Iron buildup may be a suitable marker of cardiac risk as it is much more prevalent in the kind of plaque in the heart artery which is more likely to promote an attack - and possibly sudden death.

A team of researchers has found that Dual Energy Computed Tomography (DECT) and 3D computerised tomography (CT) micro-scans can detect excess iron in plaque, according to a Mayo Clinic statement.

It opens the way to a scanning device that might be able to non-invasively detect dangerous plaque formations in patients.

"We know that 70 percent of heart attacks are caused by unstable plaque, so what we really need for our patients is a way to identify the plaque that turns evil and puts them at jeopardy," says cardiologist Birgit Kantor, who led the study at Mayo in the US.

"The scans we use now just show narrowing of heart arteries from plaque buildup but that doesn't tell us if the plaque inside those vessels walls is imminently dangerous."

"We think it is possible, based on these findings, to use iron as a natural marker for risk," she says.

Kantor predicts that probably five to 10 years will pass before novel diagnostic scanners to identify these plaques become available in cardiology clinics.

The findings were presented at the American Heart Association's Scientific Sessions 2010 in Chicago.