Calcium Density of Coronary Artery Plaque and Risk of Incident Cardiovascular Events
Do coronary artery calcium (CAC) volume and density predict incident cardiovascular disease (CVD) events?
Data for this analysis were collected as part of the MESA (Multi-Ethic Study of Atherosclerosis) study, a multicenter, prospective, observational cohort conducted at six US centers, and comprised four race/ethnicity groups including non-Hispanic whites, African-Americans, Hispanics, and Chinese. All participants were ages 45-84 years and free of known CVD at baseline. All participants had CAC greater than 0 at the time of baseline computed tomography. Follow-up was completed in October 2010. The primary outcome of interest was incident coronary heart disease (CHD) events and all CVD events.
A total of 3,398 participants (1,964 men and 1,434 women), mean age 66 years, were included in this analysis. The race/ethnicity distribution was 44% non-Hispanic white, 24% African American, 20% Hispanic, and 12% Chinese. During a median of 7.6 years of follow-up, there were 175 CHD events and an additional 90 other CVD events, for a total of 265 CVD events. With both natural log (ln) CAC volume and CAC density scores in the same multivariable model, the lnCAC 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 = 1.6) increase, and an absolute risk increase of 6.1 per 1,000 person-years. For CVD events, lnCAC volume was significantly associated with an HR of 1.68 (95% CI, 1.42-1.98) per SD increase, absolute risk increase of 7.9 per 1,000 person-years. Conversely, 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 of 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 of 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.
The investigators concluded that CAC volume was positively and independently associated with both CHD and CVD events. In contrast, CAC density (at any level of CAC volume) was inversely associated with CHD and CVD risk.
These data suggest that CAC volume is of significant clinical benefit for identifying patients in need of aggressive risk factor management.
Clinical Topics: Atherosclerotic Disease (CAD/PAD)
Keywords: Coronary Artery Disease, Follow-Up Studies, Atherosclerosis, Plaque, Atherosclerotic, Cardiovascular Diseases, Calcinosis, Risk Factors, ROC Curve, Hispanic Americans
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