In 1975 the likelihood of dying in a hospital from a heart attack was 20%. The management of acute MIs took a drastic turn in the late 1980s: First with the use of aspirin, and then with the introduction of primary lytic therapy. Bridging therapy—lytic to percutaneous coronary intervention (PCI)—took over at the beginning of the millennium. When numerous studies demonstrated the benefit of primary PCI, EMS agencies began transporting all STEMI patients directly to PCI centers.
This revolution occurred due to both improved technique and care delivery innovation. EMS providers who started work in the 1980s and 1990s will remember this metamorphosis in cardiac care. Now stroke care is about to undergo a similar tectonic shift; the question is, are you ready?
On December 17, 2014, the New England Journal of Medicine published online the first positive randomized, controlled trial to support the direct removal of clot (embolectomy) in patients with a stroke produced by the occlusion of a major blood vessel at the base of the brain. This trial, named MR. CLEAN, took place in the Netherlands and, unlike other studies before it, only randomized patients with confirmed occlusions of the major brain vessels—MR. CLEAN randomized for a disease (a large vessel occlusion) whereas prior studies has randomized for symptoms.1
At the 2015 International Stroke Conference in Nashville, TN, a similar and powerful treatment effect for embolectomy was seen in the ESCAPE, EXTEND IA and SWIFT-PRIME trials, which also randomized patients with confirmed occlusions of the major brain vessels. A fifth trial, REVASCAT (performed in Spain), was also recently discontinued, presumably due to overwhelming efficacy in the treatment arm.2–4
In all of these trials, patients in the embolectomy arm were about twice as likely to achieve a good outcome as patients who received the current standard of care (IV tPA) alone. The benefit was seen in all primary and secondary outcome analyses with an absolute difference ranging between 13.5%–31% in the rate of functional independence; only 4–8 patients need to receive this treatment to achieve functional independence over standard therapy alone.1–4
These trials also revealed that mildly symptomatic patients (low NIHSS scores) with large vessel occlusions, as well as elderly patients (>80 years old), were also likely to benefit from mechanical embolectomy.1
Critical Treatment Window
The results of these trials will have a profound impact on the EMS community. The treatment window for both IV tPA and mechanical embolectomy is critically important. Large vessel occlusions account for approximately 10% of strokes. And this, once again, puts EMS systems at the front and center of a rapidly changing paradigm.
EMS agencies now have a real obligation to develop innovative triage strategies and consider direct transport of stroke patients only to facilities that offer both IV tPA and mechanical embolectomy in a timely, efficient manner. Indeed, the clinical impact of untreated large vessel occlusions is devastating, as more than 25% of patients will die and the rest will be disabled if denied access to direct clot removal.5
Whereas EMS uses STEMI to triage patients to a PCI center, the Society of Neurointerventional Surgery has introduced a new term to define stroke patients who have a similar acute vascular emergency. Emergent large vessel occlusion (ELVO) was coined in order to signal the healthcare community that stroke is an acute vascular emergency.6 With that, the primary goals for acute ischemic stroke diagnosis and management are now:
Determine the stroke is an ischemic stroke (not hemorrhagic);
Administer IV tPA for appropriate candidates as rapidly as possible;
Rapidly confirm or exclude the presence of a large vessel occlusion by CT angiography (CTA) or MR angiography (MRA);7
Have mechanical embolectomy teams available for those patients who require it.
Finding the EKG/STEMI Equivalent for ELVO
Now that ELVO, like STEMI, has been established as a disease entity, it is time for a revolution in our systems of care. The treatment effect of embolectomy for ELVO has non-linear decay–people fare much better the sooner they receive treatment. As such, we must focus our efforts in the field to triage these patients to centers that are embolectomy-capable (comprehensive stroke centers) at the time of the first transport.
Cleveland, Houston and Berlin, Germany, have proven that mobile stroke units can provide immediate access to a CT scanner, which decreases time to diagnosis, increases the rate and speed with which IV tPA is given, and enhances delivery of patients to comprehensive centers for embolectomy. CTA can also be performed in the vehicle, which would most specifically allow ELVO triage to comprehensive stroke centers. Indeed, CTA in the field would be the ideal EKG equivalent, but the concept is currently cost-prohibitive for many agencies. This technology will prove effective and evolve in the coming years, but what can we do now in 2015?
EMS agencies across the nation have already begun evaluating mechanisms to improve ELVO (severe stroke) triage in the field using clinical scoring systems like the NIH Stroke Scale (NIHSS), Cincinnati Prehospital Stroke Scale, L.A. Motor Scale (LAMS) and Rapid Arterial Occlusion Evaluation (RACE) Scale. The LAMS and RACE scales seem to hold the most promise, as NIHSS is a bit unwieldy and the Cincinnati Stroke Prehospital Scale really only reliably identifies if a stroke is present.
LAMS Expanding on the work of others, Drs. Evan Allen and Paul Banerjee published data using the LAMS to quantify the severity of a stroke.8 They retrospectively evaluated combined data from two different EMS groups in two different counties using in-field modified versions of two different stroke severity scales designed to predict the presence of a large vessel occlusion: the 3 Item Stroke Scale (3I-SS) and the Los Angeles Motor Scale (LAMS).
