The Coronary Artery Calcium (CAC) Test is a specialized computed tomography (CT) scan used to detect calcified plaque in the coronary arteries. Calcification is a marker of atherosclerosis (plaque buildup), which can narrow the arteries and increase the risk of heart attack. Here’s a detailed overview of what the test is, how it’s performed, and how its results are interpreted.
What Is a Coronary Artery Calcium (CAC) Test?
- Purpose: The primary goal of the CAC test is to quantify the amount of calcium in the walls of the coronary arteries. Calcium deposits in these arteries reflect the presence of atherosclerotic plaque, even before significant narrowing (or symptoms) occurs. A higher calcium score suggests a higher risk for coronary artery disease (CAD) and future cardiovascular events.
- Who It’s For: This test is especially useful in individuals with intermediate risk of heart disease or those who are uncertain about starting preventive therapies like statins. It is typically not recommended for patients who are already at high risk (or have known coronary artery disease) or for those with a very low risk profile unless there is a strong family history of premature heart disease.
How Is the Test Performed?
- Patient Preparation:
- No special preparation is usually required.
- Patients are advised to wear comfortable clothing and may be asked to remove metal objects that could interfere with the imaging.
- During the Scan:
- The patient lies on a CT scanner table.
- Electrodes are placed on the chest to monitor the heart’s electrical activity (EKG) during the scan. The EKG helps the computer capture images at the optimal time during the cardiac cycle, when motion is minimal.
- The scanner takes detailed X-ray images of the heart in a matter of minutes. Patients are often asked to hold their breath for short intervals during the scan to ensure clear images.
- Radiation Exposure:
- The CAC scan involves exposure to a small amount of radiation—comparable to that of a mammogram. Although the radiation dose is low, repeated scans are generally avoided to minimize cumulative exposure.
Interpreting the Results
- Calcium Score: The results are usually reported as a calcium score, which quantifies the amount of calcified plaque present. Scores are typically grouped into ranges:
- 0: No detectable plaque, suggesting low risk.
- 1–99: Mild calcification; early atherosclerosis may be present.
- 100–399: Moderate calcification; increased risk and likely plaque burden.
- 400 or more: Extensive calcification; high risk for future cardiac events.
- Clinical Decision Making:
- Risk Stratification: The calcium score helps physicians more accurately assess a person’s risk for a heart attack or coronary events.
- Treatment Guidance: A higher score might prompt preventive measures, such as initiating or intensifying treatment with statins, low-dose aspirin, or lifestyle modifications. Conversely, a score of 0 can be reassuring and may guide the focus toward maintaining healthy habits rather than aggressive intervention2.
Benefits and Limitations
- Benefits:
- Noninvasive, relatively quick, and simple to perform.
- Provides additional information beyond traditional risk factors.
- Can motivate patients to adopt lifestyle changes or adhere to preventive medications if they see measurable evidence of calcification.
- Limitations:
- It does not detect soft, non-calcified plaque, which can also be dangerous.
- The test may not be necessary in patients with a clearly high or low risk for coronary artery disease.
- Insurance coverage varies, and out-of-pocket costs can range from approximately $100 to $400.
Advantages of CAC Tests
There are several advantages of CAC imaging compared to invasive coronary angiography.
- Minimal to no patient preparation is required. Patients do not need an intravenous (IV) catheter, intra-arterial line, beta blockers, or nitroglycerin.
- Iodinated contrast isn’t used.
- The patient doesn’t need to fast or hold medications prior to the procedure.
- Quick and efficient, CAC can be obtained on any CT scanner that can perform ECG gating, where data is acquired during a specific phase of the cardiac cycle.
- There is a low radiation dose; CAC scans use a radiation dose comparable to a screening mammogram.
Summary of CAC-Score
| CALCIUM SCORE | PRESENCE of CAD (coronary artery disease) |
|---|---|
| O | No sign of CAD |
| 1-10 | Minimal signs of CAD |
| 11-100 | Mild signs of CAD |
| 101-400 | Moderate signs of CAD |
| 401 and higher | Extensive signs of CAD |
It is important to note that CAC scans may not be covered by insurance. However, it serves as an additional tool that provides valuable information regarding ASCVD risk and helps providers and their patients make important decisions about risk reduction and treatment strategies. I will discuss CAC testing with my primary care provider at my next annual visit and I now feel better informed to talk about this type of screening with my patients, family, and friends.
Reducing the Risk of Coronary Artery Calcification
You can reduce your risk of coronary artery calcification by preventing and treating conditions that contribute to it, including:
- Diabetes
- Abnormal cholesterol levels
- High blood pressure
- Kidney disease
More generally, you can prevent or slow the progression of coronary artery disease and calcification by:
- Limiting cholesterol, fat, and salt in your diet
- Not smoking or quitting smoking
- Avoiding alcohol
- Managing your weight
REFERENCES
- Campbell, K., Harber, A., Jennings, J., & Smiley, L. (2024). CT calcium score testing for early detection of coronary artery disease. The Nurse practitioner, 49(2), 6–9. https://doi.org/10.1097/01.NPR.0000000000000140
- Schade DS, et al. A simplified approach to reducing cardiovascular risk. The Journal of Clinical Endocrinology & Metabolism. 2019; doi:10.1210/jc.2018-02509.
- Kramer, C.M. & Villines, T.C. (2022). Coronary artery calcium scoring (CAC): Overview and clinical utilization. UpToDate. https://www.uptodate.com/contents/coronary-artery-calcium-scoring-cac-overview-and-clinical-utilization
- Grundy SM, et al. 2018 A guideline on the management of blood cholesterol: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2019; doi:10.1161/CIR.0000000000000625.
- Orringer, C. E., Blaha, M. J., Blankstein, R., Budoff, M. J., Goldberg, R. B., Gill, E. A., Maki, K. C., Mehta, L., & Jacobson, T. A. (2021). The National Lipid Association scientific statement on coronary artery calcium scoring to guide preventive strategies for ASCVD risk reduction. Journal of clinical lipidology, 15(1), 33–60. https://doi.org/10.1016/j.jacl.2020.12.005
Stories are the threads that bind us; through them, we understand each other, grow, and heal.
JOHN NOORD
Connect with “Nurses Lab Editorial Team”
I hope you found this information helpful. Do you have any questions or comments? Kindly write in comments section. Subscribe the Blog with your email so you can stay updated on upcoming events and the latest articles.
