Coronary Calcium Score: Understanding the Heart Scan for Cardiac Risk

A comprehensive guide to coronary calcium scoring, the noninvasive scan that can reveal hidden risks of heart disease even before symptoms appear.

By Medha deb

Created on Sep 25, 2025

A comprehensive guide to coronary calcium scoring, the noninvasive scan that can reveal hidden risks of heart disease even before symptoms appear.

The coronary calcium score (also called coronary artery calcium, or CAC, scoring) is an advanced, noninvasive imaging test that can help reveal your risk of heart disease—even before symptoms appear. This guide will explain what the coronary calcium test is, why it matters, how it’s done, the meaning behind the results, and what steps you can take based on your score.

What Is a Coronary Calcium Score?

A coronary calcium score measures the amount of calcified plaque in your coronary arteries—the blood vessels supplying your heart with oxygen-rich blood. This calcified material is a marker of atherosclerosis, a process where
fatty deposits accumulate and harden inside the artery walls. Over time, these deposits can restrict blood flow, raise blood pressure, and increase the risk of heart attacks and strokes.

The scan is performed using a special type of CT (computed tomography) that captures detailed images of your arteries. The more calcium the scan detects, the higher your risk of developing coronary artery disease or experiencing a cardiac event, such as a heart attack.

Other names for the test include:

Coronary artery calcium scan (CAC scan)
Cardiac CT for calcium scoring
Heart scan

Why Is Coronary Artery Calcium Important?

While calcium is essential for strong bones and teeth, its presence in coronary arteries is a warning sign. Healthy arteries do not contain any significant calcium deposits. The buildup indicates that plaque is forming, which can lead to stiff, narrowed, or blocked arteries—a key mechanism underlying coronary artery disease (CAD).

Calcium in arteries is usually a consequence of long-term plaque and inflammation.
People with no signs of calcium in these arteries have a lower risk of future heart attacks, even if they have other risk factors.
High levels of coronary calcium are linked to a greater risk of heart disease and cardiac events, sometimes regardless of outward symptoms.

Who Should Consider a Coronary Calcium Scan?

The coronary calcium scan is most useful for certain groups of people. It helps clarify the risk for those who are uncertain about whether they should start or increase preventive measures for heart disease.

People aged 40 or older with intermediate risk factors for heart disease, such as modest elevations in cholesterol or blood pressure, family history of heart disease, diabetes, or obesity.
Individuals without symptoms of heart disease but with multiple risk factors that make their risk calculation unclear.
People who are debating whether to begin cholesterol-lowering therapy (statins) and need more information about their personalized risk.

Note: The CAC scan is not typically recommended for people under age 40 with no risk factors, or for those with known heart disease or prior heart attacks, as it adds little to the management plan.

How Does the Test Work?

The coronary calcium scan is quick, painless, and noninvasive. It relies on a CT scanner that uses X-rays to produce cross-sectional images of the heart.

Procedure Steps

You will lie on a table that slides into the CT scanner.
Sticky patches (electrodes) are attached to your chest to monitor your heart rate.
You may be asked to hold your breath for a few seconds while the scanner takes pictures.
The entire test usually takes less than 10 minutes, with no needles or injections required.

There is a small amount of radiation exposure—comparable to a standard chest X-ray or slightly higher—but the test is considered very safe for most adults. Results can often be available the same day.

Interpreting Your Coronary Calcium Score

The results of your heart scan will usually be given as an Agatston score, which quantifies the amount of calcium in your coronary arteries. It is possible to also receive a percentile score, showing how your result compares to others of the same age and sex.

Agatston Score	CAD Risk Interpretation
0	No evidence of CAD; very low risk of heart attack in the next 2-5 years
1-10	Minimal signs of CAD; very low to low risk
11-100	Mild signs of CAD; low to moderate risk; possible early plaque buildup
101-400	Moderate levels of calcium; moderate to high risk; significant atherosclerosis may be present
401 and higher	Extensive calcium; high risk; high likelihood of blocked arteries and recommendation to seek treatment

The higher the score, the greater the amount of calcified plaque in your arteries and the greater your risk for a heart event.

A score of zero means your risk of heart attack is very low in the next several years.
A score of 1–100 shows you have some plaque; consider preventive steps.
101–400 indicates you have moderate plaque, raising your risk and likely leading your doctor to recommend more aggressive preventive actions.
A score of over 400 means high risk, more advanced plaque, and a higher chance of blockages in the arteries. Treatment and closer medical follow-up are likely necessary.

