Stroke is the fifth leading cause of death in the US and the leading cause of both short and long-term disability. The two most common types of stroke are hemmorhagic where a vessel in the brain ruptures and causes bleeding and ischemic when a clot blocks a blood vessel and the supply of oxygen to the brain is cut off. Ischemic strokes are far more common and for those, the standard of care has been treatment with clot busting drugs, known as intravenous tissue plasminogen activator (IV t-PA).
Time is crucial in treating every stroke and that’s why it matters where treatment is given. IV t-PA is only effective is given within 4-5 hours of the stroke. Newer technology provides another option that is showing promise in patients who did not get care quickly enough or for whom the drugs to break up the clot were not successful.
In a new study conducted at the University of Calgary in Canada researchers analyzed data on patients treated with both IV t-PA and stent retrievers from the Solitaire With the Intention For Thrombectomy as PRIMary Endovascular Treatment (SWIFT PRIME) Trial. A stent retriever is a small metal device that can be threaded through an artery in the groin all the way to a clot in the brain. Once there it can latch on to the clot, capturing it its tracks and then bring it out through the artery.
The study showed that if a clot can be removed quickly, outcomes for the patients improve dramatically. Bringing back blood flow to the brain within 2.5 hours of symptom onset was associated with functional independence, or minimal or no disability, in 91 percent of patients. Patients who were treated within 2.5 hours were 10 percent more likely to recover with no functional impairments than treated between 2.5 and 3.5 hours after stroke onset. Every 60-minute delay after 3.5 hours resulted in a 20 percent lower likelihood of functional independence.
The problem is that not all stroke centers are equipped to perform the retrieval of a clot with stent retrievers. The recent study in Canada backs up the recommendation of the American Heart Association and the American Stroke Association’s guidelines published in the New Journal of Medicine in July 2015 which called for endovascular stent retrieval as a “Class 1 Level of Evidence A” recommendation, the strongest possible suggestion for any method of treatment.
Mayank Goyal, M.D., FRCPC, who was the lead author on the study said,
"The earlier that patients with acute ischemic stroke get to a hospital offering the appropriate treatment, the higher the likelihood is of a good outcome. Two-thirds of the patients in our study went directly to the endovascular-capable center and one-third went to a primary stroke center. For those who went to the stroke center, there was a loss of about two hours in overall workflow, which is pretty significant.”
The study is published in the journal Radiology. The video below talks more about stent retrieval for strokes and how they impact timeliness and patient outcomes.
y University of Calgary, Alberta American Stroke Association