Aspirin in Acute Stroke

Aspirin is part of the emergency treatment of acute myocardial infarction. There is now good evidence that it should be part of the routine treatment of patients with acute ischaemic stroke. This was the main theme of Peter Sandercock, Professor of Medical Neurology at the University of Edinburgh.

The first need for a person with acute stroke is a brain scan: if it shows a haemorrhage, aspirin should not be given. Most strokes, however, are ischaemic and soon after the onset of symptoms of ischaemic stroke, the brain can appear normal on X-ray CT scanning. Magnetic resonance scanning is more sensitive than CT and can detect changes in the brain within the first hour. MR can even show the blocked artery which caused the ischaemic stroke. However, aspirin will not unblock an artery: this needs a thrombolytic drug. But, if an artery has unblocked itself, aspirin may help to keep it open and keep the arteries supplying blood to the damaged brain, minimising ischaemic damage.

Two large trials have studied the effects of aspirin started within the first 48 hours of stroke onset. Patients in the Chinese Acute Stroke Trial and the International Stroke Trial (about 20,000 patients in each study) were seen within 48 hours and randomised to aspirin or control. All patients were started on long term aspirin at hospital discharge. In the International Stroke Trial, two thirds of patients had a CT scan before treatment started; the remainder had a CT scan soon after trial entry. In the Chinese Acute Stroke Trial 87% had CT scans before treatment.

The benefit of aspirin in both trials was a reduction in the risk of recurrent ischaemic stroke. Although there was a small increase in the risk of haemorrhagic stroke (of about 1 or 2 per 1000 patients treated with aspirin) there was clear net benefit: for every 1000 patients with acute stroke treated with aspirin 9 avoid death or non fatal stroke. Furthermore, in the longer term, aspirin reduced the number of patients who were dead or needed help in everyday activities of daily living and, in addition, increased the chances of making a complete recovery from the stroke.

Professor Sandercock concluded that aspirin is beneficial, for a wide variety of patients with acute ischaemic stroke. If CT scanning is not immediately available, treatment may be started while a scan is being arranged (of course if a subsequent scan shows that the stroke was due to haemorrhage, the aspirin should be stopped). About a third of patients with acute stroke have difficulty swallowing safely. For such patients, the aspirin may conveniently be given as a suppository.

At a rough estimate, about five million patients each year world-wide have an acute ischaemic stroke. If just one million get to medical attention within the first 48 hours of onset and receive aspirin then 10,000 patients would avoid a poor outcome after stroke, and in addition about the same number would make a complete recovery. aspirin should therefore become part of the routine treatment of patients with acute ischaemic stroke, not just in the developed world but also in the developing world.

Box 3. aspirin should not be withheld from patients with acute stroke because of fears about bleeding. Two large trials have shown that it is beneficial (reducing mortality and post-stroke morbidity) in acute stroke – extra bleeding due to aspirin occurs in only one or two per thousand cases. The benefits far outweigh the risks. However, more CT scans to distinguish between ischaemic and haemorrhagic stroke should be done in acute stroke patients so that those with haemorrhage can avoid even this small risk.