European clinical guidelines on how to treat a major form of heart disease are under review following a BBC Newsnight investigation.
Europe's professional body for heart surgeons has withdrawn support for the
sagame guidelines, saying it was "a matter of serious concern" that some patients may have had the wrong advice.
Guidelines recommended both stents and heart surgery for low-risk patients.
But trial data leaked to Newsnight raises doubts about this conclusion.
Thousands of people in the UK and hundreds of thousands worldwide will be treated for left main coronary artery disease each year. This is a narrowing of one of the main arteries in the heart.
The guidelines on how to treat it were largely based on a three-year trial to compare whether heart surgery or stents - a tiny tube inserted into a blocked blood vessel to keep it open - was more effective.
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The trial called Excel started in 2010 and was sponsored by big US stent maker, Abbott.
It was led by eminent US doctor
บาคาร่า Gregg Stone and aimed to recruit 2,000 patients. Half were given stents and the other half open heart surgery.
Success of the treatments was measured by adding together the number of patients that had heart attacks, strokes, or had died.
The research team used an unusual definition of a heart attack, but had said that they would also publish data for the more common "Universal" definition of a heart attack alongside it. There is debate around which is a better measure and the investigators stand by their choice.
In 2016, the results of the trial for patients three years after their treatments were published in the prestigious New England Journal of Medicine. The article concluded stents and heart surgery were equally effective for people with left main coronary artery disease.
But researchers had failed to publish data for the common, "Universal" definition of a heart attack.
Newsnight has seen that unpublished data and it shows that under the universal definition, patients in the trial that had received stents had 80% more heart attacks than those who had open heart surgery.
The lead researchers on the trial have told Newsnight that this is "fake information". But Newsnight has spoken to experts who say they believe the data is credible.
