Heart patients may be put at risk because doctors are misjudging the likelihood of a further attack, according to an international study led by the University of Edinburgh.
It looked at data taken from the Global Registry of Coronary Events that included more than 46,000 heart attack patients from 115 hospitals in 14 countries.
The findings, published in the September edition of the journal Nature Clinical Practice, contradict the assumption that patients whose arteries had been completely, instead of partially, blocked are the most at risk after discharge from hospital.
While patients with full heart attacks were more likely to have another heart attack within the first 15 days, the risk for those whose heart attack was originally considered not as severe overtook the full heart attack group after 26 days.
Professor Keith Fox, British Heart Foundation Professor of Cardiology at Edinburgh, said: "The risk for patients may be being misjudged.
"As a result, there may be some patients who should be, but are not, receiving treatments such as the placing of stents to open up the artery, drug treatments and lifestyle changes that could prevent a further heart attack from occurring."