What is coronary artery calcium scoring (CACS)?

Updated: Jul 24, 2019
  • Author: J Bayne Selby, Jr, MD; Chief Editor: Eugene C Lin, MD  more...
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Answer

Coronary artery calcium scoring (CACS) is a measure of coronary artery calcification detected on EBCT or helical CT. It is a marker of the atherosclerotic plaque burden and is an independent predictor of future myocardial infarction and mortality. CACS provides incremental risk information beyond traditional risk calculators. [5, 7, 2]

To calculate a CAC score, the original Agatston method involved defining a calcified lesion as a density ≥130 Hounsfield units and an area ≥3 pixels. A score was assigned to each lesion (the product of density and area), and the total score was reached by adding up each of the calcified lesion scores. A semiautomated method is now commonly utilized, following the same principles. [5]

Cardiovascular risk stratification using calcium scoring has been widely studied, and standard categories according to cardiovascular prognosis and total mortality are as follows [8] :

CAC=0:  very low risk of death (< 1% at 10 years)

CAC=1-100:  low risk of death (< 10% at 10 years)

CAC=101-400: intermediate risk of death (10-20% at 10 years)

CAC=101-400 and >75th percentile for age, sex, and ethnicity: moderately high risk of death (15-20% at 10 years)

CAC >400:  high risk of death (>20% at 10 years

In a large study of asymptomatic patients who underwent a coronary artery calcium (CAC) CT scan, a high CAC score predicted a higher risk of death during a mean follow-up of 12 years. Compared with individuals with a CAC of 0, those with a CAC >400 had a 1.8-fold to 3.2-fold increased risk of all-cause death and a 3.1 to 5.1-fold increased risk of CVD death. [9]


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