E-057 Prospective prehospital evaluation of VAN and RACE large vessel occlusion prediction instruments on a mobile stroke unit

Introduction: FAST-ED scale is a helpful tool to triage stroke patients in the field. However, data on the accuracy of the scale in the pre-hospital setting is lacking. We aim to validate the use of FAST-ED by paramedics in a mobile stroke unit (MSU) covering a metropolis. Methods: As part of standard operating MSU procedures, paramedics clinically evaluated patients. If the event characterized a stroke alert, the FAST-ED score was determined by the paramedic (in-person) upon patient contact, and independently by a vascular neurologist (telemedicine) immediately after the paramedic evaluation. An MSU nurse determined the NIHSS. This will allow testing of the inter-rater agreement of the FAST-ED scoring performance between on-site pre-hospital providers and remotely located vascular neurologists. Results: In the first 13 months of the MSU’s activity 193 stroke-alert patients were evaluated. 103 (53%) patients had a final diagnosis of stroke/TIA (75/28, respectively), 21 (11%) intracranial hemorrhage, and 69 (36%) were considered stroke mimics. 28 (14%) patients received intravenous alteplase. In the first 48 patients, FAST-ED was only scored by the paramedic and in 145 patients by both the physician and paramedic. FAST-ED scores matched perfectly amongst paramedics and physicians in 77 (53%) instances, while there was only 1-point difference in 51 (35%), 2-point difference in 10 (6%) and 3-point difference in two. Correlation between physician and paramedic FAST-ED scores was highly positive (rho 0.898; 2-sided p<0.001), as well as the correlation between physicians FAST-ED score and NIHSS (rho 0.853; 2-sided p<0.001). When the physician recorded FAST-ED score≥3 (n=62), the paramedics also scored FAST-ED≥3 in the vast majority of instances (n=55; 89%). After hospital arrival, cerebrovascular imaging was deemed necessary and performed in 144 patients within 24 hours of arrival. A visible large vessel occlusion was identified in 30 patients; 18 occlusions were identified with a FAST-ED≥3 while 12 were missed (10/12 had NIHSS≤5). Conclusion: The correlation of the FAST-ED scoring between vascular neurologists and paramedics was highly positive, indicating that FAST-ED is accurately and reliably utilized by paramedics in the pre-hospital setting.

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The Neurological Examination Improves Cranial Accelerometry Large Vessel Occlusion Prediction Accuracy

Neurocritical Care ◽

10.1007/s12028-020-01144-6 ◽

2020 ◽

Author(s):

Kevin J. Keenan ◽

Paul A. Lovoi ◽

Wade S. Smith

Keyword(s):

Neurological Examination ◽

Prediction Accuracy ◽

Large Vessel ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Occlusion Prediction

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Abstract TMP63: Simplified SAVE Large Vessel Occlusion Prediction Scale Performs Similarly to More Complex Scales

Stroke ◽

10.1161/str.49.suppl_1.tmp63 ◽

2018 ◽

Vol 49 (Suppl_1) ◽

Author(s):

Kevin J Keenan ◽

Wade S Smith

Keyword(s):

Large Vessel ◽

Large Vessel Occlusion ◽

Vessel Occlusion ◽

Occlusion Prediction

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Abstract 1122‐000126: Mobile Stroke Unit Process Metrics in Large Vessel Occlusion Stroke Patients: BEST‐MSU Substudy

Stroke: Vascular and Interventional Neurology ◽

10.1161/svin.01.suppl_1.000126 ◽

2021 ◽

Vol 1 (S1) ◽

Author(s):

Alexandra L Czap ◽

Anne W Alexandrov ◽

May Nour ◽

Noopur Singh ◽

Mengxi Wang ◽

...

