By Matthew E. Fink, MD
Louis and Gertrude Feil Professor and Chair, Department of Neurology, Associate Dean for Clinical Affairs, New York Presbyterian/Weill Cornell Medical College
Dr. Fink reports no financial relationships relevant to this field of study.
SOURCE: Morey JR, Oxley TJ, Wei D, et al. Mobile interventional stroke team model improves early outcomes in large vessel occlusion stroke: The NYC MIST trial. Stroke 2020;51:3495-3503.
Since 2015, when multiple international trials were reported showing clear benefit for mechanical thrombectomy in patients with large vessel occlusions, this treatment has been the standard of care. However, the speed of treatment remains paramount for good outcomes, and different models have been developed around the world in different geographic settings. In some areas, patients are brought to a comprehensive stroke center immediately, but this may result in increased travel time in an ambulance and delay of treatment. Other regions use the drip-and-ship model, and still others use mobile stroke units for treatment with intravenous thrombolysis in the field, and then delivery to a comprehensive stroke center.
The Mount Sinai team in New York City has developed a mobile/roving team of interventionalists — the mobile interventional stroke team (MIST) — that rapidly travels to a thrombectomy-capable stroke center within their system to perform endovascular therapy when it is indicated. In this prospective observational study with three months of follow-up, performed between 2016 and 2018, the investigators evaluated time-to-treatment using various models of triage in their multicenter health system that has one comprehensive stroke center, four thrombectomy-capable centers, and several primary stroke centers. This was not a prospective, randomized trial, and there are many confounding variables that may have influenced the results.
The investigators compared four types of triage: 1) direct delivery to the comprehensive center; 2) drip-and-ship from the primary stroke center to the comprehensive stroke center; 3) MIST travel to a thrombectomy-capable center; or 4) a combination of drip-and-ship with patient transfer to a thrombectomy-capable center with MIST arrival. The primary prespecified endpoint of the study was initial door-to-recanalization time and secondary endpoints measured clinical outcomes at discharge and at three months.
Of 373 patients, 228 who received endovascular therapy were included in this analysis. Treatment by MIST had a faster door-to-recanalization time than the drip-and-ship model by a mean time of 83 minutes (P < 0.01). Time-to-recanalization was similar between the MIST triage approach and direct delivery to the comprehensive stroke center: 192 minutes vs. 179 minutes, respectively. In comparing clinical outcome and recovery, patients treated by the MIST triage model had a higher proportion of patients with complete recovery (National Institutes of Health Stroke Score 0-1) compared to those patients who were treated with the drip-and-ship model (37.9% vs. 16.7%, P < 0.01). Of the patients treated by MIST, 52.8% had a modified Rankin scale ≤ 2 at three months compared to 38.9% of patients treated by the drip-and-ship model.
The mobile interventional stroke team model shows great promise in rapid endovascular thrombectomy, but as an observational study, there are many confounding factors that may have influenced the outcomes and caused selection biases. And different geographies, such as a dense urban population vs. suburban or rural populations, may require different triage models for optimal outcomes.