Researchers have identified a positive and independent association between coronary artery calcium volume and risk for CHD and CVD.
It is known that coronary artery calcium (CAC) measured by CT has strong predictive value for incident CVD, and previous studies have suggested that denser calcified plaques are associated with decreased CVD risk. However, few studies have compared which specific measures of CAC are most predictive and whether incorporating CAC density into the scoring system would be beneficial.
Michael H. Criqui, MD, MPH, of the department of family and preventive medicine at University of California, San Diego, and colleagues analyzed data from 3,398 men and women who participated in the MESA study. All participants were aged 45 to 85 years, free of known CVD and had a CAC >0 at baseline enrollment (2000-2002). Follow-up occurred through October 2010.
The two primary endpoints were hard CHD (MI, resuscitated cardiac arrest or CHD death) and hard CVD (hard CHD, stroke or stroke death). The researchers also analyzed independent associations between the two primary endpoints with CAC volume and density scores.
During follow-up, 175 CHD and 90 CVD events occurred.
Results showed an independent association between CAC volume and incident CHD; the HR was 1.81 (95% CI, 1.47-2.23) per standard deviation (SD=1.6) increase and the absolute risk increase was 6.1 per 1,000 person-years. There was also an independent association between CAC volume and incident CVD; the HR was 1.68 (95% CI, 1.42-1.98) per SD increase and the absolute risk increase was 7.9 per 1,000 person-years.
When the researchers measured CAC density, they found an independent inverse association. For CHD, the HR was 0.73 (95% CI, 0.58-0.91) per SD (SD=0.7) and the absolute risk decrease was 5.5 per 1,000 person-years. For CVD, the HR was 0.71 (95% CI, 0.6-0.85) per SD increase and the absolute risk decrease was 8.2 per 1,000 person-years.
CHD and CVD rates increased monotonically across the four quartiles of CAC volume score. Consequently, the CAC density score was lower in the first quartile of volume, but similar in the top three quartiles. CAC density was inversely related to CVD events at a given CAC volume, and CAC volume was more predictive when adjusted for CAC density, the researchers found.
“The role of CAC density should be considered when evaluating current CAC scoring systems,” Criqui and colleagues concluded.
Disclosure: See the study for a full list of the researchers’ relevant financial disclosures.