Variation in atherosclerotic plaque composition according to increasing coronary artery calcium scores on computed tomography angiography

Increasing coronary artery calcium scores (CACS) are independently associated with cardiac events. Recent advents in coronary computed tomography angiography (CCTA) have allowed us to better characterize individual plaque. Currently, it is unknown if higher CACS are likely to be associated with more calcified or mixed and heterogeneous plaque burden on CCTA. The study population consisted of 1,043 South Korean asymptomatic subjects (49 ± 10 years, 62% men) who underwent CCTA (64-slice MDCT). Plaques were classified on contrast-enhanced CCTA as non-calcified, mixed, and calcified on a per-segment basis according to the modified American Heart Association classification. The majority of the study participants had no coronary calcification (n = 866, 83%), whereas CACS> 0 was observed in 177 participants (17%). Only 40 (5%) participants in absence of CACS had exclusively non-calcified plaque, whereas 10 (1.2%) had significant coronary artery disease. With increasing CACS, study participants were more likely to have exclusively mixed or combination atherosclerotic plaques (P = 0.001). Among individuals with CACS 1-10, the prevalence of at least two coronary segments with mixed plaques was 4%, increasing up to 18 and 41% with CACS of 11-100 and >100. The respective prevalence of ≥2 coronary segments (calcified plaques) with increasing CACS were 6%, 16 and 26% (P = 0.01) and of non-calcified plaques were 6%, 6 and 11% (P = 0.71). In multivariable adjusted analyses, those with CACS >100 were 7.17 times (95% CI: 1.36-37.68) more likely to have ≥2 coronary segments with calcified plaque comparing with CACS 1-10. On the other hand the respective risk was higher for presence of ≥2 segments with mixed plaques (odds ratio: 15.81, 95% CI: 3.14-79.58). Absence of CAC is associated with a negligible presence of any atherosclerotic disease as detected by CCTA in asymptomatic population. A higher CACS is more likely to be associated with heterogeneous coronary plaque (combination of calcified, non-calcified, and mixed plaques), and appears to be more strongly associated with a higher burden of mixed plaque.