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Question 5#

Concerning coronary artery calcification, which one of the following statements is false?

a. The coronary calcium score is a good independent predictor of future cardiac events
b. A normal coronary calcium score excludes flow-limiting coronary disease
c. A high coronary calcium score will decrease the negative predictive value of coronary CT angiography
d. Coronary calcium results in partial volume artefact
e. The coronary calcium score correlates with total plaque burden

Correct Answer is B

Comment:

Coronary artery calcium scoring (CACS) was initially investigated using electron beam CT. Several scoring systems were devised, the most widely used being the Agatston score. This combines assessment of the volume and the density or mass of coronary calcium. Studies have shown that total coronary calcium is a good independent predictor of future cardiac events. The presence of coronary calcium confirms the presence of atheroma and correlates with the total plaque burden but does not always correlate with the location of a stenosis.

A coronary calcium score of zero is associated with a <1% risk of future coronary events. However, flow-limiting non-calcified atheroma is clearly not excluded and therefore clinical correlation is necessary.

A high coronary calcium score will decrease the negative predictive value and overall accuracy of a coronary CT angiogram, as calcium results in partial volume or blooming artefact in which dense structures can appear larger than their true size. This impairs visualization of the adjacent coronary lumen and can lead to an over- or underestimation of coronary stenosis when compared with catheter angiography.

Therefore CACS can be used as an important adjunct to the Framingham risk assessment and thereby significantly increase or decrease this risk.