What Is a Coronary Calcium Scan?

Medically Reviewed by James Beckerman, MD, FACC on November 06, 2022
4 min read

You’ve probably heard how good calcium is for your bones. But did you know calcium might be a big clue to your heart health, too?

Your doctor can use what’s called a coronary calcium scan to get a clearer picture of your risk for a heart attack.

This heart scan uses a special type of X-ray called a CT scan. It takes pictures of your arteries, the vessels that carry blood away from your heart, to check for calcium.

You may hear this scan called by several different names:

  • Coronary calcium scan
  • Calcium scan test
  • Cardiac CT for calcium scoring

The calcium that the scan is looking for is part of plaque. This is not the stuff you get on your teeth, but a different kind found in your arteries. It’s made partly of fat and calcium, and it’s not good for your heart.

Plaque is waxy at first, and it builds up slowly. But over time, it can harden. You may hear doctors call this “calcified” plaque. It’s a problem for two reasons.

First, hard plaque in your arteries is like a clog in a pipe. It slows your blood flow. That means some parts of your body don’t get enough of the oxygen they need. If plaque collects in your heart’s arteries, you may feel chest pain and discomfort, called angina.

Second, that plaque can break open, which can lead to a blood clot. That could cause a heart attack.

The coronary calcium scan tells you how much calcified plaque is in your heart’s arteries. You and your doctor can take the results and decide if you need to make any changes to your medicine or lifestyle.

The coronary calcium scan isn’t for everyone.

Your body is exposed to radiation during the test. Because of that, you want to get this scan only if it can tell you something useful.

First, you need to know how likely you are to get heart disease. Your doctor has ways to figure this out based on:

Heart scans make the most sense if you have a moderate, or medium, chance of heart disease based on these things.

If you have only a low chance, the test isn’t likely to show any calcium. If you have a high chance, you won’t learn anything more that can help you. In both of these cases, you’d be exposed to extra radiation for no good reason.

But if you have a medium chance, you may be able to take steps to avoid heart disease based on the scan results.

Insurance usually doesn’t cover this kind of scan. So it’s a good idea to check on that before you get the test. The cost is usually around $100 to $400.

You will visit a hospital or clinic that has a CT scanner. Your doctor may ask you to avoid caffeine or smoking for up to 4 hours before the test.

For the scan, you’ll wear a hospital gown, so you’ll need to take off your clothing and jewelry from the waist up.

The person who runs the scanner will put a few sticky patches on your chest. These patches connect to what’s called an EKG machine, which helps the person running the scan know exactly when to take pictures of your heart.

If you get nervous in closed or tight spaces, you can get medicine that will help keep you calm. You may also get medicine to slow your heart so they can take better pictures.

During the test, you’ll lie on your back on a table that slowly moves into the CT scanner. The scanner is a hollow tube, so it’s like sliding into a tunnel. Your head stays out of the tube at all times.

The person running the scan stands on the other side of a glass wall and uses a speaker to talk to you. It usually takes 10 to 15 minutes. Once you’re done, you can go about your day. You won’t get any type of dye for a coronary calcium scan.

The scan gives you a number called an Agatston score. Your doctor may get your results the same day of the test, but it can take longer.

Zero means the test didn’t find any calcium. The higher the number, the more important it is for you and your doctor to come up with a plan.

Your doctor can help you understand what your score means for you. Based on the results, you may need more tests. You might also make changes in:

  • How much exercise you get
  • What medicines you take
  • What you eat

Keep in mind that a high score doesn’t mean you’re sure to have a heart attack. But it does signal you may need to make some heart-healthy changes to your lifestyle or consider starting a new medication.