• Intravenous rtPA (or alteplase) works by breaking up clots blocking the flow of blood to the brain. (Getty Images)
The fatal risks associated with the controversial clot-busting drug for stroke patients, intravenous rtPA, could be reduced if administered at a low dose, according to a new study.
By
Yasmin Noone

11 May 2016 - 10:11 AM  UPDATED 12 May 2016 - 7:56 AM

Stroke patients given the controversial clot-busting drug, Intravenous rtPA, might have a greater chance of survival and a reduced risk of suffering a brain bleed,  if they received a lower dose than the standard amount currently administered in hospitals, a new Australian-led study has found.

Intravenous rtPA (or alteplase) works by breaking up clots blocking the flow of blood to the brain and is given to people suffering acute ischaemic stroke within the first few hours after the onset of symptoms.

Traditionally administered at a dose of 0.9mg/kg body weight, rtPA can go one of two ways: it can either save a person’s life and prevent disability resulting from a stroke, or cause a brain bleed and death in five per cent of all cases.

But now researchers believe they have come up with a compromise. A study released today, involving over 3,000 patients in 100 hospitals worldwide, finds that a lower dose of 0.6mg/kg could prevent deaths from strokes and reduce rates of serious bleeding in the brain, intracerebral haemorrhage (ICH), by two thirds.

“At the moment you could have a stroke but end up dying from a bleed in the brain,” says study lead author and senior director of the Neurological and Mental Health Division at The George Institute for Global HealthProfessor Craig Anderson.

“What we have shown is that if we reduce the dose level, we maintain most of the clot busting benefits of the higher dose but with significantly less major bleeds and improved survival rates."

“It’s largely unpredictable as to who will respond and who is at risk with rtPA.

“What we have shown is that if we reduce the dose level, we maintain most of the clot-busting benefits of the higher dose but with significantly less major bleeds and improved survival rates.

“On a global scale, this approach could save the lives of many tens of thousands of people.”

The Stroke Foundation says 26 per cent of ischemic stroke patients in Australia receive disability reducing thrombolysis treatment within 60 minutes of hospital arrival.

Maurice Wilson, 57, had a stroke and was administered the standard, higher dose of rtPA at Sydney’s Royal Prince Alfred Hospital under a month ago.

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“My wife and I had watched one of those medical programs recently, which talked about this drug and said it could reverse your stroke if you take it soon after having an attack,” explains Mr Wilson. “So my wife had no hesitation in saying yes to it for me [as I couldn’t talk or give consent].

“They administered it and within about 20 minutes, I could feel my arm again and was talking better. It was quite a miracle actually. It’s given me quality of life for sure. If I hadn’t had it, I’d be a lot worse.”

Mr Wilson understands that consenting to the drug is like playing Russian roulette: the result could have worked against him and caused a fatal brain bleed.

“I don’t know why it worked really well for me and it doesn’t work for other people. But they say, I was the best result they had ever seen.”

Stroke Foundation clinical council chair, Associate Professor Bruce Campbell, advocates the administration of the drug, in cases where risks of fatal brain bleeds are balanced against the high risk of severe disability associated with untreated stroke.

“I don’t know why it worked really well for me and it doesn’t work for other people. But they say, I was the best result they had ever seen.”

“tPA, or thrombolysis, is currently recommended as a leading treatment for ischaemic stroke in Australia and around the world,” says A/Prof Campbell.

“It is crucial that tPA is administered in stroke units, and emergency departments with appropriate expertise and infrastructure for monitoring, rapid assessment and investigation of patients with acute stroke.”

However, the Stroke Foundation is currently reviewing the stroke clinical guidelines, including the use of tPA.

The Australasian College of Emergency Medicine’s clinical care advice on stroke does not endorse use of IV rtPA and says it is applicable only to a minority of stroke patients, and should be seen as a treatment option indicated in carefully selected stroke patients, rather than a standard of care.

Although the study, published in the New England Journal of Medicine, found that the lower dose of rtPA reduced resulting deaths, it did not reduce the amount of people suffering a residual disability from a stroke.

The study’s authors and the Stroke Foundation say more research is needed to confirm the low dose as a treatment for use.

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