cut point of ≥4. When using this cut point, there was 92.2% (Kappa 0.81) agreement between primary and secondary caregiver, demonstrating almost perfect agreement. Agreement was substantial across provider certifications including paramedics and EMTS. Conclusion: This study demonstrated high inter-rater reliability of the FAST-ED scale when performed in the prehospital setting on patients suspected of having a stroke. There were minimal differences in reliability based on provider certification, and item level analysis indicated substantial inter-rater reliability.

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.

The Effect of a County Prehospital FAST-ED Initiative on Endovascular Treatment Times

BackgroundAcute stroke outcomes depend on timely reperfusion. In 3/2017, local EMS agencies implemented a prehospital triage algorithm with hospital bypass and field activation of the neurointerventional team using the Field Assessment Stroke Triage for Emergency Destination (FAST-ED). A score ≥4 bypasses to a comprehensive stroke center (CSC) and a score ≥6 also has the interventional team field activated off-hours. AimWe analyzed effects of this initiative on volume, acute stroke transfers, treatment times, and outcomes and determined the tool's ability to predict large vessel occlusion. MethodsStroke cases brought to our center by EMS during 3/2016-2/2018 were analyzed, which included one year before and after FAST-ED implementation. Treatment times were compared on- vs. off-hours and to those with field activation. ResultsOf 1153 patients, 761 (67%) were coded as stroke and 235 (20%) underwent reperfusion. Age, sex, race/ethnicity, stroke severity, length of stay, door-to-needle, and 90-d mRS were comparable between periods. Scale compliance was 85%. Concordance rate of ±1 between EMS and calculated score was 53%. Compared to the previous year, door-to-puncture (DTP) improved by 17 min (p < 0.01) overall, 25 min (p < 0.001) off-hours, and 33 min (p < 0.05) with field activation. A cutoff of 4 vs. 6 would have led to 140% increase in field activations but only 36% increase in procedures. ConclusionsThis prehospital initiative led to faster DTP by up to 33 min. The highest impact was off-hours with field activation. Only 1/3 of activations led to endovascular treatment. FAST-ED≥6 appears to be appropriate for field activation.

Can Prehospital Personnel Accurately Triage Patients for Large Vessel Occlusion Strokes?

The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) score was developed in the hospital setting to be used in the prehospital setting. It has been shown to have higher predictive value than comparable stroke scales, including the National Institutes of Health Stroke Scale, for identifying large vessel occlusion strokes. We sought to determine whether prehospital FAST-ED scores are comparable with FAST-ED scores determined by emergency physicians. Emergency Medical Services (EMS) personnel were trained to calculate a FAST-ED score for any patient suspected of having a stroke in the field. When the patient arrived at our ED, an emergency physician generated a FAST-ED score. One hundred and thirty-five patients were studied and large vessel occlusions were detected in 23.7%. There was no significant difference between median FAST-ED scores from EMS personnel (3; interquartile range [IQR] 1-5) and emergency physician (2; IQR 1-6). The difference between paired scores was not significantly different from 0 (median of paired differences was 0). In addition, prehospital FAST-ED scores were significantly and positively correlated with physician FAST-ED scores (r2=0.26). Comparable receiver operator curve area under the curve values were obtained for EMS FAST-ED (0.727; 95% confidence interval [CI] 0.638-0.816) and ED FAST-ED (0.769; 95% CI 0.669-0.868). The findings validate that prehospital FAST-ED scores are comparable in predictive value to FAST-ED scores calculated in the ED for prediction of large vessel occlusion strokes.

