CORONARY ARTERY CALCIUM DENSITY AND CARDIOVASCULAR DISEASE EVENTS
Michael H. Criqui, M.D., University of California, San Diego, La Jolla, CA, USA
Background: Coronary artery calcium (CAC) measured by computed tomography (CT) has strong predictive value for incident cardiovascular disease (CVD) events. The standard CAC score is the Agatston, which is weighted upward for greater calcium density. However, some data suggest increased plaque calcium density may be protective for CVD.
Methods - We analyzed the independent associations of CAC volume and CAC density with incident hard coronary heart disease (CHD) and all hard CVD events in a multiethnic population of 3398 men and women who had at least some CAC on their baseline CT scan.
Results - During a median of 7.6 years of follow-up, there were 175 CHD events and an additional 90 other CVD events. With both CAC volume and density scores in the same multivariable model, the CAC volume score showed a strong independent association with incident CHD and all CVD, with hazard ratios of 1.77 (p<.0001) and 1.62 (p<.0001) respectively per standard deviation increase. Conversely, the density score showed a strong and independent inverse association, with hazard ratios of 0.73 for CHD (p=.006) and 0.72 for CVD (p=.0003) per standard deviation increase. Receiver Operating Characteristic curve analyses showed significantly improved risk prediction after addition of the density score to the multivariable model.
Conclusions - Increased density of CAC was associated with lower risk of incident CHD and CVD at any given volume of CAC. CAC scoring systems should be modified to include density as a protective factor, which will improve CVD risk prediction.