Interpretation of the Coronary Artery Calcium Score in Combination With Conventional Cardiovascular Risk Factors: The Multi-Ethnic Study of Atherosclerosis (MESA)

Sep 24, 2013
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Authors:
Pletcher MJ, Sibley CT, Pignone M, et al.
Citation:
Circulation 2013;128:1076-1084.
Summary By:
Melvyn Rubenfire, MD, FACC

Study Questions:

How does one use the coronary artery calcium (CAC) score, combined with conventional coronary heart disease (CHD) risk factors, to improve coronary risk assessment?

Methods:

CAC scores and CHD risk factor measurements and conventional risk factors were obtained from 6,757 black, Chinese, Hispanic, and white men and women, ages 45-84 years, in the Multi-Ethnic Study of Atherosclerosis (MESA).

Results:

CAC was associated with age, sex, race/ethnicity, and all conventional CHD risk factors. Multivariable models using these factors predicted the presence of CAC (C statistic = 0.789) and degree of elevation (16% of variation explained), and can be used to update a “pretest” CHD risk estimate, such as the 10-year Framingham Risk Score, which is based on an individual’s conventional risk factors. In scenarios in which a high CAC score is expected, a moderately elevated CAC score of 50 is reassuring (e.g., reducing risk from 10% to 6% in a healthy older white man), but when a low/zero CAC score is expected, even with identical pretest CHD risk, the same CAC score of 50 may be alarmingly high (e.g., increasing risk from 10% to 20% in a middle-aged black woman with multiple risk factors). Both the magnitude and direction of the shift in risk varied markedly with pretest CHD risk and with the pattern of risk factors.

Conclusions:

Knowledge of what CAC score to expect for an individual patient, based on their conventional risk factors, may help clinicians decide when to order a CAC test and how to interpret the results.

Perspective:

The publication has a risk calculator sheet that can be used to assign a risk based on conventional risk factors which give a pretest likelihood, with CAC score giving the post-test. I assume it will be on the web and an app soon. Of course the risk estimate is per 100 patients with those parameters, and does not provide the true risk for an individual.

Keywords: Ethnic Groups, Coronary Artery Disease, Atherosclerosis, European Continental Ancestry Group, Calcinosis, Risk Factors, Coronary Vessels, Risk Assessment, African Continental Ancestry Group


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