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Coronary calcium scans use a special X-ray test called computed tomography (CT) to check for the buildup of calcium in plaque on the walls of the arteries of the heart (coronary arteries). This test is used to check for heart disease in an early stage and to determine how severe it is. Coronary calcium scans are also called cardiac calcium scoring.
The coronary arteries supply blood to the heart muscle. Normally, the coronary arteries do not contain calcium. Calcium in the coronary arteries may be a sign of coronary artery disease (CAD).
A CT scan takes pictures of the heart in thin sections. The pictures are recorded in a computer and can be saved for more study or printed out as photographs.
Why It Is Done
Your doctor may want you to have a coronary calcium scan if other test results are not clear about whether you should start treatment to reduce your risk of coronary artery disease.footnote 1
A coronary calcium scan is not advised for routine screening for coronary artery disease.
How To Prepare
You don't need to do anything before you have this test. But you may be asked to not smoke or not eat or drink anything that has caffeine for a few hours before your test.
Tell your doctor if you get nervous in tight spaces. You may get a medicine to help you relax. If you think you'll get this medicine, be sure you have someone to take you home.
How It Is Done
You will need to remove any jewellery that might be in the way of the X-ray picture. You may need to take off some of your clothes. If so, you will be given a gown to use during the test. For some CT scans, you may be able to wear your clothes. If so, wear loose clothes that don't have zippers or snaps.
Small pads or patches called electrodes will be put on your chest. Wires connect these to an EKG machine that records the electrical activity of your heart on paper. The EKG records when your heart is in the resting stage, which is the best time for the CT scans to be taken.
During the test, you will lie on a table connected to the CT scanner. The scanner is a large doughnut-shaped machine.
The table slides into the round opening of the machine, and the scanner moves around your body. The table will move a little every few seconds to take new pictures. You may hear clicking or buzzing sounds as the table and scanner move.
You may be asked to hold your breath for 20 to 30 seconds while pictures of your heart are taken. It is very important to hold completely still while the pictures are taken.
During the test, you are usually alone in the scanner room. But the technologist will watch you through a window and talk with you during the test.
How long the test takes
A coronary calcium scan takes about 30 minutes.
How It Feels
You won't have any pain from the X-rays during the coronary calcium scan. But the table you lie on may feel hard and the room may be cool. You may find it hard to lie in one position for a long time.
The chance of a coronary calcium scan causing a problem is small.
- There is a risk of damage to cells or tissue from being exposed to radiation, including the small amounts used in CTs, X-rays, and other medical tests. Over time, exposure to radiation may cause cancer and other health problems. But in most cases, the risk of getting cancer from being exposed to small amounts of radiation is low. It is not a reason to avoid these tests for most people.
- Plaque that is not hard (soft plaque) can't be found with a coronary calcium scan. Soft plaque is the earliest form of damage to the arteries of the heart. If you have soft plaque in your arteries, the test may give normal results, but this is a false-negative result. The buildup of soft plaque can also cause a heart attack.
- It is possible to have false-positive test results. This means that the test shows a high chance of plaque in the arteries of the heart when it is not true. People with a low chance of heart disease are most likely to have a false-positive test.
After you have the test, talk with your doctor about your results.
Your test result is a number that is your calcium score. The score can range from 0 to more than 400. The higher your score, the greater your chance of having a heart attack. The score might be helpful if you are aren't sure whether to take a statin to lower your risk of a heart attack. Your doctor will look at your calcium score as well as your age, your health, and your other test results such as your cholesterol level.footnote 1
- Anderson TJ, et al. (2016). 2016 Canadian Cardiovascular Society guidelines for the management of dyslipidemia for the prevention of cardiovascular disease in the adult. Canadian Journal of Cardiology, 32(11): 1263–1282. DOI: 10.1016/j.cjca.2016.07.510. Accessed October 20, 2018.
Current as of:
April 29, 2021
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology
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