When to order a coronary artery calcium (CAC) score?

From the Guidelines

A coronary calcium score should be ordered for individuals at intermediate risk for cardiovascular disease, specifically those with a calculated 10-year atherosclerotic cardiovascular disease risk of 5-20%, to guide preventive therapy decisions, as recommended by the 2019 ACC/AHA guideline 1. This includes asymptomatic adults aged 40-75, particularly when there is uncertainty about initiating statin therapy. The test is most useful for those with borderline risk factors, family history of premature coronary disease, or when traditional risk calculators may underestimate risk. Some key points to consider when ordering a coronary calcium score include:

• It should not be ordered for low-risk individuals (10-year risk <5%), those already known to have coronary artery disease, or those with very high risk who already have clear indications for aggressive preventive therapy.
• The calcium score quantifies coronary artery calcification, which directly correlates with atherosclerotic plaque burden and future cardiovascular event risk.
• A score of zero indicates very low risk, while scores above 100 suggest increased risk and may warrant more aggressive preventive measures including statins, aspirin, and lifestyle modifications.
• The test involves minimal radiation exposure and doesn't require contrast, making it relatively safe and accessible for appropriate candidates. Recent studies, such as the 2021 ACR Appropriateness Criteria 1, have further supported the use of coronary calcium scoring for risk stratification in asymptomatic adults, demonstrating its ability to predict future mortality and major cardiac events beyond conventional risk factor–based scores alone. However, the most recent and highest quality study, the 2019 ACC/AHA guideline 1, provides the strongest evidence for the use of coronary calcium scoring in intermediate-risk individuals, and its recommendations should be prioritized in clinical practice.

From the Research

Indications for Coronary Calcium Score

The decision to order a coronary calcium score is guided by several factors, including:

• The presence of intermediate risk of atherosclerotic cardiovascular disease (ASCVD) 2
• The presence of risk-enhancing factors such as family history of premature ASCVD, premature menopause, metabolic syndrome, chronic kidney disease, lipid and inflammatory biomarkers, and low ankle-brachial index 2
• The need for further risk assessment and personalized management in the primary prevention of atherosclerotic cardiovascular disease 3

Patient Selection

Coronary calcium scoring is particularly useful in:

• Asymptomatic individuals for planning primary prevention interventions such as statins and aspirin 4
• Patients with stable coronary artery disease (CAD) to improve CAD risk prediction 5
• Individuals with an intermediate risk of ASCVD to guide the allocation of statin therapy 2

Clinical Applications

The coronary calcium score has several clinical applications, including:

• Risk classification in patients with chest pain 5
• Guiding the initiation of statin therapy in individuals with an intermediate risk of ASCVD 2
• Informing the safe delay or avoidance of certain preventive therapies in individuals with a CAC score of zero 3
• Predicting coronary heart disease (CHD) and cardiovascular disease (CVD) mortality in statin users and non-users 6

Key Considerations

When ordering a coronary calcium score, it is essential to consider:

• The prognostic value of a CAC score of zero, which may be used to de-risk individuals and inform the safe delay or avoidance of certain preventive therapies 3
• The potential interaction between CAC score and statin use for the prediction of CHD and CVD mortality 6
• The role of CAC scoring in informing personalized shared decision making in the primary prevention of atherosclerotic cardiovascular disease 3