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Can coronary calcium scans help identify who will develop heart disease?

Coronary calcium scans (a type of X-ray) reveal specks of calcium in the walls of coronary arteries. The specks, showing calcifications, are an early sign of coronary heart disease (CHD) and may indicate that an individual is at increased risk for a heart attack or other heart problems before other signs and symptoms occur. A new study shows that including a coronary artery calcium score in a risk assessment for future heart disease events provides a better estimate than a standard coronary risk factors assessment.

What was the study?

The study, "Coronary artery calcium score and risk classification for coronary heart disease prediction," was funded by the National Heart, Lung, and Blood Institute (NHLBI) and published in the Journal of the American Medical Association, April 28, 2010.

  • Participants were part of the Multi-Ethnic Study of Atherosclerosis (MESA) Study. This large, NHLBI-supported multicenter, prospective cohort study is focused on finding early signs of heart and vascular disease before symptoms appear.
  • The participants were 5,878 generally healthy men and women ages 45 to 84 years. They identified themselves as white (38%), African American (28%), Hispanic (22%), or Chinese (12%).
  • Coronary calcium was assessed by chest computed tomography (CT). All scans were read at a central center.
  • Interviewers telephoned participants or a family member every 9-12 months to ask about hospital admissions, heart disease diagnoses, and deaths. Trained personnel interviewed physicians and next of kin of the participants, as well as reviewed hospital records, to verify diagnoses and events. Events were classified as myocardial infarction, death due to CHD, resuscitated cardiac arrest, definite or probable angina followed by coronary revascularization, and definite angina not followed by coronary revascularization.
  • Five-year estimated incident CHD risk was calculated with and without addition of the coronary calcium score to standard Framingham Heart Study risk scoring factors (age, sex, smoking, systolic blood pressure, use of antihypertensive medications, high-density lipoprotein and total cholesterol) and race/ethnicity.

What did the study find?

  • During 5.8 years of follow-up, 209 participants had CHD events (122 had a major event such as myocardial infarction, death from CHD, or resuscitated cardiac arrest, and 87 had angina).
  • Addition of a coronary artery calcium score to traditional risk factors significantly improved risk prediction in this group of asymptomatic individuals. The addition of a coronary artery calcium score:
    • Accurately placed 77 percent of participants into the highest or lowest risk categories, compared to 69 percent assessed with traditional risk factors alone.
    • Resulted in an additional 23 percent of participants who experienced events being reclassified as high risk.
    • Resulted in an additional 13 percent of participants who did not experience events being reclassified as low risk.
  • The study did not find that having the coronary calcium score benefitted participants, however.

What are the take-home messages?

  • Including a coronary calcium score in a risk assessment for future heart disease events provides a better estimate than a standard coronary risk factors assessment.
    • Inclusion of a coronary artery calcium score was most helpful for asymptomatic individuals at intermediate risk of heart disease–defined as those with a 3 to 10 percent chance of developing heart disease over the next five years.
    • A coronary artery calcium scan may not be an efficient screening tool among low-risk individuals.
    • It is generally accepted that patients who are at high risk should be treated regardless of their coronary artery calcium score, and as a result do not need coronary artery calcium testing for additional risk assessment.
  • Coronary artery calcium scanning, however, is not generally recommended as a screening test. The scans entail additional costs and some risks, such as exposure to small amounts of radiation. Just as important, the ability to improve prediction of risk for CHD is not known to translate into improved prevention of CHD.
  • Further research will be needed to determine whether use of coronary calcium scans improves clinical outcomes.
  • "Physicians should first consider and treat major risk factors, such as high cholesterol and high blood pressure, and address smoking in their patients, because modifying these risk factors will improve outcomes," said Diane Bild, M.D., director of the NHLBI’s Prevention and Population Sciences Program and a coauthor of the paper, in an accompanying NHLBI news release.

Where can I learn more?

  • Polonsky, T.S., et al. Coronary artery calcium score and risk classification for coronary heart disease prediction, Journal of the American Medical Association, 303(16),1610-1616, April 28, 2010.
  • Ioannidis, J.P.A. and Tzoulaki, I. What makes a good predictor? The evidence applied to coronary artery calcium score, Journal of the American Medical Association, 303(16),1646-1647, April 28, 2010.
  • Coronary Artery Calcium (CAC) reference values and Arterial Age Calculator from the Multi-Ethnic Study of Atherosclerosis (MESA) study
  • "Coronary Calcium Scans" from the NHLBI Diseases and Conditions Index (DCI)
  • Researcher Profile: Meet Dr. Stephen Rich who is studying gene variations that might lead to heart disease
  • Adding Coronary Calcium Score to Traditional Risk Factors Improves Risk Assessment for Heart Disease (news release).

Additional information on the study:

  • Study recruitment spanned from July 2000 to September 2002, and follow-up extended through May 2008.
  • MESA participants were recruited from six communities across the United States: Forsyth County, N.C., New York City, N.Y., Baltimore, Md., St. Paul, Minn., Chicago, Ill., and Los Angeles, Calif.

July 2010

Archived page, reproduced from a 2011 copy. It is reference material, not current guidance.