Doctors are being told not to routinely prescribe aspirin for a common heart condition that increases stroke risk.
Guidelines from the National Institute of Health and Care Excellence (NICE) are set to recommend other drugs instead for patients with an irregular heartbeat, called atrial fibrillation.
Warfarin or similar blood-thinning medicine is best, says NICE in draft advice to be finalised this month.
The advice will affect hundreds of thousands of patients.
But experts say most doctors already follow the advice to prescribe blood-thinners other than aspirin and that the guidelines are "playing catch-up" – this is the first time they will have been updated since they were first issued in 2006.
Atrial fibrillation (AF) is the most common heart rhythm problem, affecting up to 800,00 people – roughly one in 100 – in the UK.
In AF, the heart cannot work as well as it should and blood clots can form, which, in turn, increases the risk of a stroke.
Aspirin has been used for years to help protect patients from strokes, but mounting evidence suggests the drug's benefits are too small compared with other treatments.
The NICE guidelines for England and Wales look set to say that although daily aspirin might still be beneficial for some patients, most should be offered something else as well or instead.
According to its draft advice, NICE says warfarin or a newer type of oral anticoagulant is often best.
The British Heart Foundation said most doctors were already doing this.
Prof Peter Weissberg, medical director at the British Heart Foundation, said: "Strokes caused by atrial fibrillation are both common and preventable but only if the abnormal heart rhythm is identified in the first place and if effective drugs are given to prevent blood-clot development.
"The revised NICE guidance reflects accumulating evidence that warfarin and the newer anticoagulants are much more effective than aspirin at preventing strokes.
"This does not mean that aspirin is not important and effective at preventing heart attacks and strokes in other circumstances. Patients who are unclear on whether or not they should continue to take aspirin should speak to their doctor."
Prof Peter Elwood, an expert at Cardiff University, warned it could be unsafe to suddenly stop taking aspirin. "If aspirin is to be stopped, it should be stopped gradually," he said.
By Michelle Roberts
Source : www.bbc.com