An aspirin a day keeps a heart attack at bay? Not for some people, suggests a new study, which found that the drug does not prevent heart attacks in patients with undiagnosed or asymptomatic heart disease.
Researcher Gerry Fowkes, of the Wilson Unit for Prevention of Peripheral Vascular Diseases in Edinburgh, found that the use of aspirin to prevent a heart attack in people with asymptomatic disease "cannot be supported."
The research, known as the Aspirin for Asymptomatic Atherosclerosis (AAA) study, included more than 3,300 subjects who were given either 100 mg of aspirin a day or a placebo.
Fowkes found little difference between the two groups in the rates of heart attack, stroke or death after about eight years of follow-up.
The findings were presented Sunday at the European Society of Cardiology Congress in Barcelona.
Professor Peter Weissberg, medical director of the British Heart Foundation -- which partly funded the research -- said the findings support the group's current guidelines on the use of aspirin for heart-attack prevention.
"We know that patients with symptoms of artery disease, such as angina, heart attack or stroke, can reduce their risk of further problems by taking a small dose of aspirin each day," Weissberg said in a statement.
"The findings of this study agree with our current advice that people who do not have symptomatic or diagnosed artery or heart disease should not take aspirin, because the risks of bleeding may outweigh the benefits."
Patients who have been diagnosed with atherosclerosis (where plaque builds up and clogs the arteries) and have previously suffered a heart attack have long been prescribed drugs such as aspirin that prevent blood clots, which can trigger heart attacks and strokes.
However, in addition to the British Heart Foundation warning about the risk of internal bleeding, a study published in the medical journal the Lancet earlier this year sounded the same alarm.
The study, led by Professor Colin Baigent of the University of Oxford, included more than 100,000 subjects. It found that aspirin was linked to a one-fifth reduction in non-fatal heart attacks in patients with no history of heart disease.
But it also found that the risk of internal bleeding was raised by about one third.
In patients who are given aspirin to prevent a second heart attack, the benefits of taking aspirin outweigh the risks, the study concluded.
However, Baigent said, "We don't have good evidence that, for healthy people, the benefits of long-term aspirin exceed the risks by an appropriate margin."
