Heart disease remains the leading cause of death worldwide, with coronary artery disease (CAD) being one of the most common forms. Early detection plays a crucial role in preventing major cardiac events, and one of the most effective tools for assessing heart disease risk is the coronary artery calcium test (CAC). This imaging test measures the amount of calcium buildup in the coronary arteries, helping physicians evaluate a patient’s risk of developing serious cardiovascular conditions.

By providing a direct measure of plaque accumulation, the CAC test offers valuable insight into the progression of atherosclerosis. However, while the test can help refine treatment strategies, it has limitations, including cost, radiation exposure, and its inability to detect non-calcified plaque. Understanding when and how to use CAC testing is essential for patients and healthcare providers seeking to optimize cardiovascular risk management.

Understanding the Coronary Artery Calcium Test

How the CAC Test Works

The CAC test is a specialized computed tomography (CT) scan that detects and quantifies calcium deposits in the coronary arteries. These calcium deposits indicate the presence of atherosclerosis, a condition in which fatty deposits and cholesterol accumulate along artery walls, restricting blood flow to the heart. Unlike cholesterol tests or stress tests, which assess risk factors indirectly, the CAC test provides a direct measurement of plaque buildup, offering a clearer picture of cardiovascular health.

The test is non-invasive and requires no contrast dye, making it a relatively simple procedure. Patients lie on a scanning table while a CT scanner captures detailed images of the heart. The entire process typically takes 10 to 15 minutes and involves low-dose radiation exposure, similar to a mammogram. Results are then analyzed to generate a CAC score, which helps classify a patient’s risk level for coronary artery disease.

CAC Score Categories and Clinical Interpretation

The CAC test results are presented as a numerical score, known as the Agatston score, which reflects the extent of calcified plaque in the coronary arteries. The score falls into different categories, each associated with varying levels of heart disease risk:

• CAC Score of 0: A score of zero indicates no detectable coronary calcium, suggesting a low likelihood of significant atherosclerosis. Individuals with this score have a very low risk of a heart attack within the next five years, though it does not rule out other forms of heart disease or the presence of non-calcified plaques.
• CAC Score of 1–99: A low-to-moderate score indicates some level of plaque buildup, but the risk of a major cardiac event remains relatively low. Individuals in this category may benefit from lifestyle modifications such as improved diet, regular exercise, and smoking cessation to slow disease progression.
• CAC Score of 100–399: A moderate-to-high score suggests a significant amount of calcified plaque, correlating with an elevated risk of heart disease. Physicians often recommend a more aggressive approach to risk management, including cholesterol-lowering medications like statins, blood pressure control, and enhanced lifestyle interventions.
• CAC Score of 400 or Higher: A high score indicates extensive plaque buildup and a substantial risk of a heart attack or other cardiovascular events. Individuals in this category require intensive medical intervention, possibly including medication, further testing, and close monitoring by a cardiologist.

By stratifying patients into different risk categories, the CAC score helps refine treatment plans and guide decision-making regarding preventive therapies.

Benefits of the Coronary Artery Calcium Test

• Provides a Direct Measure of Atherosclerosis: Unlike blood tests or traditional risk calculators, which estimate cardiovascular risk based on demographic and lifestyle factors, the CAC test offers a direct assessment of plaque burden in the arteries. This makes it a more precise tool for evaluating actual disease presence.
• Enhances Risk Stratification: Many individuals have intermediate heart disease risk based on conventional assessments. The CAC test helps refine this classification, identifying those who may need early intervention despite having normal cholesterol levels or no apparent symptoms.
• Non-Invasive and Time-Efficient: The procedure does not require injections, contrast agents, or extensive preparation. It is completed within minutes, making it a convenient option for patients seeking a quick yet effective evaluation of their heart health.
• Encourages Preventive Action: Patients who see visual evidence of calcium buildup in their arteries are often more motivated to adopt healthier lifestyles. A higher CAC score may encourage adherence to prescribed treatments, such as medication, diet changes, and exercise routines.
• Guides Medication Decisions: Physicians often face uncertainty about whether to prescribe statins or aspirin therapy for individuals with borderline risk. The CAC score serves as an additional data point that helps determine whether medical treatment is necessary.

Limitations and Considerations

• Radiation Exposure: The CAC test uses a low-dose CT scan, which exposes patients to a small amount of radiation. While the exposure is minimal, repeated scans over time may increase cumulative radiation risk, making the test less suitable for younger individuals or those requiring frequent monitoring.
• Limited Usefulness in Certain Populations: The test is most valuable for individuals with intermediate or uncertain cardiovascular risk. However, it may be less useful for younger adults, women, and certain high-risk individuals, such as those with diabetes, where aggressive treatment is often recommended regardless of CAC score.
• Cost and Insurance Coverage Issues: The cost of the CAC test ranges from $50 to $500, depending on the facility. Many insurance providers do not cover it, making it an out-of-pocket expense for many patients. This lack of coverage can limit accessibility, particularly for those who would benefit most from the test.
• Potential for Incidental Findings: Because the scan captures images of the chest, it may detect unrelated abnormalities, such as lung nodules, that require further testing. While this can lead to early detection of other conditions, it may also result in unnecessary anxiety and medical expenses.

Who Should Consider a CAC Test?

• Individuals with Intermediate or Uncertain Risk: People whose traditional risk factors place them in a gray area for heart disease benefit most from CAC testing. The score provides additional clarity on whether preventive treatment is needed.
• Those with a Family History of Heart Disease: Individuals with a strong family history of heart attacks or coronary artery disease may have an elevated risk, even if their cholesterol and blood pressure levels appear normal. The CAC test helps assess their true level of risk.
• Patients Debating Medication Use: Many individuals with borderline risk struggle to decide whether they should start statins or other preventive medications. A high CAC score can justify early intervention, while a score of zero may allow for postponing treatment in favor of lifestyle modifications.
• Asymptomatic Adults Concerned About Heart Health: Some individuals without symptoms may seek proactive heart health assessments. For those with risk factors such as obesity, high cholesterol, or smoking history, the CAC test offers valuable insight into their cardiovascular status.

Conclusion

The coronary artery calcium test is a powerful tool for assessing heart disease risk, providing a direct measure of plaque buildup in the arteries. It helps refine cardiovascular risk classification, guiding treatment decisions and preventive measures. While the test is most useful for individuals with intermediate risk, it has limitations, including cost, radiation exposure, and the potential for incidental findings.

Patients considering CAC testing should consult with their healthcare providers to determine whether the test is appropriate for their situation. Regardless of CAC score, maintaining a heart-healthy lifestyle remains the most effective strategy for reducing cardiovascular disease risk.