Calcium Density of Coronary Artery Plaque and Risk of Incident Cardiovascular Events

Study Questions:

What are the associations of coronary artery calcium (CAC) volume and CAC density to incident cardiovascular disease (CVD) events?

Methods:

Data from MESA (the Multi-Ethnic Study of Atherosclerosis), a multicenter, prospective, observational study conducted at six US field centers, were used for the present analysis. Men and women from four race/ethnicity groups (non-Hispanic white, African American, Hispanic, and Chinese) who were between the ages of 45-84 years, free of known CVD at baseline, had CAC >0 on their baseline computed tomography (CT), and were followed up through October 2010, were included in the present study. The primary outcome of interest was incident coronary heart disease (CHD) and all CVD events.

Results:

A total of 3,398 adults were included in the study. During follow-up (median 7.6 years), a total of 265 CVD events occurred (175 CHD and 90 CVD). With both natural logarithm CAC (InCAC) volume and CAC density scores in the same multivariable model, the InCAC volume score showed an independent association with incident CHD, with a hazard ratio (HR) of 1.81 (95% confidence interval [CI], 1.47-2.23) per standard deviation (SD) (SD, 1.6) increase, absolute risk increase 6.1 per 1,000 person-years, and for CVD, an HR of 1.68 (95% CI, 1.42-1.98) per SD increase, absolute risk increase 7.9 per 1,000 person-years. In contrast, the CAC density score showed an independent inverse association, with an HR of 0.73 (95% CI, 0.58-0.91) per SD (SD, 0.7) increase for CHD, absolute risk decrease 5.5 per 1,000 person-years, and an HR of 0.71 (95% CI, 0.60-0.85) per SD increase for CVD, absolute risk decrease 8.2 per 1,000 person years. Area under the receiver operating characteristic curve analyses showed significantly improved risk prediction with the addition of the density score to a model containing the volume score for both CHD and CVD. In the intermediate CVD risk group, the area under the curve for CVD increased from 0.53 (95% CI, 0.48-0.59) to 0.59 (95% CI, 0.54-0.64), p = 0.02.

Conclusions:

The investigators concluded that CAC volume was positively and independently associated with CHD and CVD risk. At any level of CAC volume, CAC density was inversely and significantly associated with CHD and CVD risk. The role of CAC density should be considered when evaluating current CAC scoring systems.

Perspective:

These data suggest the examination of both CAC volume and CAC density when using CT scans to evaluate CAC in association with risk for future CV events.

Clinical Topics: Diabetes and Cardiometabolic Disease, Dyslipidemia, Noninvasive Imaging, Computed Tomography, Nuclear Imaging

Keywords: Coronary Artery Disease, Follow-Up Studies, Plaque, Atherosclerotic, Tomography, X-Ray Computed, European Continental Ancestry Group, Calcinosis, Risk Factors, Hispanic Americans, Calcium, Metabolic Syndrome X, Incidence, Dyslipidemias, Cardiovascular Diseases, Confidence Intervals, ROC Curve, Coronary Vessels


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