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New procedure a ‘major breakthrough’ in stroke treatment: Canadian study

University of Calgary researchers Dr. Michael Hill, Dr. Mayank Goyal and Dr. Andrew Demchuk in the neuro-angiography suite where endovascular therapy is performed.

Riley Brandt/University of Calgary

A new stroke treatment has been shown to be so effective that Canadian researchers say they believe it will be used as part of standard stroke care.

The results of a new study, led by scientists at the University of Calgary's Hotchkiss Brain Institute and published online Wednesday in the New England Journal of Medicine, found a clot-retrieval procedure, called endovascular treatment, significantly decreased the incidence of disability or death among those who experienced acute ischemic stroke.

The treatment, which involves removing blood clots in the brain with a retrievable stent, also nearly doubled the percentage of patients who experienced positive outcomes from 30 per cent to 55 per cent.

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"That's a massive jump … [in] people going home, people going back to work, people being independent, people not having to live in nursing homes," says the study's co-principal investigator Dr. Mayank Goyal, a professor of radiology and clinical neurosciences at the University of Calgary's Cumming School of Medicine. "It's a major, major breakthrough in the disease."

Dr. Rick Swartz, a study collaborator, medical director of the stroke program at Sunnybrook Health Sciences Centre and an acting spokesman for The Heart and Stroke Foundation, says he thinks "Canada will be one of the first countries in the world to incorporate this treatment into our best practice guidelines."

Best practices for stroke care are developed by stroke experts across the country with funding from the foundation, which was one of the sponsors of the study.

The Canadian sites involved in the study, which already have the equipment and expertise, can begin using the procedure immediately, Dr. Goyal says.

In severe cases of ischemic stroke, blood clots block larger arteries at the base of the brain. Until now, the standard treatment has been to give patients a clot buster drug, known as tPA or tissue plasminogen activator, which dissolves clots and restores blood flow. For larger clots, this can be time-consuming – and in stroke care, "time is brain." For every minute the brain is starved of fresh oxygenated blood, it's believed about two million neurons die.

Though endovascular treatments have been evolving for two decades, the latest generation of stent retrievers are game-changers. Medical teams involved in the study – conducted at 11 sites across Canada and another 11 around the world, including the United States, Britain, Ireland and South Korea – were able to identify the blood clots and their location in the brain using advanced imaging, and then quickly extract them using stent retrievers, in some cases, within minutes.

The Canadian study, which involved 316 patients, is the first to show a decline in patient mortality: to one in 10 patients, compared with two in 10 patients when current standard treatment was used alone.

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Because the results demonstrated an "overwhelming effect" during an interim analysis, the study was stopped early, Dr. Goyal says.

It closely follows a previous study showing beneficial patient outcomes from endovascular treatment, conducted in the Netherlands and published online in the New England Journal of Medicine in December, and a separate study published Wednesday by Australian researchers that also demonstrated positive results.

Performed under X-ray guidance using injectable dyes, the procedure involves inserting a thin tube into the artery in the groin area, then threading a thinner tube, about two to three millimetres in diameter, into the neck. From there, an even thinner tube, about one millimetre in diameter, is guided into the brain to the site of the clot. A retrievable stent, which looks like a tiny mesh coil attached to the tip of a wire, is then routed through the tube and captures the blood clot, collapsing as it is pulled back out.

Dr. Goyal credits the success of the treatment, in part, to the speed at which participating medical teams were able to identify patients for whom endovascular treatment was appropriate and then carry out the procedure. The goal for getting from "picture to puncture" – imaging the brain, moving the patient and inserting the tube – was a median time of 60 minutes or less.

Not everyone who experiences ischemic stroke will fit the criteria for endovascular treatment, however. The treatment is for those who experience a moderate to severe stroke, whose symptoms are recent, and whose brain images show a large clot in an artery. The imaging must also show that some blood is able to detour around the blockage, buying doctors enough time for them to carry out the procedure.

Endovascular treatment does have some risks, including a very low risk of infection and bruising, as well as the risk of scraping or pushing the blood clot along the blood vessels, Dr. Swartz says. But, he says, "we know that people who get the procedure are doing much, much better than the people who don't. So even with those risks, the outcomes are better."

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About the Author

Wency Leung is a general assignment reporter for the Life section. Before joining The Globe in early 2010, she has worked as a reporter in Vancouver, Prague, and Phnom Penh. More

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