A coronary calcium scan looks for calcium within atherosclerotic plaque in the arteries that supply the heart.
Finding no coronary calcium is generally reassuring. But it does not always mean that atherosclerosis is completely absent.
This may be particularly relevant in people with diabetes.
In the Miami Heart Study, researchers examined adults with diabetes who had no cardiovascular symptoms. Among those with no detectable coronary calcium, 30% still had coronary plaque when their arteries were examined with a more detailed CT scan.
Significant narrowing of a coronary artery was much less common. It was found in 3% of this group.
Why can this happen?
Atherosclerotic plaque does not always contain calcium. A more detailed CT examination can detect plaque that has not yet become calcified and therefore may not appear on a calcium scan.
The study does not mean that everyone with diabetes and no coronary calcium needs additional CT imaging.
It does show why a calcium score should be interpreted together with diabetes, other cardiovascular risk factors and the overall clinical assessment.