Keyword(s):

Stroke Unit ◽

Large Vessel ◽

Categorical Variables ◽

Continuous Variables ◽

Stroke Patients ◽

Vessel Occlusion ◽

Stroke Treatment ◽

Symptomatic Intracerebral Hemorrhage ◽

Mobile Stroke Unit ◽

Process Metrics

Introduction : Mobile Stroke Units (MSUs) speed thrombolytic treatment for acute ischemic stroke and improve clinical outcomes compared to standard management by Emergency Medical Services (EMS). However, MSU process metrics in the subset of patients with large vessel occlusions (LVOs) having endovascular thrombectomy (EVT) have yet to be optimized. Methods : A pre‐specified Benefits of Stroke Treatment Using a Mobile Stroke Unit (BEST‐MSU) substudy of tPA‐eligible stroke patients with imaging evident LVOs was conducted. The primary outcome was process metrics related to treatment times from stroke onset and first medical alert. Safety outcomes included rates of symptomatic intracerebral hemorrhage and procedural complications. Groups were compared using Chi‐square or Fisher’s exact tests for categorical variables, and Wilcoxon rank‐sum tests for continuous variables. Results : A total of 295 patients were included, 169 in the MSU group and 126 in the EMS group. Baseline characteristics were comparable between the groups, with the exception of baseline NIHSS (MSU mean 19.0 [IQR 13.0,23.0] vs EMS 16.0 [11.0, 20.0], p = 0.003). 92% of MSU and 87% of EMS LVO patients received tPA, and 78% and 85% went on to have EVT. Process metrics are detailed in Table 1. MSU LVO patients had faster tPA bolus from 911‐alert (MSU 45.0 minutes [40.0, 53.5] vs EMS 76.0 [64.0, 87.8], p<0.001), however the two groups had similar alert to groin puncture (MSU 142.5 [116.8, 171.0] versus EMS 131.5 [114.0, 159.8], p = 0.15). MSU patients spent more time on‐scene, (EMS arrival to ED arrival, 53.0 [45.0, 62.0] vs 27.0 [22.0, 33.0], p<0.001) however less time prior to EVT (door to groin puncture, 76.5 [54.8, 108.5] vs 94.0 [72.0, 123.0], p<0.001) with variable use of field CTAs and direct cath lab admission with ED bypass, yielding a net neutral result. The variability among site protocols is reflected in the range of median alert to groin puncture times (minimum 107.0 minutes, maximum 152.0). In the 222 patients undergoing EVT, median alert to recanalization time was 181.5 minutes [146.8, 225.5] in the MSU group and 190.5 [157.5, 227.5] in the EMS group (p = 0.47). Recanalization (Thrombolysis In Cerebral Infarction [TICI] 2b/3) was achieved in 76% of MSU and 70% of EMS (p = 0.32) with comparable rates of EVT complications (including hemorrhage, perforation, dissection, hematoma). 54% MSU and 44% of EMS LVO patients achieved good functional outcome (modified Rankin Scale [mRS] ≤ 2) at 90 days (p = 0.11). Conclusions : In tPA‐eligible LVO stroke patients, MSU management did not increase or expedite EVT treatment times as compared to standard EMS management. Future MSU processes should include field CTA with direct admission to cath labs to maximize the early treatment advantage this technology provides.

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Abstract WP76: Artificial Intelligence CTA Vessel Density Mapping to Enhance Identification of Large Vessel Occlusions in Mobile Stroke Unit

Stroke ◽

10.1161/str.51.suppl_1.wp76 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Kevin Brown ◽

Bryan Villareal ◽

Kenneth Harrell ◽

Mersedeh Bahr Hosseini ◽

Lucas Restrepo-Jimenez ◽

...

Keyword(s):

Stroke Unit ◽

Clinical Decision Making ◽

Vessel Density ◽

Large Vessel ◽

Stroke Patients ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Stroke Units ◽

