Speeding Stroke Care With Mobile Units, Direct Angio Pays Dividends

Getting patients with acute ischemic stroke treated more rapidly—either through the use of a mobile stroke unit or by taking them directly to the angiography suite—increases the number of patients who receive proven therapies and improves clinical outcomes, show two trials presented during the virtual International Stroke Conference 2021 this week.

In the BEST-MSU study, patients initially treated in a mobile stroke unit equipped with mobile CT and able to administer tissue plasminogen activator (tPA) were more likely to receive it within the first “golden hour” and had better functional outcomes at 90 days compared with patients taken to the hospital in a standard ambulance, James Grotta, MD (Memorial Hermann – Texas Medical Center, Houston), reported.

And in the ANGIOCAT trial, reported by Manuel Requena, MD, PhD (Vall d’Hebron University Hospital, Barcelona, Spain), taking patients with large-vessel occlusions directly to the neuroangiography suite for endovascular therapy cut down on delays, increased the proportion of patients who received an intervention, and boosted 90-day functional outcomes.

“Taken together, they reflect the growing recognition of the importance of speed in the care of stroke patients. As we all like to say, time is brain,” commented American Heart Association President Mitchell Elkind, MD (NewYork-Presbyterian Hospital/Columbia University Irving Medical Center, New York, NY), during a media briefing. He noted that an estimated 2 million brain cells die for every minute of ischemia, stressing: “We have these great treatments, but speed is really of the essence.”

Louise McCullough, MD, PhD (University of Texas Health Science Center at Houston), chair of this year’s meeting, indicated that combining the results of the two trials—performing CT and administering tPA in the ambulance and then taking patients directly to the neuroangiography suite—“would be a perfect marriage of prehospital care and emergency care” to get treatments to patients more rapidly.

“Every minute counts, so wherever we can really reduce delays is going to make a huge difference to patients and their families,” she said. “So you can imagine . . . setting up a whole new system of care in network-type models where you can get the best of both worlds and you get rapid prehospital care that doesn’t delay you [getting] to the angio suite. So I think there’s a lot of potential possibilities and these studies are really leading the way in how we’re going to change the stroke systems of care as we gain more and more knowledge.”

BEST-MSU

Mobile stroke units have been introduced in cities around the world over the past several years. They are standard ambulances retrofitted to include portable CT scanners and point-of-care laboratories that allow an onboard team to identify patients eligible for thrombolytic therapy and deliver it before reaching the hospital.

Prior studies have shown that these specialized units speed the delivery of treatment, and the B_PROUD trial reported last year demonstrated that patients treated with a mobile stroke unit deployed in Berlin, Germany, had improved functional outcomes 3 months later.

Grotta, who was instrumental in bringing the first mobile stroke unit to the United States about 7 years ago, headed up the BEST-MSU trial to evaluate the impact of this approach in various American cities. The study pulled data from seven US sites: Houston, TX; Memphis, TN; Los Angeles, CA; Aurora and Colorado Springs, CO; New York, NY; Burlingame, CA; and Indianapolis, IN.

BEST-MSU included 617 patients treated by a mobile stroke unit and 430 who were taken to the hospital via standard ambulance. In the latter group, the mobile stroke unit team still responded to the scene to evaluate patients to ensure the two trial arms would be comparable.

Use of the specialized unit significantly increased the proportion of eligible patients who were treated with IV tPA within the first hour after the patients was last seen well (33% vs 3%). It also increased the percentage of patients treated with tPA within 4.5 hours (97.1% vs 79.1%; P < 0.001). Most of that difference, Grotta said, was due to the fact that emergency department physicians were less willing to administer treatment compared with the vascular neurologists staffing the mobile stroke unit.

Those differences translated into improved functional outcomes at 3 months. Patients treated in the mobile stroke unit had a significant advantage on a utility-weighted modified Rankin Scale (mRS; P = 0.002), which takes into account patients’ perceptions about the importance of transitions between various scores.

Most patients treated in the mobile stroke unit (55.0%) achieved an mRS score of 0 or 1, indicating functional independence, compared with 44.4% of those who received standard management (OR 2.43; P < 0.001).

Grotta said that for every 100 patients who receive treatment in the mobile stroke unit versus standard management, 27 will have lower levels of disability, including 11 who will be disability-free.

The investigators are also assessing outcomes and healthcare utilization through 1 year of follow-up, and those results will be reported later this year. Grotta predicted, though, that deploying mobile stroke units would be cost-effective in the right communities. Showing that, he said, would help overcome the main barrier to wider use of these units: the lack of reimbursement pathways for the care delivered on board.

ANGIOCAT

ANGIOCAT was designed to assess the impact of bypassing usual imaging protocols and taking patients arriving at the emergency department with suspected strokes caused by large-vessel occlusions directly to the neuroangiography suite for evaluation and possible thrombectomy.

The trial, conducted at a single high-volume center, included patients admitted within 6 hours of symptom onset who had a prehospital RACE score > 4 (the higher the score, the greater the likelihood of a large-vessel occlusion); an NIHSS > 10 at admission; and a premorbid mRS ≤ 2. Availability of the endovascular therapy team and an angiography suite were required. Investigators randomized 85 patients to follow a protocol that took them through standard CT imaging before heading to the neuroangiography suite and 89 to be taken directly to the neuroangiography suite. About one-third of patients presented directly to the thrombectomy-capable center, and the rest were transferred from another hospital.

Taking patients directly to the neuroangiography suite shortened the door-to-puncture time (median 18 vs 42 minutes) as well as the door-to-reperfusion time (median 57 to 84; P < 0.001 for both), with no difference in the interval between symptom onset and reperfusion (median 290.5 vs 326.9; P = 0.32).

The primary outcome was the mRS score at 90 days, with a shift analysis showing that direct transfer to the neuroangiography suite increased the likelihood of a 1-point improvement (adjusted common OR 2.2; 95% CI 1.2-4.1).

All patients who bypassed the CT suite underwent an intervention, compared with 88% in the standard arm, with no significant differences in various safety endpoints between the direct and control arms:

• Procedural complications (8.1% vs 2.7%; P = 0.6)
• Symptomatic hemorrhage (1.4% vs 4.1%; P = 0.28)
• Hemicraniectomy (2.7% vs 5.5%; P = 0.39)
• In-hospital mortality (9.0% vs 11.8%; P = 0.55)
• 90-day mortality (20.2% vs 32.9%; P = 0.07)
• Vascular access complications (2.7% vs 0; P = 0.16)

“This protocol improved clinical outcome, with a significant shift towards better outcomes across the spectrum of disability,” Requena said.