When to order a coronary calcium scan for coronary artery disease (CAD) diagnosis?

From the Guidelines

A coronary calcium scan should be ordered for asymptomatic adults aged 40-75 years with a calculated 10-year atherosclerotic cardiovascular disease (ASCVD) risk of 5-20% to guide preventive therapy decisions. This recommendation is based on the most recent and highest quality study, which suggests that a coronary calcium scan is most appropriate for individuals at intermediate risk for cardiovascular disease who would benefit from additional risk stratification 1. The test is particularly useful for patients who are reluctant to begin statins despite recommendations, as a high calcium score may improve adherence to medication and lifestyle changes.

Key Considerations

• The test is not recommended for low-risk individuals (10-year risk <5%), those already known to have coronary artery disease, or those with a clear indication for statin therapy.
• A score of zero indicates very low cardiovascular risk, while scores above 100 suggest significant atherosclerosis and higher risk.
• The radiation exposure is relatively low (about 1 mSv), and the test does not require contrast agents, making it safer than other cardiac imaging procedures.

Evidence-Based Recommendations

• The Multi-Ethnic Study of Atherosclerosis (MESA) and other studies have shown that a coronary calcium scan can predict coronary heart disease and cardiovascular events in asymptomatic individuals 1.
• A study by Mitchell et al. found that a calcium score of >100 was associated with a higher risk of myocardial infarction, stroke, and major adverse cardiovascular events (MACE) 1.
• The Coronary Artery Risk Development in Young Adults (CARDIA) study found that a coronary calcium scan can identify individuals at high risk for coronary heart disease events and cardiovascular events, even in younger adults 1.

Clinical Implications

• The use of coronary calcium scans can help guide preventive therapy decisions, such as the initiation of statin therapy, in individuals at intermediate risk for cardiovascular disease.
• A high calcium score may improve adherence to medication and lifestyle changes, which can help reduce the risk of cardiovascular events.
• The test can be used to monitor the progression of atherosclerosis and adjust treatment plans accordingly.

From the Research

Coronary Calcium Scan for CAD Diagnosis

When to order a coronary calcium scan for coronary artery disease (CAD) diagnosis is a crucial decision that depends on various factors, including the patient's risk level and medical history.

• The decision to order a coronary calcium scan should be based on the patient's individual risk factors and medical history, as recommended by current guidelines 2, 3.
• Coronary artery calcium testing is not recommended for universal screening, particularly in patients at very low or high predicted risk for ASCVD, where its yield and utility for altering clinical decisions are limited 2.
• The use of CAC testing appears to be optimal when used in selected patients who are at intermediate or borderline risk of ASCVD as a sequential decision aid after initial quantitative risk assessment and consideration of individual patient risk-enhancing factors 2, 4.

Patient Selection

The following patient groups may benefit from coronary calcium scanning:

• Patients at intermediate risk of ASCVD, where the result of the CAC test can be helpful to clarify whether the patient's true risk is high enough to justify initiation of primary prevention medications 2, 3.
• Asymptomatic patients with LDL cholesterol levels <160 mg/dL, where the addition of CAC to traditional risk factors improves risk classification 5.
• Low-intermediate risk symptomatic patients with suspected coronary artery disease, where CAC testing may play a role in assessing atherosclerotic plaque burden and predicting cardiovascular outcomes 6.

Interpretation of CAC Results

The results of the CAC test can be interpreted as follows:

• A zero score confers a very low risk of death, <1% at 10 years 3.
• CAC=1-100 indicates low risk, <10% 3.
• CAC=101-400 indicates intermediate risk, 10-20% 3.
• CAC >400 indicates high risk, >20% 3.

Management Recommendations

Based on the CAC score, the following management recommendations can be made:

• Optimal diet and lifestyle measures are encouraged in all risk groups and form the basis of primary prevention strategies 3.
• Patients with moderately-high or high risk based on CAC score are recommended to receive preventative medical therapy such as aspirin and statins 3.
• Aspirin and statins are generally not recommended in patients with CAC <100 3.