Vision, Aphasia, Neglect Assessment for Large Vessel Occlusion Stroke

Background and PurposeVision, Aphasia, Neglect (VAN) is a large vessel occlusion (LVO) screening tool that was initially tested in a small study where emergency department (ED) nurses were trained to perform VAN assessment on stroke code patients. We aimed to validate the VAN assessment in a larger inpatient dataset. MethodsWe utilized a large dataset and used National Institute of Health Stroke Scale (NIHSS) performed by physicians to extrapolate VAN. VAN was compared to NIHSS greater than or equal to 6 and established prehospital LVO screening tools including Rapid Arterial Occlusion Evaluation scale (RACE), Field Assessment Stroke Triage for Emergency Destination (FAST-ED), and Cincinnati Pre-hospital Stroke Scale (CPSS). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and area under receiver operating characteristics curve was calculated to estimate the predictive value of LVO. ResultsVAN was comparable in sensitivity (79% versus 80%) and NPV (88% versus 87%) to NIHSS greater than or equal to 6. It was superior in specificity (69% versus 57%), PPV (53% versus 46%) and accuracy to NIHSS greater than or equal to 6 (72% versus 64%) with significant receiver operating curve (.74 versus .69, P = .02).VAN also had comparable area under the curve when compared to RACE, FAST-ED, and CPSS however slightly lower accuracy (69%-73%) compared to RACE (76%), FAST-ED (77%), and CPSS (75%). VAN had the highest NPV among all screening assessments (88%). ConclusionsVAN is a simple screening tool that can identify LVOs with adequate accuracy in hospital setting. Future studies need to be conducted in prehospital setting to validate its utility to detect LVOs in the field.

Mechanical Revascularization in the Era of the Field Assessment Stroke Triage for Emergency Destination (FAST-ED): A Retrospective Cohort Assessment in a Community Stroke Practice

BackgroundEndovascular mechanical revascularization has become the mainstay acute stroke management secondary to emergent large vessel occlusions. In patients who can benefit from mechanical revascularization, the ability to intervene in a timely manner directly correlates with improved outcomes. The field assessment for stroke triage (FAST-ED) prehospital triage tool, is one of many stroke severity scales designed to decrease time to diagnosis in the field and optimize patient triage to comprehensive stroke centers. It is however unclear what impact if any, this tool has on time to activation of hospital stroke intervention teams. We set out to assess the impact of the implementation of the FAST-ED triage tool on the activation of the stroke intervention team in a community stroke treatment practice. MethodsWe retrospectively reviewed institutional records for consecutive admissions with reported stroke alerts between March 2017 and September 2018, and selected patients who presented via Emergency Medical Services (EMS). The association between FAST-ED scores and impact on time to revascularization as well as the association between FAST-ED scores and the presence of emergent large vessel occlusion were analyzed. ResultsThere was a statistically significant improvement in interventional team activation times in favor of the FAST-ED cohort, (P < .05). ConclusionsFAST-ED implementation demonstrates a statistically significant improvement on stroke team activation times for patients who are candidates for mechanical revascularization. Larger cohort analysis is needed to fully evaluate the magnitude of this effect.

Effect of Known Atrial Fibrillation and Anticoagulation Status on the Prehospital Identification of Large Vessel Occlusion

Introduction: The Cincinnati Prehospital Stroke Severity scale (C-STAT), Los Angeles Motor Scale (LAMS), Rapid Arterial Occlusion Evaluation (RACE) score, and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scales were designed to aid emergency responder identification of patients with stroke related to large vessel occlusion (LVO). We hypothesized that the addition of a known history of atrial fibrillation (AF) without anticoagulation to currently used scales would improve LVO detection. Methods: Medical records of patients admitted to a Comprehensive Stroke Center with acute ischemic stroke in 2014-2015 were reviewed. LVO identification using the C-STAT, LAMS, RACE, and FAST-ED scores and the AF variable were compared using univariable analyses. The areas under the receiver operating curves (AUCs) were then compared for each score, the AF variable, and each score with the addition of the AF variable. Results: The sample included 233 patients without and 188 patients with an LVO. A history of known AF, history of AF with no anticoagulation, and the C-STAT, LAMS, RACE, and FAST-ED scores were each associated with LVO in univariable analyses. The AUCs for C-STAT, LAMS, RACE, and FAST-ED were similar. The addition of the known AF and no anticoagulation variable did not appreciably change these AUCs. Conclusion: Although known AF with no anticoagulation was associated with LVO in patients with acute ischemic stroke, this historic feature did not improve the accuracy of existing LVO detection scales.

