A coronary calcium scan is a type of CT scan of the heart. It measures the amount of calcium in the walls of the coronary arteries and can detect the early signs of heart disease. A score of zero is typical, and the higher the score, the more likely a person is to have heart disease.

Calcium is a natural part of the human body, but it can sometimes appear in places where it is unwanted. For example, when a waxy substance called plaque builds up in the arteries, it can calcify over time.

When it calcifies, the plaque hardens and begins to block the blood flow through a person’s arteries. This creates inflammation and can cause a heart attack. Other times, pieces of plaque can break off and cause a clot, which can result in blood flow stopping, leading to a heart attack.

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A coronary calcium scan is a low dose CT scan of the heart. It produces images that doctors use to measure how much calcium-containing plaque is in a person’s arteries. This helps them determine if a person is likely to develop heart disease or have a heart attack.

Determining this means healthcare professionals can put together a plan of action to minimize the risks.

Other names that people may use to refer to a coronary calcium scan include:

  • coronary artery calcium scan
  • calcium scan procedure
  • cardiac CT for calcium scoring

People who should have this test include those with the following risk factors:

Coronary calcium scans are not always useful. For example, if a person has a very low risk of heart disease, the test is unlikely to show anything.

If a person has a very high risk of heart disease, they are so likely to have a high score on the coronary calcium scan that there is little point in having one done.

People who already have heart disease do not need to have this scan, as it will only confirm what they already know, and their doctors will not discover anything new.

For those reasons, it may not always be worth having a coronary calcium scan. People should speak with a healthcare professional about whether the scan is right for them.

As with all CT scans, there is a small risk associated with the radiation used in the scan. However, the amount of radiation is minimal. It is around the same amount as an average person receives in a year.

If someone is taking a statin medication for their cholesterol, they should not have a coronary calcium scan. This animal study suggests statins can affect calcium scores.

Doctors may also advise people who are pregnant to wait until after their pregnancy to have this scan due to the risks to the fetus. If the need for the scan is urgent, healthcare professionals will take extra protective steps to minimize the risk.

Typically, there is nothing a person needs to do to prepare for a coronary calcium scan. Doctors may request a person avoid caffeine the day of the procedure. If anything else is necessary, the doctor will tell the person in advance of the scan.

People will need to make sure they are not wearing any metal objects, and may have to wear a hospital gown to help ensure this.

During the scan, a person will lay flat on their back on a table that will move into a circular machine. Once inside, they will need to place their arms above their head.

Next, the radiography team will apply monitors to the person’s chest and ask them to stay as still as possible and briefly hold their breath.

The scan typically takes 10–15 minutes. During this time, the team will take many X-rays to form a 3D image of a person’s heart.

A cardiologist or radiologist will interpret the results of the scan.

Typically, people will receive an explanation of the preliminary results of the scan directly after the procedure.

After this, the results go to a person’s doctor within a few days. The person can then discuss their results with the doctor further.

A person’s coronary calcium score allows healthcare professionals to check a person’s risk of coronary heart disease, coronary artery disease (CAD), and heart attack. They can use this score to determine what further course of action, if any, is necessary to look after a person’s heart.

Formal coronary calcium scan scoring has existed since 1990. Most healthcare professionals use a scoring system called the Agatston score or the volume method.

  • A score of zero means that a person has no plaque in their arteries. It means they have a low risk of heart disease or a heart attack.
  • A score of 1–10 suggests a small amount of plaque that may need monitoring and possibly lifestyle changes to ensure it does not worsen.
  • A score of 11–100 means the person may require some medical treatment to lower the risk of heart disease.
  • A score between 101–400 indicates that there is some plaque blocking the arteries and that a person has a higher risk of heart attack and needs medical treatment.
  • A score above 400 will require additional testing and immediate treatment.
Coronary calcium scan scorePlaqueRiskNext steps
0none presentlow risk of CAD or heart attackno treatment required
1–10minimal amounts of plaque presentlow risk of CAD or heart attacklifestyle changes to help prevent the score from increasing
11–100small amounts of plaque presentmoderate risk of CAD or heart attackmay need lifestyle changes and sometimes medication
101–400moderate amounts of plaque that may be blocking arteriesmedium to high risk of CAD or heart attackmedical treatments, lifestyle changes, and follow-up testing
Over 400extensive amounts of plaque that is likely to be blocking the arterieshigh risk of CAD or a heart attackimmediate further testing and treatment to help prevent heart attack

Typically, insurance will not cover the cost of a coronary calcium scan. In 2015, the mean cost of the procedure was $100. While prices may have increased since then, people always have the opportunity to shop around for the best price.

There will likely be places nearby that can perform a coronary calcium scan.

People can discuss with a doctor if a coronary calcium scan is suitable for them, and the doctor can refer them to a scan team if necessary.

Having a high coronary calcium scan score does not mean that a person is definitely going to have a heart attack, but it does mean that their risk is higher than someone with a low score.

A coronary calcium scan means that doctors are able to predict a person’s chance of developing heart disease. This means they can plan the next steps, which may include lifestyle changes, medications, or further testing.