In a pilot programme in New York City, USA, a mobile interventional stroke team (MIST) travelled directly to patients to perform emergency stroke surgery instead of transferring stroke patients to a specialised stroke centre. This resulted in significantly less disability for patients three months after their stroke when compared to patients who lost valuable time in being transferred to a higher level stroke centre. These findings are published in Stroke, a journal of the American Stroke Association (ASA), which is a division of the American Heart Association (AHA).
In this study, stroke specialists at Mount Sinai Health System in New York developed a MIST model to bring endovascular thrombectomy to the patient. The MIST team was staffed with a neurointerventionist, a fellow in training or a physician assistant, and a radiologic technologist. The team travelled to the location of the patient to perform the endovascular thrombectomy procedure.
Medications to dissolve blood clots in large vessels within or leading to the brain are effective in about 15–20% of cases—but, most acute ischaemic stroke patients with a large vessel blockage also require endovascular thrombectomy to remove these large blood clots. Since 2015, endovascular thrombectomy has been the standard of care for stroke therapy and is detailed in the latest 2018 AHA/ASA stroke early management guidelines. Currently, the biggest barrier for stroke patients is timely access to this potentially life-saving procedure, an ASA press release states.
“Fewer than 50% of Americans have direct access to endovascular thrombectomy—the others must be transferred to a thrombectomy-capable hospital for treatment, often losing more than two hours of time to treatment,” said Johanna T Fifi, associate professor of neurosurgery, neurology and radiology in the Department of Neurosurgery at Mount Sinai’s Icahn School of Medicine in New York City, USA, and one of the study’s co-authors. “Every minute is precious in treating stroke, and getting to a centre that offers thrombectomy is very important. The MIST model would address this by providing faster access to this potentially life-saving, disability-reducing procedure.”
Researchers examined data from the New York City-based MIST trial, which focused on 226 stroke patients who received endovascular thrombectomy from January 2017 to February 2020 at four hospitals (one certified comprehensive stroke centre and three thrombectomy-capable stroke centres) within the Mount Sinai Health System.
Of those, 106 patients were treated by the MIST team, and 120 were treated using the drip-and-ship model of care, which requires the patient to be transferred to a hospital with expertise in endovascular thrombectomy. All patients in the analysis were functionally independent before having a stroke. Researchers compared 90-day functional outcomes between patients treated by MIST and those transferred to a stroke centre for endovascular thrombectomy. Using the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS) to assess outcomes, they analysed results from patients who were seen within six hours of stroke-symptom onset (early therapeutic window) and after six hours of stroke symptoms (late window).
The key findings were:
- For patients treated within six hours of stroke onset, the rate for a good outcome—an mRS score less than or equal to two, meaning they are mobile and can perform daily tasks—three months after the event was significantly higher in patients from the MIST group (54%) compared to the patients in the transferred group (28%).
- Among patients treated during the early window, functional outcomes at discharge were significantly better among the MIST patients than the transferred patients.
- For patients treated in the late window, outcomes were similar, with 35% of patients in the MIST group having a good 90-day outcome compared to 41% in the transferred group.
“Ischaemic strokes often progress rapidly and can cause severe damage because brain tissue dies quickly without oxygen, resulting in serious long-term disabilities or death,” Fifi said. “Assessing and treating stroke patients in the early window means that a greater number of fast-progressing strokes are identified and treated.”
The study’s findings are limited by the fact it was not a randomised study, the release concludes. Data for the New York City MIST trial were collected prospectively, but the analysis was done retrospectively. “The MIST approach to care continues, as more institutions and cities have implemented the model,” Fifi added.
“This study stresses the importance of ‘time is brain,’ especially for patients in the early time window,” said Louise McCullough, AHA/ASA chair of the International Stroke Conference (ISC), chair of the Department of Neurology at McGovern Medical School at the University of Texas Health Science Center, and chief of neurology service at Memorial Hermann Hospital, Texas Medical Center in Houston, USA.
“Although the study is limited by the observational, retrospective design and was performed at a single, integrated centre, the findings are provocative. The use of a MIST model highlights the potential benefit of early and urgent treatment for patients with large vessel stroke. Stroke systems of care need to take advantage of any opportunity to treat patients early, wherever they are.”