Abstract No. 540 Mechanical thrombectomy for emergent large-vessel occlusions (ELVO) in the era of the Field Assessment Stroke Triage for Emergency Destination (FAST-ED): a retrospective cohort assessment at a comprehensive stroke center

The FAST-ED is a verified pre-hospital screening tool for patients suspected of having an emergent large vessel occlusion (ELVO). It allows for early triaging of patients to comprehensive stroke centers for emergent comprehensive stroke treatment. We set out to study the effect of this pre-hospital triaging tool at a single center comprehensive stroke center. Institutional records of pre-hospital stroke alerts and FAST-ED scores were queried over a 17-month period. FAST-ED data was acquired from a single regional Fire and Rescue Team as implementation of the FAST-ED scoring metric was non-uniform across the regional emergency medical services (EMS). Demographic and clinical data was assessed including admission National Institute of Health Stroke Scale (NIHSS), incidence of mechanical thrombectomy, length of hospitalization as well as treatment metrics including time to catheterization. Between January 2017 and May 2018, 432 stroke alerts were activated of which 251 were generated by EMS, and 164 (65.3%) had documented FAST-ED scores. Among total pre-hospital stroke alerts, age distribution was 69.7 years±15 (mean±SD), and female predominance was 50.2%. In the 17 months, 28 patients received mechanical thrombectomy, and 21.5% received rT-PA (54 patients). In our analysis, overall median (IQR) FAST-ED and NIHSS scores were 3 (4) and 9 (16) respectively. Interestingly 95% of mechanical thrombectomies were performed on patients with FAST ED scores ≥ 4, and 96.4% on patients with NIHSS ≥ 5. The FAST-ED pre-hospital scoring metric is a useful tool as an adjunct to the NIHSS in the diagnosis of emergent large vessel occlusion. In the right setting it can be useful in optimizing treatment paradigms and improve time to treatment in these patients.

Abstract 33: FAST-ED Based Pre-Hospital Stroke Triage System Improves Endovascular Treatment Times, Especially off Hours

Introduction: Acute stroke outcomes depend on timely reperfusion. In March 2017, the Fire Officers Association of Miami-Dade (FOAMD) implemented the Field Assessment Stroke Triage for Emergency Destination (FAST-ED) scale. Those with a score ≥ 4 bypass other centers for a comprehensive stroke center (CSC) and those with a score ≥ 6 also have the interventional team activated from the field. We analyzed the impact of this initiative on volume, treatment times, outcomes, and distance traveled from scene. Methods: All stroke cases brought to Baptist Hospital of Miami by FOAMD during March 2016 through February 2018 were analyzed, which included a year before and after FAST-ED implementation. Treatment times were compared on vs. off hours and to those with a FAST-ED score ≥6. We used the FAST-ED score documented on the EMS run sheet and a calculated score based on the initial NIHSS. Results: A total of 1153 patients met criteria. Of these, 761 (67%) were coded as stroke (ischemic, hemorrhagic, or TIA), and 235 (20%) underwent reperfusion treatments. Age, sex, race/ethnicity, initial NIHSS, distance traveled, length of stay, door to needle time, and 90 day mRS were comparable between periods (Table). Scale compliance was 85%. Concordance rate of ±1 point between FOAMD and calculated score was 53%. Compared to the previous year, door to groin times (DTG) improved by 17 min (p&lt;0.01) overall, by 25 min (26%) (p&lt;0.001) off-hours only, and by 33 min (31%) (p&lt;0.05) off-hours and calculated FAST-ED ≥ 6. Discussion: The FAST-ED initiative led to faster DTG times. The highest impact is for off-hours with field activation. Only 1 out of 3 activations led to endovascular treatment.

