Thrombolytic treatment with the clot-busting drug alteplase is the only available method of treating acute stroke caused by a blood clot in the brain. However, the treatment is only approved within three hours after onset of stroke, which means that relatively few patients manage to be in a position to receive treatment before this time threshold has been crossed.

Scientists at the Swedish medical university Karolinska Institutet and the international network SITS (Safe Implementation of Treatments in Stroke) recently presented novel findings that may question present recommendations. The study, which was published in the Lancet on 15 September, demonstrated that thrombolysis administered within three to four and a half hours after a stroke was just as safe as that given within the three-hour time window.

These results are now corroborated by a study published in the top-ranking journal New England Journal of Medicine and co-authored by scientists from Karolinska Institutet. The study in question was a randomised comparative analysis of thrombolysis administered in the 3 to 4.5-hour interval and a placebo control, and shows that thrombolysis is more effective than control treatment and that many patients had recovered after three months.

“Both studies support the idea that the time window for thrombolysis should be extended, and this from the perspective of both safety and efficacy,” says Professor Nils Wahlgren, who co-led both studies.

In this present study, 52.4 per cent of the patients who received thrombolysis recovered within three months, compared to 45.2 per cent of the placebo group – a statistically significant difference. A total of 418 patients received thrombolysis and 403 a placebo. The proportion of symptomatic haemorrhages was higher in the experimental group than in the control group, but no higher than in the currently approved 0 to 3-hour interval.

The results of the two studies are to be discussed at Karolinska Stroke Update, an international expert conference to be held from 16 to 18 November in Stockholm, at which a decision is due to be taken on whether the European guidelines should be changed.

Publication: ‘Alteplase Compared with Placebo within 3 to 4.5 Hours for Acute Ischemic Stroke’ Werner Hacke, Markku Kaste, Erich Bluhmki, Miroslav Brozman, Antoni Dávalos, Donata Guidetti, Vincent Larrue, Kennedy R Lees, Zakaria Medeghri, Thomas Machnig, Dietmar Schneider, Rüdiger von Kummer, Nils Wahlgren, and Danilo Toni, for the European Cooperative Acute Stroke Study (ECASS) investigators, New England Journal of Medicine, 25 September 2008

Earlier publication: ‘Thrombolysis with alteplase 3-4.5 h after acute ischaemic stroke: an observational study’, Nils Wahlgren, Niaz Ahmed, Antoni Dávalos, Werner Hacke, Mónica Millán, Keith Muir, Risto O Roine, Danilo Toni, Kennedy R Lees, for the SITS investigators, Lancet 16 September 2006

For further information, please contact:

Professor Nils Wahlgren
Department of Neuroscience
Tel: +46 (0)8-517 756 00 or +46 (0)70-484 14 99
E-mail: nils.wahlgren@karolinska.se

Katarina Sternudd, Press Officer
Tel: +46 (0)8-524 838 95 (forwarded to mobile)
Email: katarina.sternudd@ki.se

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