The International Stroke Trial (IST): a randomised trial of aspirin, subcutaneous heparin, both, or neither among 19435 patients with acute ischaemic stroke. International Stroke Trial Collaborative Group.

Neither heparin regimen offered any clinical advantage at 6 months. The results suggest that if heparin is given in routine clinical practice, the dose should not exceed 5000 IU subcutaneously twice daily. For aspirin, the IST suggests a small but worthwhile improvement at 6 months. Taking the IST together with the comparably large Chinese Acute Stroke Trial, aspirin produces a small but real reduction of about 10 deaths or recurrent strokes per 1000 during the first few weeks. Both trials suggest that aspirin should be started as soon as possible after the onset of ischaemic stroke; previous trials have already shown that continuation of low-dose aspirin gives protection in the longer term.