Time limit for stroke patients to have clot-removal procedure to be extended

Dr. Ayman Hassan still thinks about his past stroke patients who have been left with disabilities, wondering if more time to get them a specialized treatment would have improved their quality of life. 

In particular, the neurologist at Thunder Bay Regional Health Sciences Centre in northern Ontario remembers a woman in her fifties who was exercising when she suffered a stroke.

“She arrived to our emergency department only 10 minutes after,” Hassan said. 

A CT scan showed a large blood clot blocking the major artery that supplies one hemisphere of the brain, he said. The team thought she could be a candidate for a relatively new procedure called endovascular thrombectomy, in which doctors insert a tiny tube into an artery in the patient’s groin, threading it up through the blood vessels in the body to reach the clot in the brain and pull it out.

Studies have shown that for many patients suffering strokes due to large blood clots, the procedure can dramatically reduce death rates, as well as the likelihood of serious disability. But current Canadian guidelines say an endovascular thrombectomy can only be performed within six hours of the patient’s stroke. 

When Hassan’s patient arrived at the Thunder Bay hospital, the only specialist who could do the procedure wasn’t available. As is often the case in northern Ontario locations, the next option was to transfer the patient by air ambulance to a centre in southern Ontario or to Winnipeg. 

How a thrombectomy works0:22

Hassan and his team raced against time, trying to arrange the transfer. But in the end, it just wasn’t possible to do it in the six-hour window. 

They performed surgery to reduce the pressure on the patient’s brain and saved her life, but she was left with disability.  

“She was able to recover to be able to walk supported, but she lost function of one side of her body,” Hassan said. “And of course employment, everything that she was doing [was affected].”

Patients like her, he said, could benefit from a change the Heart and Stroke Foundation is making in its stroke treatment guidelines, extending the window for endovascular thrombectomy from six hours to 24 hours.   

The change comes after both the Heart and Stroke Foundation in Canada and the American Heart Association reviewed research suggesting it’s possible for some patients to benefit from the procedure even after many hours have passed since their first symptoms of stroke.   

“Because of our geography, extending the window is quite important to us,” Hassan said.  That includes not only the city of Thunder Bay itself, but the remote communities it serves, including many First Nations that rely on air transport from their nursing stations to larger centres in medical emergencies.   

‘Opens up an opportunity’

Patients living in remote areas will be one of the groups most affected by the change, Patrice Lindsay, stroke director for the Heart and Stroke Foundation, told CBC News. 

“This opens up an opportunity for those small populations who would have otherwise been told, you know, there’s no logistical way to get you to the right place at the right time,” she said. 

“It gives us more room for those patients.”

The expanded timeframe could also help patients who are alone when they have a stroke, unable to call for help, and are found by another person hours later, Lindsay said. 

The other main group of patients who could benefit are those who suffer a stroke while sleeping, so it’s unclear after they wake up exactly how many hours have passed since it occurred, she said.  

CT scan ‘critical’

The American Heart Association already announced it was extending the timeframe for endovascular thrombectomy (also called mechanical thrombectomy) last week at the International Stroke Conference in Los Angeles.

Lindsay said the new Canadian guidelines would likely take effect this spring.  

She emphasized that although the change could make an enormous difference in the quality of life for those who would have missed out on the treatment due to time constraints, endovascular thrombectomy is only a viable treatment for about 10 to 15 per cent of stroke patients.  

It can only be used for ischemic strokes (strokes caused by a blood clot), as opposed to those caused by a bleed in the brain. The exact location of the clot is a factor, because doctors must be able to reach it safely, with minimal risk of causing other damage to the patient.

Using an advanced CT scan, stroke specialists must also determine whether or not enough brain tissue is left to save before proceeding with an endovascular thrombectomy, Lindsay said.  

“Getting that first CT scan is critical.  Nothing else happens until that scan because you have to know what you’re dealing with.”

Intravenous clot-busting drugs are another method used to treat ischemic stroke, although they can’t be used in patients taking certain medications, she said, and they aren’t always effective on larger clots.

The timeline for using clot-busting drugs is four-and-a-half hours after an ischemic stroke occurs. That guideline is not changing, she said, because the risk of causing bleeding outweighs the potential benefit to the patient after that amount of time passes. 

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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