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Building a Regional System of LVO Stroke Care

There are more than 700,000 strokes in the U.S. every year, and stroke is the No. 1 cause of disability in our country. It’s estimated that up to one third of ischemic strokes are large-vessel occlusion (LVO) strokes.1 These occur in the large blood vessels that supply the brain, specifically the internal carotid, middle cerebral, and basilar arteries. Given the large portions of the brain supplied with blood by these arteries, these types of ischemic strokes cause significant morbidity and mortality. 

The optimal therapy for ischemic stroke is timely reperfusion, and until 2015 there was only one proven option, tissue plasminogen activator (tPA), otherwise known as the “clot-busting drug.” This therapy was limited to patients who presented less than 4.5 hours from their time last known well (LKW) and could not be given in “wake-up” strokes. 

Then, in 2015, five landmark trials were published that demonstrated improved patient outcomes in LVO strokes when patients underwent clot removal with endovascular therapy (EVT, Figure 1).2 This procedure demonstrates improved neurologic outcomes in patients with ischemic LVO stroke up to 24 hours after LKW time (Figure 2).3,4 For patients this represents one of the most promising therapies since tPA was introduced over 20 years ago.

The Prepuncture Problem

For EMS systems, endovascular retrieval therapy presents unique challenges. The therapy is very time-sensitive, and delays in diagnosis and definitive revascularization therapy result in a diminished chance for favorable neurologic outcome.2 The current recommended door-to-puncture time for LVO stroke is less than 90 minutes, and less than 120 for door-to-reperfusion.4

This challenge is a game-changer for EMS, as now our question is not “stroke: yes or no?” but “stroke: yes or no, plus how bad?” We are now tasked with making the diagnosis, ruling out mimics, using a severity scale to assess LVO risk, and determining the patient’s disposition to a stroke center capable of mechanical thrombectomy. 

The main prehospital issue in LVO diagnosis and therapy is not the effectiveness of mechanical EVT, but how the appropriate patients are identified, worked up, and expedited to the EVT procedure. It has been coined the “prepuncture problem.” The EMS community, along with our hospital partners worldwide, is engaged in defining the best processes and diagnostic instruments to afford patients the optimal clinical outcomes. 

Montgomery County Hospital District EMS (MCHD) is a non-fire-based EMS service in Montgomery County, Texas. We respond to approximately 65,000 calls to service and identify stroke in more than 500 patients a year. Our EMS system covers an estimated 1,100-square-mile service area and has more than 200 ALS medics supported by over 1,000 EMTs among our county’s 13 first responder organizations. 

In late 2015 MCHD began a regional quality improvement project in Southeast Texas to improve coordination of stroke care between EMS and our hospital partners. This began when the clinical team at MCHD engaged regional stakeholders to improve times to revascularization therapy in large vessel occlusion strokes. The goals of this initiative were improved stroke care by production of a best-practices clinical algorithm, shared educational resources, and a system to measure outcomes.

An Endovascular Pathway

MCHD, along with the Southeast Texas Regional Advisory Committee (SETRAC) and our regional healthcare systems, developed a novel stroke assessment endovascular pathway (Figure 3). This pathway demonstrates best practices for EMS to assess for LVO stroke and provides guidelines for appropriate patient disposition. 

The Southeast Texas region consists of a vast area surrounding Houston and has more than 100 EMS agencies. This presented the complex logistical issue of how to provide specialized training for LVO stroke that included specific field screening instruments for this wide array of prehospital providers. To address this challenge, MCHD, along with our partners at Houston Methodist The Woodlands Hospital, developed a training video for EMS providers on best practices for LVO stroke and endovascular therapy. The video covers the epidemiology of stroke and LVO, pertinent anatomy, and diagnostic priorities and considerations, and provides demonstrations of two of the most popular LVO screening tools: the Rapid Arterial Occlusion Evaluation (RACE) and Los Angeles Motor Score (LAMS). These are both quantitative stroke screens for LVO and provide moderate to good differentiation for LVO detection. 

The training video, along with a narrated lecture presentation and assessment tests, will be hosted through a regional learning management system on the SETRAC website. This package will allow area EMS organizations to access the training free of charge and will track compliance across the region. MCHD will also host these resources on its website

Another novel educational resource is the MCHD Paramedic Podcast. The podcast is a free open-access medical podcast developed in 2018 by MCHD Associate Medical Director Casey Patrick, MD, and the MCHD Department of Clinical Services. We publish a new episode every two weeks, and topics are targeted to EMS professionals. Topics center on common EMS patient complaints with an emphasis on the top differential diagnosis killers for each disease process. There is also a robust “back to the basics” series that serves as foundational education for our EMT-Basic listeners and reinforces the textbook foundations we rely on as advanced providers. 

The podcast was initially developed as a regional training platform for MCHD medics and first responders but now has a worldwide following, with more than 100,000 downloads in more than 50 countries. In May 2018 we released an initial LVO education episode featuring EMS stroke leader Peter Antevy, MD (Episode 9). A follow-up episode gathered a panel of regional neurointerventional experts to update listeners on the latest developments in endovascular clot retrieval for LVO stroke (Episode 53). 

