Background: The determinants of coronary artery calcium (CAC) progression are not well understood. Prior studies have shown a limited relationship between CAC progression and traditional coronary risk factors. We hypothesized that the extent of non-calcified atherosclerosis detected using carotid intima-media thickness (CIMT) would predict progression of calcified atherosclerosis.
Methods: One hundred and eighty healthy male participants (mean age 47.9) with CAC from the Prospective Army Coronary Calcium (PACC) project volunteered to undergo a second EBCT scan, risk factor assessment, lab testing, and CIMT assessment 4.2+/-1.3 years after their original scan. All results were independently examined, blinded to baseline data. A change in CAC score >or=15% per year was defined as clinically significant progression.
Results: CAC progression occurred in 60.2%. Compared to participants without progression, those with progression had higher triglycerides, LDL and total cholesterol and Framingham risk scores, but similar blood pressure, HDL cholesterol, blood glucose, C-reactive protein, fibrinogen, and body mass index. CIMT was significantly higher among those with versus without CAC progression (0.660 mm versus 0.603 mm; P=0.001). Each quintile of increasing CIMT was independently associated with a 35% increase in the odds of CAC progression (P=0.01), after controlling for the Framingham risk score and C-reactive protein.
Conclusion: Among middle-aged men with coronary calcium, increasing extent of non-calcified atherosclerosis is strongly associated with coronary artery calcium progression over 4 years.