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Background and Purpose: Shorter time-to-thrombolysis in acute ischemic stroke (AIS)is associated with improved functional outcome and reduced morbidity. We evaluate the effect of several interventions to reduce time-to-thrombolysis at an urban, public safety net hospital. Methods: All patients treated with tissue plasminogen activator for AIS at our institution between 2008 and 2015 were included in a retrospective analysis of door-to-needle (DTN) time and associated factors. Between 2011 and 2014, we implemented 11 distinct interventions to reduce DTN time.Here, we assess the relative impact of each intervention on DTN time. Results:The median DTN time pre-and postintervention decreased from 87 (interquartile range: 68-109) minutes to 49 (interquartile range: 39-63) minutes. The reduction was comprised primarily of a decrease in median time from computed tomography scan order to interpretation. The goal DTN time of 60 minutes or less was achieved in 9% (95% confidence interval: 5%-22%) of cases preintervention, compared with 70% (58%-81%) postintervention. Interventions with the greatest impact on DTN time included the implementation of a stroke group paging system, dedicated emergency department stroke pharmacists, and the development of a stroke code supply box. Conclusions: Multidisciplinary, collaborative interventions are associated with a significant and substantial reduction in time-to-thrombolysis. Such targeted interventions are efficient and achievable in resource-limited settings, where they are most needed.

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 and externally validate large vessel occlusion (LVO) stroke prediction scales with a focus on predictive values.MethodsAll 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%.ResultsOf 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.ConclusionsDiagnostic 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.

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.

Background: The Mission Protocol was implemented in 2017 to expedite stroke evaluation and reduce door-to-needle (DTN) times at Zuckerberg San Francisco General Hospital. The key system change was emergency medical service (EMS) provider transport of patients directly to CT on arrival. Methods: Patients were eligible for a Mission Protocol prehospital stroke activation if an EMS provider found a positive Cincinnati Prehospital Stroke Scale and a last known normal time within 6 hours. We performed a chart review to compare treatment metrics between the first year of Mission Protocol patients and patients from the year prior who were also brought in via ambulance with concern for stroke and a last known normal time within 6 hours. All patients who received thrombolysis as part of their initial evaluation and treatment were included. No outliers were excluded. Median Door to CT and DTN times were compared using two sample Wilcoxon rank-sum (Mann-Whitney) tests. Results: The Mission Protocol cohort had 236 patients and the comparison cohort had 112 patients with results described in the table. The Mission Protocol was associated with a 10 minute faster median door to CT time (p<0.00001), a 6 minute faster median DTN time (p=0.0046), a 22% increase in the proportion of patients treated within 45 minutes of hospital arrival (84% vs 62%), and a 12% increase in the proportion of patients treated within 60 minutes (92% vs 80%). There were 8 stroke mimics treated in the Mission Protocol cohort compared to 2 in the comparison cohort. Symptomatic intracranial hemorrhage only occurred in one Mission Protocol patient with an ischemic stroke. Conclusion: The EMS direct to CT based Mission Protocol was associated with faster median door to CT and DTN times. There was a 22% increase in the proportion of thrombolysis patients treated within 45 minutes or less. More stroke mimic patients received thrombolysis but symptomatic intracranial hemorrhage only occurred in one ischemic stroke patient.