You're just as likely to suffer a fatal heart attack when your arteries aren't blocked, a major new study has found-so putting a question-mark over the cholesterol/blocked artery theory of heart disease.
People with clear arteries where blood is flowing freely still face a 44 per cent increased risk of a major heart attack, and one that could even be fatal.
Their risk was similar to people whose arteries were obstructed by LDL cholesterol, say researchers from the University of Colorado's School of Medicine.
They tracked 40,872 older people who had their heart and arteries checked by angiogram, and were categorised either as normal, non-obstructive CAD (coronary artery disease) and obstructive CAD.
Yet, within a year, the rate of heart attack and death was similar in both the CAD groups, so the obstruction of arteries was only one factor, the researchers say.
The message seems to be that people with non-obstructive CAD shouldn't be complacent; they should give up smoking if they are smokers, eat healthy diets, exercise and lose weight.
(Source: American Heart Association Quality of Care and Outcomes research 2014 scientific sessions)