Aspirin could be as effective as more expensive drugs for heart failure patients with a normal heart rhythm, according to researchers.
Their study on more than 2,000 patients, published in the New England Journal of Medicine, said aspirin was as effective as the commonly prescribed drug warfarin.
It said each drug had risks, but they had similar benefits overall.
However, a UK cardiologist argued the risks from warfarin were less serious.
Heart failure is a major health problem in many parts of the world. It affects 900,000 people in the UK and six million people in the US. A failing heart struggles to pump blood around the body, meaning even trivial tasks become exhausting.