The make-up of plaque, which clogs arteries and can result in stroke or heart attack could provide an accurate method of assessing risk in patients, a study has found.
The study, conducted by researchers at the University of Virginia Health System, found that the greater the amount of calcium present in the plaque, the less risk the patient faces of suffering a heart attack or stroke.
It was previously thought that the amount of plaque alone determined the patient's risk.
The study found that patients exhibiting plaque that is more than 45 per cent calcified had a low risk of having symptoms of stroke.
Dr Christopher Kramer, a member of the study team, said: "We found that it's the proportion, rather than the per cent blockage, of calcified plaque that is associated with stability in patients with narrowed arteries."
The findings could lead to a change in clinical practice, away from measure how much plaque there is inside arteries towards testing the calcification of the plaque.
The findings could also enable doctors to make more accurate decisions about when surgery is necessary.