CCTA acquisition and analysis. As previously described, CCTA was performed using a 64-detector row computed tomography (CT) scanner (Brilliance 64; Philips Medical Systems, Best) and the images were transferred to an offline 3-dimensional workstation. CCTA images were independently analysed for CAC and CAP 6. The CAC score (CACS) was measured using the Agatston scoring system 8. CAP was defined as the presence of any clearly discernible atherosclerotic plaque lesion >1 mm 2 that could be discriminated from the coronary artery in ≥2 independent image planes 9. The segment stenosis score (SSS) was used as a measure of the overall CAP burden 10. According to the modified American Heart Association 15-segment criteria 11 , each segment was graded from 0 to 2: 0, no CAP; 1, CAP with maximal diameter stenosis <50%; and 2, CAP with maximal diameter stenosis ≥50%. The scores of all 15 segments were summed to yield a SSS ranging from 0-30. CAC and CAP progression were defined as increase in the CACS and SSS, respectively, on follow-up CCTA compared to that on baseline CCTA. The CAC progression rate was calculated as the annualised difference between the square root of the baseline CACS and the square root of the follow-up CACS to minimise the effect of interscan variability 12,13. The CAP progression rate was calculated as the annualised difference between the baseline and follow-up SSS. Clinical follow-up. Medical records were reviewed to assess the occurrence of cardiac death, nonfatal myocardial infarction, unstable angina, and revascularisation.