Contrast-enhanced image of the right coronary artery is displayed (A) with cross sections perpendicular to the vessel centerline at baseline (B1, B2, and B3) and 2-year follow-up (C1, C2, and C3). Cross sections were coregistered by use of the distance from the right coronary ostium. B1 and C1 demonstrate no plaque at baseline and no plaque at follow-up; B2 and C2 demonstrate no plaque at baseline and noncalcified plaque at follow-up; B3 and C3 demonstrate noncalcified plaque at baseline and noncalcified plaque at follow-up with the development of luminal obstruction (stenosis).

Progression of coronary atherosclerotic burden expressed as a change in the percentage of cross sections containing plaque between baseline and follow-up as detected by 64-slice coronary computed tomography stratified by plaque composition. Among 69 subjects, the mean number of cross sections containing any plaque increased by 12.7% (16.5 ± 25.3 vs. 18.6 ± 25.5, p = 0.01) during a period of 24 ± 3 months. Stratification by plaque composition revealed a significant 41.9% increase in noncalcified plaque (3.1 ± 5.8 vs. 4.4 ± 7.0 cross sections containing noncalcified plaque, p = 0.04) but no significant increase in calcified plaque (13.3 ± 23.1 vs. 14.2 ± 22.0 cross sections containing calcified plaque, p = 0.2).

Scatter plot demonstrates the comparison of absolute plaque progression in a subset of 34 vessels as determined by the semiquantitative score by the use of cross sections and plaque volume measurements. Plaque volume (in mm³) was measured by the use of automated software (SUREPlaque, Vitrea 2, Vital Images) and defined as any pixels with an attenuation between +1,300 and –100 HU within the area between outer vessel boundary and inner luminal boundary. Pearson coefficient of r = 0.75, p < 0.0001 indicated a robust correlation between absolute change in number of cross sections containing plaque and absolute change of plaque volume as expressed as a partial regression line (solid line) plus 95% confidence interval (dotted line) in the plot.

Estimated effect sizes of covariates in univariable longitudinal regression models for mean plaque progression over the course of 24 ± 3 months. The forest plot displays estimated effect sizes of regression coefficients with 95% confidence intervals (x-axis). Covariates associated with a significant increase in plaque at 2 years were male sex, age as a continuous (cont.) and categorical variable, hypertension, hyperlipidemia, history of coronary artery disease (CAD), presence of baseline plaque, number of cardiovascular risk factors (CVRF), and the Framingham risk score (FRS) as a continuous variable (cont). *Years of age, as compared to patients younger than 45 years; **number of positive cardiovascular risk factors (hypertension, hyperlipidemia, diabetes, smoking, and family history of coronary artery disease, as compared to patients with no CVRF); ***FRS at baseline, as compared to subjects with FRS <4. BMI = body mass index.

Estimated effect sizes of covariates in longitudinal regression models adjusted for age, sex, and the follow-up time interval. The forest plot displays estimated effect sizes of regression coefficients with 95% confidence intervals (x-axis). Covariates associated with a significant increase in plaque at 2 years were smoking, the presence of baseline plaque, and number of cardiovascular risk factors as a continuous (cont.) variable. *Years of age, as compared to patients younger than 45 years; **number of positive cardiovascular risk factors (hypertension, hyperlipidemia, diabetes, smoking, and family history of coronary artery disease, as compared to patients with no CVRF). Abbreviations as in Figure 4.