Coronary Artery Calcium Scans

CT scanning to detect coronary artery disease

Patient having an x-ray examination

Martin Barraud / OJO Images / Getty Images

Overview

Atherosclerosis causes the smooth, elastic lining of the coronary arteries to become hard, stiff, and swollen because of plaque. These are deposits of calcium, fats, and abnormal inflammatory cells that clog the arteries and reduce blood flow. This means that if you have calcium deposits in your coronary arteries, you have at least some coronary artery disease (CAD).

For many years, healthcare providers have known that certain sophisticated computerized tomography (CT) scans can detect and measure coronary artery calcium deposits. The names given to the various kinds of cardiac CT scans can be confusing, but any CT scan used to measure coronary artery calcium is usually referred to as simply a "calcium scan."

This article explains who might be a good candidate for a calcium scan, how the test is performed, and how the score is interpreted.

Is a Calcium Scan Right for You?

If you're uncertain about whether to undergo a calcium scan, begin by assessing your risk for heart disease. And ask your healthcare provider to help you.

University of Michigan Health says that the scan is most helpful for people at medium risk for heart disease. They will get the most benefit from the scan because they can make the lifestyle changes that may be in order to lower their risk, such as eating better, exercising, losing weight, and quitting smoking. Cholesterol or blood pressure medication also might be options.

By contrast, the scan is not helpful to people who have a low or high risk of heart disease. People at high risk are presumably already under the care of a healthcare provider. You might fall into the medium-risk category if you:

  • Have a family history of heart disease
  • Have borderline high cholesterol, high blood pressure, or diabetes
  • Are overweight or live a sedentary lifestyle. Americans spend nearly eight hours per day in a sitting position, or being sedentary.

Despite these risk factors, many people find out they have heart disease only after having a heart attack. A coronary calcium scan can give you an early heads-up that you are at risk.

How the Test Is Performed

Having a calcium scan is very much like having an X-ray. It's painless, quick (taking about 15 minutes), and does not require intravenous (IV) fluids (or a needle in your arm). 

As you lie on an X-ray table, a technologist will attach wires to your chest to record an ECG and the table will slide into the scanner. You will be asked to hold your breath for a minute or so to obtain the clearest image possible.

The resulting computerized X-ray image will be examined for the telltale white spots that indicate calcium deposits in the coronary arteries. The amount of calcium is then translated into a score.

Age Plays a Role

The scan may not be right for men younger than 40 or women younger than 50 because they presumably don't have much calcium buildup in their arteries.

Interpreting a Calcium Score

The presence of plaque can be "graded" on a scale from 0 to more than 400. The scores and their meanings are as follows:

  • 0 means no plaque is present and your risk of heart attack is low.
  • 1 to 10 means that a small amount of plaque is present, you have a 10% percent chance of developing heart disease, and your risk of heart attack is low.
  • 11 to 100 means that some plaque is present. You have mild heart disease and a moderate chance of heart attack. A score in this range may prompt your healthcare provider to recommend lifestyle changes and other treatments.
  • 101 to 400 means that a moderate amount of plaque is present. You have heart disease, plaque may be blocking an artery, and your chance of having a heart attack is moderate to high. Your provider may order more tests and begin treatment in the meantime.
  • More than 400 means a large amount of plaque is present. The chance that plaque is blocking one of your arteries is more than 90% and your chance of heart attack is high. Your healthcare provider will probably order more tests and begin treatment.

It's possible to get a high score on the scan even if your arteries show no signs of heart disease. (In this case, more tests will probably be in order.) False results are most likely to occur among people who are at low risk for heart disease, which is why they should not undergo the scan in the first place.

Recap

 In general, the higher your score, the more likely you are to have heart disease.


Usage

Today's healthcare providers realize that the chief benefit of calcium scans is not to find specific areas of blockage but to identify whether a patient has CAD, and if so, to estimate its severity. This information can be very useful in deciding how aggressive to be in trying to reduce risk factors. Returning to the basics of eating better, exercising, losing weight, and quitting smoking can pay real dividends if you align your goals with conventional healthcare advice. To healthcare experts:

  • Eating better involves eating foods high in fiber, and low in saturated fats, trans fat, and cholesterol.
  • Exercising means getting at least two hours of moderate-intensity exercise every week.
  • Losing weight or maintaining a healthy weight means doing so because extra weight can put stress on the heart and blood vessels.
  • Quitting smoking is important because smoking greatly increases the risk for heart disease; quitting will lower the risk. If you don’t smoke, don’t start.

Prioritize Fruits and Vegetables

Eating plenty of fresh fruits and vegetables and fewer processed foods are other good ways to reduce your risk for heart disease.

Risks

The only real risk to a calcium scan is the exposure to radiation, which occurs with any X-ray. The amount of radiation a person receives with a calcium scan varies quite a bit depending on the equipment used.

Before you agree to a calcium scan, ask the lab how much radiation exposure you will be exposed to. A reasonable amount of radiation with a calcium scan is 1.7 mSv (millisievert), which is equivalent to about six months of naturally occurring radiation.

Check Your Policy

You may wish to check your insurance plan before scheduling a coronary artery calcium scan. Not all health plans cover it, and the fees can vary.

Summary

A coronary calcium scan uses computed tomography to check for calcium buildup on the walls of the coronary arteries. It's best suited for people who have no current symptoms of heart disease but may be at risk of getting it. These include people who have a family history of heart disease, borderline high cholesterol, high blood pressure or diabetes, or are overweight or live an inactive lifestyle. The scan results in a score ranging from 0 to more than 400. In general, the higher the number, the greater the risk for heart disease.

A Word From Verywell

The University of Maryland Medical Centers calls the coronary calcium scan "a better predictor of coronary events than cholesterol screening or other risk factor assessments." If you take the test, prepare yourself to hear some advice that may be difficult for you to embrace and be open to making the lifestyle changes that are often recommended.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. University of Michigan Health. Coronary calcium scan: Should I have this test?

  2. Johns Hopkins Medicine. Cardiac CT calcium score.

  3. Park, J. H., Moon, J. H., Kim, H. J., Kong, M. H., & Oh, Y. H. Sedentary lifestyle: Overview of updated evidence of potential health risksKorean journal of family medicine. 2020;41(6), 365–373. doi:10.4082/kjfm.20.0165.

  4. University of Maryland Medical Center. Cardiac calcium scoring.

  5. National Heart, Lung, and Blood Institute. Coronary calcium scan.

  6. Centers for Disease Control and Prevention. Prevent heart disease.

  7. RadiologyInfo.org. Radiation dose in X-ray and CT exams.

  8. Cigna. Coronary calcium scan: Should I have this test?

Additional Reading
  • Agatston AS, Janowitz WR, Hildner FJ, et al. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol 1990 Mar 15;15(4):827-32
  • Greenland, P, Bonow, RO, Brundage, BH, et al. 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: a report of the American College of Cardiology Foundation Clinical Expert Consensus Task Force (ACCF/AHA Writing Committee to Update the 2000 Expert Consensus Document on Electron Beam Computed Tomography) developed in collaboration with the Society of Atherosclerosis Imaging and Prevention and the Society of Cardiovascular Computed Tomography. J Am Coll Cardiol 2007; 49:378.
  • Radiology Exposure in X-ray Examinations. Radiologyinfo.com (American College of Radiology and Radiological Society of North America.