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). Coronary calcium scans are also called cardiac calcium scoring.
The coronary arteries supply blood to the heart. 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 do not 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 might be pregnant or are pregnant. This test is not done on pregnant women.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .
How It Is Done
A coronary calcium scan is usually done by a radiology technologist. The pictures are usually interpreted by a radiologist. Other doctors, such as a family doctor, internist, cardiologist, or surgeon, may also review this test.
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 do not have zippers or snaps.
Small metal discs 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.
If your heart rate is 90 beats per minute or higher, you may be given medicine to slow your heart rate.
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. You will be able to talk with the technologist through a two-way intercom.
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 slight chance of developing cancer from having a coronary calcium scan. The chance is higher in people who have many radiation tests. If you are concerned about this risk, talk to your doctor about the amount of radiation this test may give you and confirm that the test is needed.
- 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. Any score over 100 means that you are likely to have heart disease. The higher your score, the greater your chance of having a heart attack.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Having a fast heart rate.
- Caffeine use.
What To Think About
- Most people do not get a coronary calcium scan. The test is not used for routine screening for coronary artery disease. Your doctor may want you to have the test if other tests are unclear about your risk for coronary artery disease.footnote 1
- If your coronary calcium scan shows that you have a high chance of having heart disease, you can take steps to lower your chance. Talk with your doctor about what steps you can take.
- Coronary calcium scans may not be covered by all provincial health plans.
- Coronary calcium scans may not be available in some areas of Canada.
- Anderson T, et al. (2012). 2012 update of the Canadian Cardiovascular Society guidelines for the diagnosis and treatment of dyslipidemia for the prevention of cardiovascular disease in the adult. Canadian Journal of Cardiology, 29(2): 151–167.
- 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.
Other Works Consulted
- Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.
- Daubert MA, et al. (2011). Computed tomography of the heart. In V Fuster et al., eds., Hurst's The Heart, 13th ed., vol. 1, pp. 599–630. New York: McGraw-Hill.
- Goff DC Jr, et al. (2013). 2013 ACC/AHA guideline on the assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437741.48606.98. Accessed November 22, 2013.
- Greenland P, et al. (2007). ACCF/AHA 2007 clinical expert consensus document on coronary artery calcium scoring by computed tomography in global cardiovascular risk assessment and in evaluation of patients with chest pain. Circulation, 115(3): 402–426.
- Greenland P, et al. (2010). 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Journal of the American College of Cardiology, 56(25): e50–e103.
- Kim KP, et al. (2009). Coronary artery calcification screening: Estimated radiation dose and cancer risk. Archives of Internal Medicine, 169(13): 1188–1194.
- Taylor AJ, et al. (2010). ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 – Appropriate use criteria for cardiac computed tomography: A Report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance. Journal of the American College of Cardiology, 56(22): 1864–1894.
- U.S. Preventive Services Task Force (2009). Using nontraditional risk factors in coronary heart disease risk assessment. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscoronaryhd.htm.
Current as of: December 16, 2019
Author: Healthwise Staff
Medical Review: E. Gregory Thompson MD - Internal Medicine
Brian D. O'Brien MD - Internal Medicine
Adam Husney MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology
Current as of: December 16, 2019