During the years 2007–2012, patients with the most severe suspected acute strokes were transported to a single CSC. Allen and Banerjee then calculated the rate of utilization of CSC-specific interventions and the length of stay based on in-field stroke severity scores. Study outcomes showed that 21% of patients with a LAMS score of 4 or 5 received a CSC-specific intervention.9
These studies support the concept that EMS can identify patients in the field with severe stroke-like symptoms that may require CSC-specific intervention. This algorithm has been successfully adopted by numerous agencies throughout the country.
More recently a group from Barcelona designed and validated a prehospital stroke scale to predict an ELVO, named the Rapid Arterial Occlusion Evaluation Scale. In a prospective cohort the study authors demonstrated a high correlation between the RACE scale and the gold standard NIH Stroke Scale used in hospitals by neurologists. Of the 357 patients studied, ELVO was detected in 21% and the tool was 85% sensitive for the detection of large vessel disease.10 Continued use, along with local and regional data collection, will determine how much of an impact the RACE Scale will make in patient outcomes.
Is There An App For That?
This past month, in Broward County, FL, five EMS agencies began working with two comprehensive stroke centers on an innovative pilot project.
Using the Pulsara app, the paramedics are harnessing the full capabilities of smartphones for rapid prehospital notification to the ED and acute stroke team members, consisting of the neurologist and neurointerventional surgeon on call. This initiative aims to determine whether early notification by EMS in the prehospital phase can reduce door-to-treatment times upon arrival at the ED. The combination of RACE score transmitted through the Pulsara app, along with telephone or FaceTime communication between the paramedics and neurointerventional surgeon, will trigger early and parallel activation of the cath lab team for faster delivery of treatments to stroke patients with ELVO.
Here we are again, two decades later, discussing improved techniques and innovation of current systems of care. Time is brain and, for too long, we have been content managing the consequences of stroke. Times have changed, the stakes are too high and patients entrust us with their lives. Be a part of the revolution!
References 1. Berkhemer OA, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. New Eng J Med, 2015; 372:11–20. 2. Goyal M, Demchuk AM, Menon BK, Eesa M, Rempel JL, Thornton J, et al. Randomized assessment of rapid endovascular treatment of ischemic stroke. New Eng J Med, 2015. 3. Campbell BC, Mitchell PJ, Kleinig TJ, Dewey HM, Churilov L, Yassi N, et al. Endovascular therapy for ischemic stroke with perfusion-imaging selection. New Eng J Med, 2015. 4. Saver JL, For the S-PI. Solitaire with the intention for thrombectomy as primary endovascular treatment for acute ischemic stroke. International Stroke Conference 2015. 5. Lima FO, Furie KL, Silva GS, Lev MH, Camargo EC, Singhal AB, et al. Prognosis of untreated strokes due to anterior circulation proximal intracranial arterial occlusions detected by use of computed tomography angiography. JAMA Neurology, 2014; 71:151–157. 6. Jayaraman MV, Hussain MS, Abruzzo T, Albani B, Albequerque FC, Alexander MJ, et al. Embolectomy for stroke with emergent large vessel occlusion (elvo): Report of the standards and guidelines committee of the society of neurointerventional surgery. Journal of Neurointerventional Surgery, 2015. 7. Smith WS, Tsao JW, Billings ME, Johnston SC, Hemphill JC, Bonovich DC, et al. Prognostic significance of angiographically confirmed large vessel intracranial occlusion in patients presenting with acute brain ischemia. Neurocritical Care, 2006; 4:14–17. 8. Nazliel B, Starkman S, Liebeskind DS, Ovbiagele B, Kim D, Sanossian N, et al. A brief prehospital stroke severity scale identifies ischemic stroke patients harboring persisting large arterial occlusions. Stroke, 2008; 39:2264–2267. 9. Allen E, Banerjee P, et al. EMS In-Field Acute Stroke Severity Screening for Preferential Triage to a Comprehensive Stroke Center in Orlando, Florida. Stroke, 2013; 44:A15. 10. Perez de la Ossa N, Carrera D, Gorchs M, Querol M, Millan M, Gomis M, et al. Design and validation of a prehospital stroke scale to predict large arterial occlusion: The rapid arterial occlusion evaluation scale. Stroke, 2014; 45:87–91.
Peter Antevy, MD, is an EMS medical director for Davie Fire Rescue, Coral Springs Fire Department, SW Ranches and American Ambulance in Florida. He is the associate medical director for Palm Beach County Fire Rescue, Miramar Fire Rescue and Seminole Tribe Fire Rescue. Antevy serves as medical director at Coral Springs Fire Academy and Broward College’s EMS program and is a pediatric emergency medicine physician at Joe DiMaggio Children’s Hospital. He is founder and chief medical officer of Pediatric Emergency Standards, Inc.
Ryan A. McTaggart, MD, is the director of neuroInterventional services at Cleveland Clinic Hospital in Weston, FL. He is a senior member of the Society of Neurointerventional Surgery and sits on the Standards and Guidelines Committee.
Mahesh V. Jayaraman, MD, is the director of interventional neuroradiology at Rhode Island Hospital in Providence, RI. He is also an associate professor of diagnostic imaging and neurosurgery at the Warren Alpert School of medicine at Brown University. He is a senior member of the Society of Neurointerventional Surgery and leads the Standards and Guidelines Committee.