Millions of Britons who take aspirin to lower their risk of heart attacks and strokes would see an even greater benefit by switching to an alternative drug, scientists suggest.
People diagnosed with coronary heart disease are usually advised to take a daily aspirin to thin their blood and cut their risk of suffering a serious cardiac event.
Now, a review has found switching to an alternative blood thinner, clopidogrel, reduces the risk of heart attack, stroke or death by an extra 14 per cent.
The global research team, including scientists from Imperial College London, concluded that the alternative drug offered more protection and that there was a strong case to adjust recommendations to make clopidogrel the preferred option for patients.
Their findings were published in The Lancet medical journal and presented at the European Society of Cardiology congress in Madrid.
Coronary artery disease, or coronary heart disease, is the most commonly diagnosed type of heart disease and affects 2.3 million people in the UK.
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It occurs when arteries in the heart become narrowed by a build-up of atheroma, a fatty material within their walls. The discomfort felt from this narrowing is called angina, and if a full blockage occurs, it can cause a heart attack.
The team of researchers analysed seven randomised trials involving 28,982 patients with heart disease who had been taking clopidogrel or aspirin, known as antiplatelet medications.
After an average of five and a half years, those on clopidogrel were 14 per cent less likely to have suffered a heart attack, a stroke, or to have died from a heart-related condition.
The study looked at a range of patient groups, including some who had undergone procedures like stent replacement or acute coronary heart disease.
They found that even patients who should not have responded to clopidogrel as well, due to genetic or clinical factors, still experienced a greater benefit from it than from aspirin.
The review also found that the likelihood of major bleeding, a side effect of blood thinners, was no greater with clopidogrel. There were 256 total deaths or incidents of major bleeding in the clopidogrel group and 279 in the aspirin group, indicating they are similarly safe.
According to NHS drug tariffs, a 28 pack of 75mg clopidogrel tablets costs £1.01, or 3.6p each. A comparable pack of 75mg aspirin tablets cost 69p or 2.5p each.
The authors said that further research on the cost-effectiveness of clopidogrel, as well as broader population studies, was needed to support changes in treatment standards.