Mobile Stroke Units Hasten Triage Even in Dense Cities

Dedicated ambulances that enable rapid stroke diagnosis and treatment while en route to the hospital deliver substantial time savings even in densely populated areas, data from a New York-based registry show.

Mobile stroke units (MSUs) are equipped with a CT scanner, intravenous tissue plasminogen activator (tPA), point-of-care blood testing, antihypertensive drugs, and antiepileptic drugs plus the usual equipment found in paramedic ambulances. In rural areas, they offer known benefits, but whether these advantages would be diluted by traffic and other big-city obstacles was uncertain, lead author Matthew Fink, MD (Weill Cornell Medicine, New York, NY), told TCTMD.

In the planning stages, the emergency medical services (EMS) leadership was initially resistant to the idea of MSUs, “because New York City [already] has a very, very well-developed EMS system in all five boroughs,” Fink said. “They were of the opinion that this would not add anything beneficial because traffic was terrible and there were so many hospitals around that were designated as primary stroke centers.”

But Fink says he saw an opportunity, given Manhattan’s density and large number of elderly patients with high stroke risk. Thus far, the effort has panned out and has expanded from one to three MSUs.

“It took us a long time to get our EMS people on board but . . . now they just love the program. They think it’s fantastic,” he commented.

Originating from NewYork-Presbyterian, the MSUs currently rely on philanthropy to cover their cost, according to Fink. On the whole, MSUs save money, he stressed to TCTMD. The question is how to pay upfront expenses in a fractured healthcare system, where the savings come further down the line.

METRONOME Registry

Led by Benjamin R. Kummer, MD (Icahn School of Medicine at Mount Sinai, New York, NY), Fink and colleagues collected data through the METRONOME (Metropolitan New York Mobile Stroke) registry on 66 patients with suspected acute ischemic stroke who were transported by a single MSU in Manhattan from October 2016, when the program was launched by NewYork-Presbyterian and the Fire Department of New York, through September 2017. This MSU operated on weekdays between 9 AM and 5 PM, serving both Columbia University Irving Medical Center and Weill Cornell Health.

For comparison, Kummer et al considered 19 patients who arrived at the hospital for stroke care via conventional ambulance during the same hours of operation (ie, weekdays 9 AM to 5 PM). Results were published online today in the Journal of the American Heart Association.

Baseline characteristics were similar in the two groups, and use of intravenous tPA was 43.9% in the MSU group and 47.4% in the standard-care group (P = 0.48).

The mean dispatch-to-thrombolysis time (primary endpoint) was 61.2 minutes with MSU care and 91.6 minutes with conventional care (P = 0.001). This difference was apparent despite the fact it took 6.5 more minutes for the MSU to arrive after dispatch (P = 0.002); that delay was offset by a 36.2-minute decrease in the time between ambulance arrival and thrombolysis (P = 0.001).

MSU-treated patients also were more apt to be picked up by ambulance closer to more designated stroke centers within a 2-mile radius (mean 4.8 vs 2.7 centers; P = 0.002) but tended to travel farther than those in conventional ambulances (mean 2.0 vs 1.2 miles; P = 0.03). There were no differences in population density between pickup locations for the two strategies.

After adjustment for clinical, demographic, and geographic factors like the number of nearby designated stroke centers and population density, MSU care was linked to a mean decrease in dispatch-to-thrombolysis time of 29.7 minutes compared with standard EMS.

‘Society as a Whole Will Benefit’

With the three MSUs, “we’ve given tPA to hundreds of patients and the timing has held up whether we’re in Manhattan, Brooklyn, or Queens,” said Fink. Thrombolysis is reaching patients approximately 40 minutes faster, he added. “That makes a big difference.”

During the first year, fellowship-trained stroke neurologists rode along on the MSU to interpret CT results in person, but after that the process was streamlined, Fink explained. “We now have one stroke neurologist that manages all three units simultaneously via telemedicine. In fact, we’ve had some occasions where we treated three patients in all three ambulances at the same time with thrombolytics, all simultaneously. All of it works very well, because you’ve got video screens, audio, [and] can flip back and forth between [units]. It’s like changing channels on a TV set.”

The New York data continue to be collected and are being pooled with numbers from similar programs in cities including Houston, Memphis, Denver, and Los Angeles as part of the federally funded BEST-MSU study, Fink reported.

Mobile stroke units do not necessarily have be citywide efforts, Fink pointed out. Retirement communities and other groups can also organize. And while the NewYork-Presbyterian program is funded through philanthropy, one key step to wider use of MSUs may be support through public entities, such as the Centers for Medicare & Medicaid Services, he suggested.

“We think if you look at the overall cost of care of patients with stroke that these units will save a lot of money,” Fink said. “If a patient is treated with a thrombolytic in the first 60 minutes and they completely recover and go home with normal function on day 2 and they don’t have to go for rehab and don’t have to stay in the hospital and they can go back to work 2 weeks later—if you add all those things up, it’s a great economic benefit.

“But because our system is so chopped up and fragmented, it doesn’t work that way. The people that spend the money upfront are not going to save the money downstream,” he observed. But with investment in MSUs, Fink said, “society as a whole will benefit.”

The New York-based initiative plans to expand further, he concluded. “With every passing day, there are more and more cities in the United States that are initiating these programs.”

Photo Credit: NewYork-Presbyterian