More Canadian stroke patients could get clot-grabbing treatment

A procedure that allows doctors to pull stroke-causing blood clots out of patients' arteries could now save more lives and prevent more disabilities in Canada, the Heart and Stroke Foundation says.

The procedure, endovascular thrombectomy (EVT), was previously OK'd for use up to only six hours after a stroke. But on Thursday, the foundation announced it had changed its guidelines, extending that window to 24 hours. 

New research suggests EVT could benefit one in five Canadian stroke patients, said Patrice Lindsay, stroke director for the Heart and Stroke Foundation. Previously, experts thought the treatment was only viable for 10 to 15 per cent of patients.

Watch how a clot in the brain of a person having a stroke is cleared with a device 0:22

Last February, when the American Heart Association announced it was changing its maximum timeline for EVT (also called mechanical thrombectomy) to 24 hours, the foundation confirmed it was also planning to change the guidelines in Canada. The results of the new studies, which were announced at a European conference in May, offered compelling evidence that even more patients could benefit from EVT many hours after having a stroke, Lindsay said.   

During the procedure, physicians insert a stent into the patient's groin and thread it up through the blood vessels to reach a clot — that is blocking a major artery supplying blood to the brain — and pull it out.  

EVT is only useful in cases of ischemic strokes (strokes caused by a blood clot), as opposed to those caused by a bleed in the brain. Health-care providers assess whether to use EVT on a case-by-case basis, using an advanced CT scan to see exactly where the clot is and whether it can be removed with minimal risk of causing additional damage.

Doctors also use CT imaging to see how much brain tissue has died in the area where the stroke occurred, and how much can be saved. It was previously thought that after six hours, there wasn't enough surviving tissue left to justify doing an EVT —  but there's now evidence to the contrary, prompting the extension to 24 hours.

'Catastrophic' strokes 

The extension will especially affect people who live in remote and rural communities, Lindsay said. 

Because EVT is a highly specialized procedure, it is only performed in 23 hospitals across Canada. That means many stroke victims who live far from an urban centre, and who had to be transferred, "would never have made the six-hour time window," she said. 

That's been a worry for Dr. Ayman Hassan, a neurologist at Thunder Bay Regional Health Sciences Centre in northern Ontario. 

The hospital has one neurosurgeon who does EVT, but if he's not there, patients who need the procedure have to be transferred to Winnipeg or to health-care centres in southern Ontario. Stroke patients also come to Thunder Bay from remote communities. 

In the past, some patients who would have been eligible for EVT have run out of time before being able to get the treatment, Hassan said. With the new 24-hour time frame, he expects about 30 patients a year at his hospital will escape the "catastrophic" disability or death that this type of stroke brings.

The neurologist has seen the difference EVT can make, recalling a patient in his 60s who suffered a "significant stroke" last spring. 

"He was able to walk on his own and no residual weakness, no residual visual change, no residual sensory dysfunction," Hassan said. "So he almost recovered like it was a minor, non-disabling stroke."

Had that patient not had the treatment, he likely would have been left with serious disabilities, including trouble walking, speaking and swallowing, he said. 

The new time frame for EVT will also affect patients who have an ischemic stroke while sleeping.

"We now have opportunity for people who went to bed feeling fine and at whatever time they woke up, they were showing stroke symptoms, but there was no way of pinpointing exactly when that stroke occurred," Lindsay said. 

But the Heart and Stroke Foundation acknowledges the new guidelines have implications for Canada's already stressed health-care system.  

It's been working with provincial and territorial health ministries to prepare, Lindsay said, noting that screening more stroke patients to see if EVT is appropriate for them means an increased demand for immediate CT scans.

"All of the sudden everybody in that [24-hour] time window is critically urgent because we still have a chance to do something," she said. 

Although that extra time is "great" in circumstances in which delays getting treatment are unavoidable, Lindsay emphasized that "sooner is still better" when it comes to stroke.

"We still lose 1.9 million brain cells a minute [after a stroke], and the longer you wait, the more harm and damage and less positive recovery," she said. 

Recognize the signs

In all cases of stroke, the patient's best chance of recovery lies with the ability to recognize what's happening right away and get to the hospital immediately.  If you see someone showing signs of stroke, call 911 for an ambulance, the Heart and Stroke Foundation says. It uses the acronym FAST to help people remember the signs:

  • Face: Is it drooping?
  • Arms: Can you raise both?
  • Speech: Is it slurred or jumbled?
  • Time: To call 911 right away.

    

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