What is the Coronary Artery Calcium (CAC) score?

From the Guidelines

The Coronary Artery Calcium (CAC) score is a measure of the amount of calcium in the coronary arteries, which is a strong predictor of cardiovascular risk and can be used to guide preventive therapies.

Key Points

• The CAC score is typically measured using a non-invasive CT scan and is expressed in Agatston units 1.
• A CAC score of 0 indicates a low risk of cardiovascular events, while a score of >100 indicates a higher risk 1.
• The CAC score can be used to reclassify patients with a family history of premature CAD to a high-risk category and can even reclassify those individuals without risk factors as higher risk than those with multiple risk factors but no coronary artery calcification 1.
• A CAC score of >100 Agatston units or ≥75th percentile for age, sex, and ethnicity favors up-classification of CVD risk 1.
• The CAC score can be used to adjust the typical mortality expectation that accompanies chronological age, with a CAC score of 0 indicating a "warranty period" of very low risk for cardiovascular events 1.

CAC Score Interpretation

• CAC score of 0: indicates a low risk of cardiovascular events, with a yearly mortality rate of <1% for >15 years 1.
• CAC score of 1-100: indicates a mild risk of cardiovascular events, with a relative adjusted subhazard ratio of 2.2 for myocardial infarction 1.
• CAC score of 101-400: indicates a moderate risk of cardiovascular events, with a relative adjusted subhazard ratio of 3.8 for myocardial infarction 1.
• CAC score of >400: indicates a high risk of cardiovascular events, with a relative adjusted subhazard ratio of 5.9 for myocardial infarction 1.

From the Research

Definition of Coronary Artery Calcium (CAC) Score

• The Coronary Artery Calcium (CAC) score is an objective marker of atherosclerosis, which is used to assess the risk of coronary artery disease (CAD) 2.
• It provides direct visualization and quantification of CAC burden for risk stratification and primary prevention of cardiovascular events in an asymptomatic population 3.
• The CAC score is a measure of coronary atherosclerosis and has been created as a reliable indicator of CAD 4.

Interpretation of CAC Scores

• A CAC score of 0 is the strongest negative predictive factor for cardiovascular disease (CVD), and a 0 score can successfully de-risk a patient 3.
• Higher CAC scores correlate with worse cardiovascular prognostic outcomes 3.
• The CAC score can be used to estimate coronary heart disease risk, and combining information from the CAC score with information from conventional risk factors can change assessment of coronary heart disease risk to an extent that may be clinically important 5.

Clinical Use of CAC Scores

• CAC scoring is recommended for individuals with intermediate 10-year atherosclerotic cardiovascular disease (ASCVD) risk and selective populations with borderline ASCVD risk 3.
• The CAC score can be used to inform personalized shared decision making in the primary prevention of atherosclerotic cardiovascular disease 6.
• The CAC score can help strategize early interventions and improve the prophylaxis and treatment of a wider range of apparently healthy patients 3.