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Mobile Stroke Units Yield Earlier Treatment with Endovascular Thrombectomy, Better Outcomes

Patients with large vessel occlusion who traveled to thrombectomy-capable stroke centers via a Mobile Interventional Stroke Team (MIST) received earlier treatment and had better outcomes at 90 days, according to a new retrospective study published in the August 5 online edition of Stroke.

Historically, patients have been sent either directly to comprehensive stroke centers (CSCs) or to CSCs following intravenous thrombolysis (the drip-and-ship model). The new stroke service delivery model allows an interventional stroke team that travels from the CSC to the thrombectomy-capable stroke center to perform EVT.

“The MIST model decreases initial door-to-skin puncture, as compared with the DS [drip-and-ship] model, which has translated to significantly improved 90-day outcomes in the early window," wrote lead author Johanna T. Fifi, MD, FAAN, associate professor of neurosurgery, neurology, and radiology and associate director of the Cerebrovascular Center at the Icahn School of Medicine at Mount Sinai in New York.“This may be because of the MIST capturing high risk fast progressors at an earlier time point."

The study looked at 561 cases—226 patients fit inclusion criteria and were categorized into either MIST or “drip and ship" teams. The primary clinical endpoint was the proportion of patients with a good functional outcome (defined as a modified Rankin Scale score—mRS—of ≤ 2). Secondary outcomes included the NIH Stroke Scale Score and mRS at discharge and at 90 days.

Researchers used the NYC MIST Trial data, as well as their own prospective stroke quality assurance database to add more recent data, for patients who received endovascular thrombectomy (EVT) between January 2017 and February 2020.

Fifty-four percent of those who were well less than six hours before—meaning they were treated in the “early window"—had a good 90-day outcome using the MIST module compared with 28 percent (p<0.01) in the DS model, wrote the study authors. The outcomes were similar for those treated in the late treatment window: 35.1 versus 41.4 percent, respectively, for the MIST vs. DS model (p=77).
The study authors pointed out that the DS cohort included more patients with chronic medical conditions and a different occlusion location distribution, that is, a greater proportion of middle cerebral artery occlusions versus other sites. The study was also limited by the retrospective analysis and observational nature, and the generalizability of these findings may be limited to large, integrated health systems in urban environments.
The challenge is that, while the MIST program has a larger impact in the early window, in the later window “we may be left with more slow progressors where the time to treatment effect is blunted,"  Dr. Fifi and her colleagues wrote.

Disclosures: Dr. Fifi reports research support from Stryker.

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Morey JR, Zhang X, Marayati NM, et al. Mobile interventional stroke teams improve outcomes in the early time window for large vessel occlusion stroke. Stroke 2021: Epub 2021 Aug 5.