The outcome of this effort by our clinical team and regional partners has been phenomenal. We’ve seen times to reperfusion therapy cut in half since the inception of this initiative. Montgomery County door-to-groin-puncture times are consistently less than 90 minutes. This represents a phenomenal process improvement in our system of care that exceeds the AHA’s current Get With the Guidelines Target: Stroke best-practice recommendation.

Quality Assessment

At MCHD our clinical team and business analysis unit assure excellent quality of care for our patients with a data-driven approach. For stroke care this involves immediate feedback to our crews on the outcome of each case and a system performance feedback process where hospital data is utilized to measure regional system performance. 

Obtaining individual crew feedback on the outcomes of patients has always been a struggle in EMS. There are multiple academic papers on regional systems of stroke care, and without fail one of their most common recommendations is to develop a feedback loop that includes EMS providers learning the clinical outcomes of their cases. In the past our EMS stroke specialist followed these cases in conjunction with the hospital stroke coordinator and then provided individual medics their feedback in a delayed, multistep fashion. This method was time-consuming and inadequate given the inherent time lags between EMS involvement in stroke cases and the hospital team’s feedback. 

MCHD plans to improve our care of time-sensitive emergency patients (stroke, STEMI, OOHCA, trauma, sepsis) with the implementation of a mobile communication platform that unites care teams involved in complex stroke activation cases (EMS, emergency department, neurology, radiology, neurovascular, and critical care). Stroke team activation occurs via EMS directly from a medic’s smartphone or tablet. When a case is completed, the follow-up for all team members will be immediate, and case feedback will occur in real time for the entire team. We believe implementing this technology will decrease onset-to-reperfusion times, improve regional coordination of care, and give our medics real-time feedback on their stroke cases, ultimately translating into improved neurologic outcomes for our patients.

At MCHD our clinical team and business analysis unit recently developed an automated performance feedback system. The process allows for nearly real-time feedback on regional performance. This system utilizes a novel automated process to collect data: When EMS closes a case with the primary impression of stroke, an automated e-mail is sent to that hospital’s stroke coordinators. This e-mail contains a link to our data tool, which is preformatted with the EMS data and has a series of simple data elements for the hospital system to complete. This data is collated and utilized to produce graphical representations for overall system performance. The tool tracks compliance for data submission within two weeks, EMS time metric compliance, hospital time metric values (CT/CTA/CTP times, along with reperfusion times, both tPA and groin puncture), and hospital admission and discharge stroke disability assessments. Area stakeholders meet regularly at a vascular case conference hosted by MCHD. This joins MCHD EMS providers with our neurology and neurosurgical partners to discuss shared cases in an effort to educate and continue the search for new innovations.

MCHD would like to acknowledge our regional partners: the Southeast Texas Regional Advisory Council (SETRAC) Stroke and EMS committees; Abhishek Agrawal, MD, Sabih Effendi, MD, and Jared Cosper, LP, MHA, of Houston Methodist The Woodlands Hospital; Yazan Alderazi, MD, of Memorial Hermann The Woodlands Hospital; Jeremiah Johnson, MD, of CHI St. Luke’s Health–The Woodlands Hospital; and HCA Houston Healthcare. The authors would also like to acknowledge clinical team authors Jordan Anderson, LP, CCP-C, Kevin Crocker, LP, FACPE, Coty Aiken, LP, Andy Adams, LP, NRP, and Joe Fioretti, LP, NRP. 


1. Mozaffarian D, Benjamin E, Go A, et al. Heart disease and stroke statistics—2015 update: A report from the American Heart Association. Circulation, 2015; 131(4): e29–e322.

2. Goyal M, et al.; HERMES collaborators. Endovascular thrombectomy after large-vessel ischaemic stroke: A meta-analysis of individual patient data from five randomised trials. Lancet, 2016; 387(10,029): 1,723–31.

3. Nogueira RG, et al. Thrombectomy 6 to 24 Hours after stroke with a mismatch between deficit and infarct. New Eng J Med, 2018; 378(1): 11–21. 

4. Albers G, et al. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. New Eng J Med, 2018; 378: 708–18. 

5. English JD, et al. Mechanical thrombectomy-ready comprehensive stroke center requirements and endovascular stroke systems of care: Recommendations from the endovascular stroke standards committee of the Society of Vascular and Interventional Neurology (SVIN). Interv Neurol, 2016; 4(3-4): 138–150. 

Casey B. Patrick, MD, FACEP, is assistant medical director for Montgomery County Hospital District EMS and a practicing emergency physician in multiple community emergency departments in the Greater Houston area. 

Robert L. Dickson, MD, FAAEM, FACEP, FACEM, completed emergency medicine training at Indiana University in 2004. He is EMS medical director at Montgomery County Hospital District EMS and is an assistant professor of emergency medicine at Baylor College of Medicine in Houston. 


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