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Treating acute ischemic stroke patients in a stroke emergency mobile unit (STEMO) boosted the percentage of patients who received thrombolysis within the "golden hour," according to a German study.

Nearly one-third of (32.6%) ischemic stroke patients who were transported in the special ambulance received thrombolysis, compared with 22% of patients who received conventional care (P<0.001), reported researcher , of the Charite-Universitatsmedizin in Berlin, and colleagues.

Hospital transport in the STEMO increased the number of tissue plasminogen activator (tPA) treatments within the critical window of 1 hour (the "golden hour") from symptom onset almost 10-fold, they wrote online in .

Golden-hour thrombolysis was associated with better short-term outcomes in the study population, they added.

STEMO is a specialized ambulance equipped with a CT scanner and a point-of-care lab, and staffed with a neurologist trained in emergency medicine, along with a paramedic, and a radiology technician. A neuroradiologist is on call to evaluate images acquired on board the STEMO via a teleradiology connection, the authors explained.

"The STEMO was deployed when the dispatchers suspected an acute stroke during emergency calls," they wrote. "If STEMO was not available (during control weeks, while the unit was in operation, or during maintenance), patients received conventional care."

STEMO in the U.S.

"The concept of pre-hospital thrombolysis is still relatively new, and experience is limited to few groups," the researchers wrote, adding that further improvements in time reduction for early tPA treatment can be expected with growing use.

The findings show that tPA treatment times can be significantly lowered with specially equipped and staffed ambulances, but the concept is still highly experimental and many questions remain, commented , of the University of Texas Southwestern Medical Center in Austin.

"We are at the very beginning of figuring out how this is going to be of benefit, but we will figure it out," Warach told MedPage Today. He added that it remains to be seen if mobile stroke units would be most beneficial in rural or urban settings.

The University of Texas Health Science Center in Houston began operating the first mobile stroke unit in May 2014. The center's, and colleagues are currently studying the feasibility, efficacy, and cost effectiveness of the ambulance-treatment strategy.

The Houston STEMO unit, which is often staffed by Grotta, has treated about two patients a week with about a 40% golden hour tPA treatment rate, he said.

"Obviously, this is very preliminary data," he told MedPage Today. "At this point we are conducting a demonstration project and the cost-benefit analysis will be critical if this strategy is going to be widely adopted."

He added that data on the Houston project, to be published next month in Archives of Neurology, will include some early cost-analysis data.

Study Details

Despite efforts to reduce the time to tPA treatment for stroke, the vast majority of patients are not treated in the optimal golden hour after the onset of stroke symptoms, and a large percentage of eligible patients still receive no thrombolytic therapy.

In the Safe Implementation of Thrombolysis-Stroke Monitoring Study (SITS-MOST) registry, 10.6% of 6,483 patients were treated within 90 minutes and only 1.4% within 60 minutes. The median symptom onset to treatment (OTT) in the SITS-International Stroke Thrombolysis Register was 145 minutes, the researchers noted.

"Structured approaches have been successful in increasing thrombolysis rates and shortening door-to-needle times," Ebinger and colleagues wrote. "Centers with greater numbers of tPA treatments per year tend to have shorter door-to-needle times compared with smaller centers. However, some of the centers with shortened door-to-needle times still have long pre-hospital times."

In an earlier analysis of the Berlin program, Ebinger and colleagues showed that the STEMO unit approach could shorten treatment times for stroke patients. In their latest analysis, the researchers examined the impact on STEMO on golden-hour thrombolysis and outcomes.

The prospective, controlled Prehospital Acute Neurological Treatment and Optimization of Medical Care in Stroke (PHANTOM-S) study included 6,182 consecutive adult patients with probable stroke delivered to a Berlin hospital by STEMO or regular ambulance between May 2011 and January 2013.

Thrombolysis was started in STEMO if a stroke was confirmed and no contraindication was found.

The main outcome for the analysis was rate of golden hour thrombolysis, 7- and 90-day mortality, secondary intracerebral hemorrhage, and discharge home.

Thrombolysis rates in ischemic stroke were 200 of 614 patients when STEMO was deployed and 330 of 1,497 patients when conventional care was administered. Among all patients who received thrombolysis, the proportion of golden hour thrombolysis was six-fold higher after STEMO deployment (31% versus 4.9%, P<0.01).

The median OTT was 50 minutes in golden hour thrombolysis versus 105 minutes in all other thrombolysis (P<0.001). In patients who received golden hour thrombolysis, median NIHSS score was higher than in patients who received tPA more than 60 minutes after symptom onset.

Compared with patients with a longer time from symptom onset to treatment, patients who received golden hour thrombolysis had no higher risks for 7- or 90-day mortality (adjusted odds ratios 0.38, 95% CI 0.09-1.70, P=0.21 and aOR 0.69, 95% CI 0.32-1.53, P=0.36). They also were more likely to be discharged home (aOR 1.93, 95% CI 1.09-3.41, P=0.02).

Mobile Stroke Unit 'Here to Stay'

In an accompanying editorial, Warach wrote that the Berlin study showed that STEMO can significantly shorten time to thrombolytic treatment, which should translate into clinical benefit.

"Let there also be no doubt that the mobile stroke unit is here to stay and is starting to disseminate into pre-hospital stroke care," he wrote. "Many questions need to be answered in order to determine the appropriate niche where the benefit justifies the intensive use of resources that this approach requires. It is the duty of the early adopters to resist the temptation to uncritically embrace this approach as a certain good and to address these issues through rigorous clinical investigations."

Warach told MedPage Today that the Berlin and Houston experiences should help answer important questions about the efficacy and cost of stroke-dedicated emergency response units and he applauded both groups' efforts.

One important question which the Houston researchers are examining is whether trained neurologists need to be physically present in the STEMO unit if telemedicine technology is available.

Grotta said their early experience suggests that similar outcomes can be achieved using telemedicine.

"There are situations where telemedicine may not be as accurate or feasible as having a neurologist on site," he said. "Having done it for several months, I can say telemedicine seems to be working, but it is not a slam dunk."

From the American Heart Association:

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