In the event of acute ischemic stroke, treatment with 'clot-busting' drugs – thrombolysis – should be administered as early as possible. Failure to do so might leave the treatment doing harm than good since it increases the danger of haemorrhage. Prevailing praxis is for thrombolysis to be given only to patients who reach hospital within three hours after the onset of stroke.

However, an international study led by Professor Nils Wahlgren at Karolinska Institutet now shows that it is safe to administer the treatment up to four and a half hours after the stroke.

The researchers compared 11,865 patients treated within three hours of stroke with 644 patients who, for various reasons, were treated within three to four and a half hours afterwards. The results show that the risk of haemorrhage complications and death was not significantly higher for the later treatment. Nor was there any difference between the two groups in the percentage of patients displaying impaired functionality in everyday activities three months after stroke.

"The data we are now publishing will make it possible for many more patients to receive thrombolysis," says Professor Wahlgren. "This is important, because it'll not only alleviate their suffering, but also help to reduce the costs of stroke for society."

Possible changes to the European guidelines for the treatment of stroke will be under discussion at Karolinska Stroke Update, a conference due to be held in Stockholm on 16-18 November. Here, consideration will also be taken of the results of another, as yet unpublished, randomised study co-led by Professor Wahlgren.

Note: If no author is given, the source is cited instead.

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