Prehospital Prediction of Large Vessel Occlusion in Suspected Stroke Patients

Background: Mechanical thrombectomy (MT) is the standard of care for acute ischemic stroke caused by large vessel occlusion, but is not available at all stroke centers. Transfers between hospitals lead to treatment delays. Transport directly to a facility capable of MT based on a prehospital stroke severity scale score has been recommended, if transportation time is less than 30 min.Aims: We hypothesized that an Emergency Medical Services (EMS) routing algorithm for stroke, using the Los Angeles Motor Scale (LAMS) in the field, would improve time from last known well to MT, without causing patients to miss the IV Thrombolysis (IVT) window.Methods: An EMS algorithm in the Baltimore metro area using the LAMS was implemented. Patients suspected of having an acute stroke were assessed by EMS using the LAMS. Patients scoring 4 or higher and within 20 h from last known well, were transported directly to a Thrombectomy Center, if transport could be completed within 30 min. The algorithm was evaluated retrospectively with prospectively collected data at the Thrombectomy Centers. The primary outcome variables were proportion of patients with suspected stroke rerouted by EMS, proportion of rerouted ischemic stroke patients receiving MT, time to treatment, and whether the IVT window was missed.Results: A total of 303 patients were rerouted out of 2459 suspected stroke patients over a period of 6 months. Of diverted patients, 47% had acute ischemic stroke. Of these, 48% received an acute stroke treatment: 16.8% IVT, 17.5% MT, and 14% MT+IVT. Thrombectomy occurred 119 min earlier in diverted patients compared to patients transferred from other hospitals (P = 0.006). 55.3% of diverted patients undergoing MT and 38.2% of patients transferred from hospital to hospital were independent at 90 days (modified Rankin score 0–2) (P = 0.148). No patient missed the time window for IVT due to the extra travel time.Conclusions: In this retrospective analysis of prospectively acquired data, implementation of a pre-hospital clinical screening score to detect patients with suspected acute ischemic stroke due to large vessel occlusion was feasible. Rerouting patients directly to a Thrombectomy Center, based on the EMS algorithm, led to a shorter time to thrombectomy.

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Abstract 30: Prediction Scale Thresholds Selected to Rule Out Large Vessel Occlusion Stroke Result in Very Low Positive Predictive Values and Many False Positives

Stroke ◽

10.1161/str.51.suppl_1.30 ◽

2020 ◽

Vol 51 (Suppl_1) ◽

Author(s):

Kevin J Keenan ◽

Wade S Smith ◽

Sara Cole ◽

Christine Martin ◽

J Claude Hemphill ◽

...

Keyword(s):

Large Vessel ◽

Large Vessel Occlusion ◽

Stroke Patients ◽

Vessel Occlusion ◽

Scale Scores ◽

Post Test ◽

Suspected Stroke ◽

Post Test Probability ◽

Test Probability ◽

Rule Out

Introduction: Many prior large vessel occlusion (LVO) prevalence and prediction scale accuracy studies have not had samples representative of a prehospital suspected stroke population. To address this, we studied emergency medical systems (EMS) identified prehospital suspected stroke patients brought to the Emergency Department (ED) at Zuckerberg San Francisco General Hospital from July 2017 to July 2018. Methods: Patients were eligible for the prevalence study if the EMS prehospital alert call included suspected stroke with a last known well time within 6 hours and a positive Cincinnati Prehospital Stroke Scale. LVO prediction scale scores were retrospectively calculated from arrival NIHSS subitems. We excluded patients missing NIHSS scores and scales requiring non-NIHSS data. LVO stroke included internal carotid, M1, M2, or basilar arteries. Diagnoses were determined by chart review. Prevalences, scale scores, and accuracy statistics were then calculated. We prespecified that negative results of scale thresholds must reduce the post-test probability to ≤5% to rule out LVO stroke and positive results must increase the post-test probability to ≥80% to rule in LVO stroke. Results: Of 220 EMS transported patients there were 30 LVO strokes (13.6%), 35 ICHs (15.9%), 45 non-LVO strokes (20.5%), and 110 mimics (50%). There were 184 patients eligible for the LVO prediction study. Table 1 shows the accuracy statistics of qualifying scale thresholds. False positive rates ranged from 58% to 80%. Only FAST-ED ≥7 resulted in a positive predictive value (PPV) of ≥80% but this missed 83% of LVO strokes. Conclusions: The prevalence of LVO stroke among EMS suspected acute stroke patients brought to our ED over one year was 13.6%. Prediction scale thresholds selected to rule out LVO stroke result in very low PPVs and many false positives. No scale achieved a PPV above 50% while maintaining a sensitivity above 50% suggesting limitations in the ability of scales to rule in LVO stroke.

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Factors associated with prominent vessel sign on susceptibility-weighted imaging in acute ischemic stroke

Scientific Reports ◽

10.1038/s41598-021-84269-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Hai-fei Jiang ◽

Yi-qun Zhang ◽

Jiang-xia Pang ◽

Pei-ning Shao ◽

Han-cheng Qiu ◽

...

Keyword(s):

Ischemic Stroke ◽

Large Vessel ◽

Susceptibility Weighted Imaging ◽

Regression Analyses ◽

Large Vessel Occlusion ◽

Stroke Patients ◽

Anterior Circulation ◽

Vessel Occlusion ◽

Factors Associated ◽

Univariate Analyses

AbstractThe prominent vessel sign (PVS) on susceptibility-weighted imaging (SWI) is not displayed in all cases of acute ischemia. We aimed to investigate the factors associated with the presence of PVS in stroke patients. Consecutive ischemic stroke patients admitted within 24 h from symptom onset underwent emergency multimodal MRI at admission. Associated factors for the presence of PVS were analyzed using univariate analyses and multivariable logistic regression analyses. A total of 218 patients were enrolled. The occurrence rate of PVS was 55.5%. Univariate analyses showed significant differences between PVS-positive group and PVS-negative group in age, history of coronary heart disease, baseline NIHSS scores, total cholesterol, hemoglobin, anterior circulation infarct, large vessel occlusion, and cardioembolism. Multivariable logistic regression analyses revealed that the independent factors associated with PVS were anterior circulation infarct (odds ratio [OR] 13.7; 95% confidence interval [CI] 3.5–53.3), large vessel occlusion (OR 123.3; 95% CI 33.7–451.5), and cardioembolism (OR 5.6; 95% CI 2.1–15.3). Anterior circulation infarct, large vessel occlusion, and cardioembolism are independently associated with the presence of PVS on SWI.

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