Coronary Calcium Score and Risk Stratification

In many cases, a coronary calcium scan can help clarify how aggressively a patient (and their healthcare team) should work to reduce cardiovascular risk.

If you have no plaque (score of 0), your absolute risk is among the lowest—even if you have diabetes, obesity, or other risk factors.
If you have a high score, your risk is elevated, even if there are no outward symptoms or known history of heart disease.
Compared to traditional risk calculators (using cholesterol, blood pressure, age, etc.), CAC scoring may more accurately pinpoint those at risk who would benefit from lifestyle changes or medication.

What Are the Benefits and Limitations?

Benefits

Noninvasive and quick: No injections, sedation, or surgery are required. The scan takes only a few minutes.
Early detection: The test can uncover heart disease risk in patients who show no symptoms.
Personalized risk assessment: Offers individualized risk insight beyond standard lab results.
Better decision-making: Helps patients and physicians decide whether to start cholesterol medications or intensify other preventive efforts.

Limitations

Radiation exposure: Involves a small but real dose of radiation, so repeated testing is not generally recommended unless clinically justified.
Does not detect soft plaques: The scan only finds hard, calcified plaque, not soft or newly formed plaques.
May not be needed for everyone: Not ideal for younger adults or those with very high or very low baseline risk.
Insurance coverage may vary: Not all health insurance plans cover the test as routine screening, so out-of-pocket costs could apply.

Who Should Not Get a CAC Scan?

Individuals who already have a diagnosed coronary artery disease, have a history of heart attack, or have stents/bypass surgery—these individuals do not benefit from the scan for risk prediction.
Those with a very low pretest risk (under age 40, no risk factors) or very high pretest risk (very high cholesterol, multiple risk factors, or symptoms of heart disease) are usually managed based on clinical findings.
Pregnant women, due to the small amount of radiation exposure.

What Happens After You Get Your Results?

Your healthcare provider will interpret your results in the context of your full health picture and risk profile.

For a score of 0, aggressive preventive therapy may not be needed, although maintaining a healthy lifestyle remains important.
Low or mild scores (1–100) may lead to advice for intensified lifestyle modification.
Moderate or high scores (101 and above) typically result in recommendations for statins or other cholesterol medications, tighter control of blood pressure, and more rigorous follow-up.

Lifestyle steps are crucial at any score, with more urgent medical intervention as the score increases.

Lifestyle Recommendations After the Scan

Quit smoking and avoid secondhand smoke.
Eat a heart-healthy diet: focus on fruits, vegetables, whole grains, healthy fats, and lean proteins.
Exercise regularly—aim for at least 150 minutes of moderate aerobic activity weekly.
Keep cholesterol, blood pressure, and blood sugar in healthy ranges.
Work closely with your healthcare provider to assess the need for medications such as statins, blood pressure medicines, or antiplatelet therapy.

Frequently Asked Questions (FAQs)

Q: What is a “normal” coronary calcium score?

A: The only truly “normal” score is 0, meaning no detectable calcium in the coronary arteries. Any score higher than 0 means there is some degree of plaque buildup.

Q: Can you reduce your coronary calcium score?

A: Once calcium is present, it typically cannot be “removed” from artery walls. However, lifestyle and medication can lower your overall heart attack risk and slow the progression of calcification.

Q: How often should you have the scan?

A: For most people, a single scan is usually enough to guide future preventive strategies. Repeat scans are rarely needed unless your risk changes significantly or your doctor recommends another scan for a specific reason.

Q: Is the scan covered by insurance?

A: Coverage varies by region and insurance plan. Some insurers may not consider it routine and may require a doctor’s order with documentation of specific risk factors.

Q: What if my score is high and I feel healthy?

A: Many people with high coronary calcium scores have never had symptoms. The scan is valuable because it can reveal “silent” risk and prompt actions to prevent a future event.

Key Takeaways

The coronary calcium score is a powerful tool for revealing hidden heart disease risk before symptoms start.
It uses a simple, noninvasive CT scan to detect and quantify calcium in the coronary arteries.
A score of 0 means low risk; higher scores call for more intensive prevention and sometimes medication.
The test is best for people with uncertain or intermediate risk—not for those with diagnosed heart disease or very low/high risk.
Discuss with your doctor whether this test fits your needs and use any results to guide practical steps for living a heart-healthy life.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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