Test Overview
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.
Normally, the coronary arteries do not contain calcium. Calcium in the coronary
arteries is 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.
For help deciding about getting this test, see:
Heart Disease Risk: Should I Have a Coronary Calcium Scan?
Why It Is Done
Your doctor
may want you to have a coronary calcium scan if you have several risk factors
for heart disease. Or your doctor may want you to have this test if he or she thinks that results could change your treatment for heart disease.
This test might be most helpful for people who have no symptoms
but who are at medium risk for heart disease.
Medium risk means that you have a 10% to 20% chance of having a heart attack in
the next 10 years, based on your risk factors. This means that 10 to 20 out of
100 people with this level of risk will have a heart attack in the next 10
years.
To find out your risk, see the
Interactive Tool: Are You at Risk for a Heart Attack?
And talk with your doctor about your risk for heart disease.
A coronary calcium scan is not advised for routine screening for
coronary artery disease.1 This test may not tell your doctor any more about your risk for heart disease than your risk factors do.
This screening test is not for you if:
- You don't have any risk factors for heart
disease.
- You are at high risk for heart disease. (You should
already be under a doctor’s care.)
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.
You
probably will not have this test if you have had a
heart attack,
coronary artery bypass surgery (CABG), or
angioplasty. Also, the test usually is not for women
who are or might be pregnant.
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(What is a PDF document?).
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 medicine doctor,
internist,
cardiologist, or
surgeon, may also review this
test.
You will need to remove any jewelry 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.
Risks
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.
- There is a slight risk that a CT scan can interfere with implanted or external medical devices. Examples of medical devices include pacemakers, insulin pumps, defibrillators, and neurostimulators.
- You could get a high score from the test even
if your arteries are not blocked. This could lead to extra tests that you don't
need. Or it could cause you to worry when there’s no reason. But these kinds of
results are most likely to happen in people who are at low risk for heart
disease. So if you already know that you're at low risk, you shouldn't get this
test.
- Not all blocked arteries have calcium. A low test score may
make you feel safe even though you're still at risk.
Results
After you have the test, talk with your doctor
about your results. The
radiologist may discuss initial results with you right after the test.
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.
People who score between 100 and 400 or higher, and
who are at medium risk for heart disease, are more likely to have a heart
attack in the next 3 to 5 years than people who score 0.2
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.
- Smoking.
- Caffeine use.
What To Think About
- 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.
- Coronary calcium scans are not needed very
often because a physical exam and other tests can give information about your
heart. This test is not advised for routine screening for
coronary artery disease.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. Eat
better, quit smoking, and get more exercise. These are the same steps your
doctor would recommend after looking at your health history, your physical
health, and any lab tests, such as a cholesterol test. If you have
high blood pressure or
high cholesterol, talk to your doctor about your
treatment choices.
- It is possible to have
false-positive test results. This means that the test
shows a high chance of blockage 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.
- Coronary calcium scans may not be covered
by all health insurance plans.
- Coronary calcium scans may not be
available in some areas of the United States, such as in small towns.
- Sometimes doctors automatically schedule routine tests because they think that's what patients expect. But experts say that routine heart tests can be a waste of time and money. For information, see Heart Tests: When Do You Need Them?
References
Citations
- U.S. Preventive Services Task Force (2009). Using Nontraditional Risk Factors in Coronary Heart Disease Risk Assessment. Rockville, MD: Agency for Healthcare Research and Quality. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscoronaryhd.htm.
- Budoff M, et al. (2006). Assessment of coronary artery
disease by cardiac computed tomography: A scientific statement from the
American Heart Association Committee on Cardiovascular Imaging and
Intervention, Council on Cardiovascular Radiology and Intervention, and
Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation, 114(16): 1761–1791.
Other Works Consulted
- Budoff MJ, et al. (2008). Computed tomography of the
heart. In V Fuster et al., eds., Hurst's The Heart, 12th
ed., pp. 577–606. New York: McGraw-Hill Medical.
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.
- 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 (2004). Screening for coronary heart disease: Recommendation statement. Annals of Internal Medicine, 140(7): 569–572. Also available online: http://www.ahrq.gov/clinic/3rduspstf/chd/chdrs.htm.
- U.S. Preventive Services Task Force (2009). Using Nontraditional Risk Factors in Coronary Heart Disease Risk Assessment. Rockville, MD: Agency for Healthcare Research and Quality. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscoronaryhd.htm.
Credits
| By | Healthwise Staff |
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| Primary Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
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| Specialist Medical Reviewer | George Philippides, MD - Cardiology |
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| Last Revised | April 25, 2011 |
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U.S. Preventive Services Task Force (2009). Using Nontraditional Risk Factors in Coronary Heart Disease Risk Assessment. Rockville, MD: Agency for Healthcare Research and Quality. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscoronaryhd.htm.
Budoff M, et al. (2006). Assessment of coronary artery
disease by cardiac computed tomography: A scientific statement from the
American Heart Association Committee on Cardiovascular Imaging and
Intervention, Council on Cardiovascular Radiology and Intervention, and
Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation, 114(16): 1761–1791.
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