Density Mapping ◽

Mobile Stroke Unit

Background: Equipped with CT scanners capable of imaging the brain parenchyma and vasculature, Mobile Stroke Units (MSU) have the ability to image, diagnose and treat stroke patients in the prehospital setting. Automated CTA vessel density mapping could enhance frontline neurologist scan review in identifying large vessel occlusion (LVO), ensuring appropriate patient diagnosis and routing. Methods: We analyzed consecutive acute ischemic stroke patients undergoing CTA imaging in a regional Mobile Stroke Unit. Automated CTA vessel density mapping was performed in the field immediately after scan completion. CTA source images were wirelessly transferred to an off-site processing server (RAPID.Ai, IschemiaView) for artery reconstruction and color-coded density mapping, with blue, green, yellow, and red color shading indicating vessel density decreases of 70%-85%, 60%-75%, 45%-60%, and <45%. Results: Among all 16 patients, median processing time was 186 secs, and all images were available in time to aid clinical decision-making. Overall, automated processing yielded evaluable images in 94% (suboptimal contrast opacification precluded analysis of 1). Of the 15 diagnostically adequate exams, 100% (15/15) showed concordance for identification of anterior circulation occluded/abnormal vessel territories between automated CTA vessel density mapping and expert physician final CTA interpretation. Cases included true positives in 7, and true negatives in 8. Among true positives, CTA vessel density mapping identified the symptomatic occlusion in 6/6 and also correctly identified a severe cervical ICA stenosis unrelated to the clinical presentation in 1/1. Correctly detected intracranial occlusions included: ICA-17%. M1-17%, M1-M2 junction-17%, and M2-50%. Degree of vessel density diminution correlated with proximal-distal occlusion location. Conclusion: CTA vessel density mapping can feasibly and efficiently be conducted in Mobile Stroke Units and shows high accuracy in detection of large and medium intracranial vessel occlusions. Extension of mapping to the intracranial posterior circulation and algorithmic adjustment for proximal cervical stenoses/occlusions would further improve utility in aiding prehospital routing.

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Abstract P137: Large Vessel Occlusion Prediction Scale Thresholds That Are Sensitive for DAWN Trial Participants

Stroke ◽

10.1161/str.52.suppl_1.p137 ◽

2021 ◽

Vol 52 (Suppl_1) ◽

Author(s):

Kevin J Keenan ◽

Wade S Smith ◽

Ashutosh P Jadhav ◽

Diogo C Haussen ◽

Ronald F Budzik ◽

...

Keyword(s):

Scale Score ◽

Large Vessel ◽

Large Vessel Occlusion ◽

Infarct Core ◽

Vessel Occlusion ◽

Scale Scores ◽

Left And Right ◽

Item Scores ◽

Suspected Stroke ◽

Occlusion Prediction

Introduction: Large Vessel Occlusion (LVO) prediction scales are used to triage prehospital suspected stroke patients with a high probability of LVO stroke to endovascular therapy centers. The sensitivities of these scales in the 6 to 24 hour window are unknown. Higher scale score thresholds are typically less sensitive and more specific. Knowing the highest scale score thresholds that remain sensitive could inform threshold selection for clinical use. Sensitivities may also vary between left and right sided LVOs. Methods: LVO prediction scale scores were retrospectively calculated using the NIHSS sub-item scores of patients enrolled in the DAWN Trial. All patients had last known well times between 6 to 24 hours, NIHSS scores ≥ 10, intracranial ICA or proximal MCA occlusions, and mismatches between their exam severities and infarct core volumes. Scale thresholds with sensitivities ≥ 85% were identified. Scores ≥ 5% more sensitive for left or right sided LVOs were identified. Specificities could not be calculated because all DAWN Trial patients had LVOs. Results: 201 out of 206 patients had the required NIHSS sub-item scores. The highest score thresholds that maintained sensitivities ≥ 85% are bolded in the table. Conclusions: CPSS = 3, C-STAT ≥ 2, FAST-ED ≥ 4, G-FAST ≥ 3, RACE ≥ 5, and SAVE ≥ 3 are likely the highest thresholds that can be selected for extended window LVO triage without missing more than 15% of DAWN Trial eligible LVO strokes. For CPSS and SAVE, these are higher than the thresholds suggested by prior studies. CPSS = 3 and RACE ≥ 5 were more sensitive for right sided LVOs. These findings represent the maximum anticipated sensitivities of LVO prediction scales since the NIHSS scores were documented in hospitals during a clinical trial rather than in the prehospital setting. Inclusion of lower NIHSS or more distal LVO patients would lower sensitivities further. Selecting even higher scale thresholds for LVO triage would lead to many missed LVO strokes.

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