College of Medicine & Veterinary Medicine

Stroke clot-buster trial shows benefits

Researchers find that stroke survivors are more able to look after themselves following treatment with rt-PA.

Patients given a clot-busting drug within six hours of a stroke are more likely to make a better recovery than those who do not receive the treatment.

The multi-centre, randomised study of more than 3000 patients is the world’s largest ever trial of the drug rt-PA, which is given intravenously to patients who have suffered an acute ischemic stroke.

The international trial - known as IST-3 - has found that for every 1000 patients given the clot-busting treatment within three hours of stroke, 80 more will survive and live without help from others than if they had not been given the drug.

The findings of the study, led by the University, have been published in The Lancet alongside an analysis of all other trials of the drug that have been carried out in the past 20 years.

Brain damage

An ischaemic stroke happens when the brain’s blood supply is interrupted by a blood clot.

The damage caused can be permanent or fatal. Stroke symptoms include paralysis down one side and speech problems.

Our trial shows that it is crucial that treatment is given as fast as possible to all suitable patients.

Professor Peter SandercockChief Investigator at the University’s Centre for Clinical Brain Sciences and Director of Edinburgh Neuroscience

Video interview


The work was supported by the University, the Medical Research Council, the Stroke Association UK, the Health Foundation UK, NIHR Stroke Research Network and NHS Lothian Health Board.


The benefits of using rt-PA do come at a price, say researchers.

Patients are at risk of death within seven days of treatment because the drug can cause a secondary bleed in the brain.

The research team conclude that the benefits were seen in a wide variety of patients, despite the risks.

The stroke experts stress that these mortality figures need to be taken in context of deaths from stroke. Without treatment, one third of people who suffer a stroke die, with another third left permanently dependent and disabled.

We have looked at data from more than 7000 stroke patients worldwide. What we see is that the drug increases patients’ longer term recovery. But we need to find out why some people bleed and how to reduce this to increase the effectiveness of clot busting treatment.

Professor Joanna WardlawIST-3 Imaging Lead, of the University of Edinburgh’s Centre for Clinical Brain Sciences

Related Links

College of Medicine and Veterinary Medicine

Centre for Clinical Brain Sciences

Edinburgh Neuroscience

Postgraduate study - Medicine and Veterinary Medicine

Undergraduate study - Medicine and Veterinary Medicine