Objectives The aim of this study was to examine the long-term prognosis in asymptomatic individuals with a coronary artery calcium (CAC) score of 0 and its associated warranty period. Background Emerging evidence supports a CAC score of 0 as a favorable cardiovascular short-to intermediate-term prognostic factor. Methods A total of 9,715 individuals undergoing CAC imaging were stratified by age, Framingham risk score (FRS), and National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) categories and followed for a mean of 14.6 years (range 12.9 to 16.8 years). Cox regression, area under the receiver-operating characteristic curve, and net reclassification information were used to assess all-cause mortality, discrimination, and reclassification of a CAC score of 0 compared with the FRS and NCEP ATP III, respectively. A warranty period was pre-defined as <1% annual mortality rate. Vascular age was estimated by linear regression. Results In 4,864 individuals with a baseline CAC score of 0 (mean age, 52.1 ± 10.8 years; 57.9% male), 229 deaths occurred. The warranty period of a CAC score of 0 was almost 15 years for individuals at low and intermediate risk with no significant differences regarding age and sex. A CAC score of 0 was associated with a vascular age of 1, 10, 20, and 30 years less than the chronological age of individuals between 50 and 59, 60 and 69, 70 and 79, and 80 years of age and older, respectively. The CAC score was the strongest predictor of death (hazard ratio: 2.67, 95% confidence interval: 2.29 to 3.11) that enabled discrimination and consistent reclassification beyond the FRS (area under the receiver-operating characteristic curve: 0.71 vs. 0.64, p < 0.001) and NCEP ATP III (area under the receiver-operating characteristic curve: 0.72 vs. 0.64, p < 0.001). Conclusions A CAC score of 0 confers a 15-year warranty period against mortality in individuals at low to intermediate risk that is unaffected by age or sex. Furthermore, in individuals considered at high risk by clinical risk scores, a CAC score of 0 confers better survival than in individuals at low to intermediate risk but with any CAC score.
Bibliographical noteFunding Information:
This study was supported in part by grants from the National Institutes of Health (R01HL115150 and R01HL118019) and also funded in part by a generous gift from the Dalio Institute of Cardiovascular Imaging and the Michael Wolk Foundation. Dr. Truong is supported by NIH grants K23HL098370 and L30HL093896 and has received grant support from St. Jude Medical, American College of Radiology Imaging Network, and Duke Clinical Research Institute. Dr. Chang is supported by Leading Foreign Research Institute Recruitment Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT, & Future Planning (MSIP) grant 2012027176. Dr. Min has served on the medical advisory boards of GE Healthcare, Arineta, AstraZeneca, and Bristol-Myers Squibb; on the Speakers Bureau of GE Healthcare; received research support from GE Healthcare, Vital Images, and Phillips Healthcare; serves as a consultant to AstraZeneca, Abbott Vascular, HeartFlow, NeoGraft Technologies, MyoKardia, and CardioDx; and is supported by grants NIH/NHLBI-R01 HL111141, NIH/NHLBI-R01 HL115150, NIH/NHLBI-R01 HL118019, NIH/NHLBI-U01 HL105907, and a grant from the Qatar National Research Foundation NPRP09-370-3-089. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. Sherif Nagueh, MD, served as Guest Editor for this paper.
© 2015 American College of Cardiology Foundation.
- computed tomography
- coronary artery calcium
- warranty period