A coronary calcium scan looks for calcium within atherosclerotic plaque in the arteries that supply the heart.
If no calcium is detected, the result is called a coronary calcium score of zero. This is generally a reassuring finding.
But does it mean that the heart arteries are completely free of atherosclerosis?
Not always.
The Miami Heart Study examined 2 359 adults aged 40–65 years who had no cardiovascular symptoms. Researchers first measured calcium in their heart arteries. They also used a more detailed CT examination to look directly for coronary plaque.
Among people with a calcium score of zero, 16% still had coronary plaque.
There is a simple reason for this. A calcium scan detects plaque that has become calcified. Atherosclerotic plaque can also be present before calcium becomes detectable.
At the same time, the study provides important reassurance. Significant narrowing of the heart arteries and plaques with high-risk features were uncommon when the calcium score was zero.
A calcium score of zero is therefore valuable information. But it does not mean that coronary atherosclerosis is completely absent.