Abstract WP288: Impact of Prehospital LVO Tools on the Delay of Care and Redistribution of Patients between Primary and Comprehensive Stroke Centers

Introduction: Several tools have been developed aimed at predicting large vessel occlusion (LVO) in the prehospital setting. If these tools are used to bypass Alteplase-but-not-thrombectomy-capable hospitals, this would speed the care for some patients, delay it for others, and unnecessarily redistribute some patients between hospitals. Methods: We examined a hypothetical scenario of 1,000 patients evaluated by EMS for possible stroke. We used data published by RACE (Rapid Arterial oCclusion Evaluation) that included 357 patients to calculate the rates of the different stroke subtypes. Ischemic stroke represented 67.2% of patients, hemorrhagic stroke 14.6%, transient ischemic attack 5.6%, and stroke mimic 12.6%. We applied the following assumptions: rate of LVO as 20% of total ischemic stroke, all patients evaluated by EMS within 3 hours from their last known well time with a rate of tPA utilization is 50%, endovascular-capable hospital is further away, similar door-to-needle (DTN) time in all hospitals, delay in DTN in false positive patients, and delay in door-to-groin time (DTG) in false negative patients. Seven tools were studied using published values for sensitivity and specificity. Results: Using no tools would lead to evaluation of all patients at the nearer hospital first, leading to delay in DTG of all 134 LVO patients, however no delay in DTN. Comparing the various tools, DTN delay would be highest with Cincinnati Prehospital Stroke Severity Scale (CPSSS; n=175) and least with 3-item stroke scale (3I-SS; n=23). DTG delay would be highest with Prehospital Acute Stroke Severity (PASS) and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) (n=52 for both) and least with RACE (n=20). Redistribution of patients would be highest with CPSSS and lowest with 3I-SS (reduction in patient volume to non-thrombectomy capable hospital 63% and 16% respectively and increase in volume for the thrombectomy-capable hospital by 371% and 19% respectively). Conclusion: Current tools have a very wide variation in performance. Although some tools would likely reduce the delay in DTG time for most (but not all) LVO patients, they risk delaying care for other patients and may cause an unnecessary redistribution of patients between hospitals.

Abstract WP293: A Prospective Validation of Stroke Network of Wisconsin (snow) Scale to Predict Large Vessel Occlusion (lvo) and Comparison With Other Stroke Scales

Background: Prior retrospective analysis confirmed that the Stroke Network of Wisconsin (SNOW) scale was highly predictive of large vessel occlusion (LVO) in patients with Acute Ischemic Stroke (AIS). In this study, we prospectively validated the SNOW scale for the identification of LVO. We also compared its accuracy to other stroke scales retrospectively applied to the same dataset. Methods: The SNOW scale consists of 3 exam elements: expressive aphasia/Speaking difficulty (S), neglect (N) and Ocular deviation (O). The scale is positive if any one of these items is present. We prospectively evaluated all acute ischemic stroke (AIS) patients who presented within 24 hours after onset at Aurora St. Luke’s Medical Center between July 2017-February 2018 and calculated the SNOW score. We retrospectively calculated Rapid Arterial Occlusion Evaluation (RACE), the Field Assessment Stroke Triage for Emergency Destination (FAST-ED), the Vision Aphasia and Neglect Scale (VAN), the Cincinnati Prehospital Stroke Severity (CPSS), the Los Angeles Motor Scale (LAMS), the Prehospital Acute Stroke Severity Scale (PASS) for all patients. The predictive performance of all scales and National Institute of Health Stroke Scale (NIHSS) cut offs ≥6 were determined and compared. LVO was defined by total occlusions involving the intracranial internal carotid artery, middle cerebral artery (M1), or basilar arteries Results: Among 344 AIS patients, 283 (82%) had vascular imaging and were included in the analysis. LVO was detected in 43 (15%). Positive SNOW scale showed: sensitivity = 0.84, specificity = 0.63, positive predictive value = 0.29, negative predictive value= 0.96, and area under the curve =0.74. SNOW scale had comparable accuracy to predict LVO as other scales and NIHSS cut offs ≥6. If LVO includes M2, positive SNOW had sensitivity of 0.85, specificity of 0.70, positive predictive value of 0.49, negative predictive value of 0.93 and area under the curve of 0.77. SNOW had the highest sensitivity but lowest specificity among other scales. Conclusion: The SNOW scale is a simple and accurate tool to help identify AIS due to LVO, and it compares favorably to the other scales evaluated. A prospective validation study of the SNOW scale in the prehospital setting is underway. .