Author + information
- Received October 1, 2008
- Revision received March 10, 2009
- Accepted March 24, 2009
- Published online June 1, 2009.
- Michael Blaha, MD, MPH⁎,
- Matthew J. Budoff, MD†,
- Leslee J. Shaw, PhD‡,
- Faisal Khosa, MD§,
- John A. Rumberger, MD, PhD∥,
- Daniel Berman, MD¶,
- Tracy Callister, MD#,
- Paolo Raggi, MD‡,
- Roger S. Blumenthal, MD⁎ and
- Khurram Nasir, MD, MPH⁎⁎,⁎ ()
Reprint requests and correspondence:
Dr. Khurram Nasir, Division of Cardiology, Johns Hopkins University, Baltimore, Maryland 21287
Objectives We sought to quantify the mortality rates associated with absent and low positive (CAC 1 to 10) coronary artery calcium (CAC).
Background There is increasing interest in the absence of CAC as a “negative” cardiovascular risk factor. However, published event rates for individuals with no CAC vary, likely owing to differences in baseline risk, follow-up period, and outcome ascertainment. The prognostic significance of low CAC (CAC 1 to 10) is not well described.
Methods Annualized all-cause mortality rates were assessed in 44,052 consecutive asymptomatic patients referred for CAC testing. Mean follow-up of the cohort was 5.6 ± 2.6 years (range 1 to 13 years).
Results A total of 19,898 patients (45%) had no CAC on screening electron beam tomography, whereas 5,388 (12%) had low levels of CAC (CAC 1 to 10), and 18,766 (43%) had CAC >10. There were 104 deaths in those with no CAC (0.52%), 58 deaths in those with CAC 1 to 10 (1.06%), and 739 deaths in those with CAC >10 (3.96%). Annualized all-cause mortality rates for CAC = 0, CAC 1 to 10, and CAC >10 were 0.87, 1.92, and 7.48 deaths/1,000 person-years, respectively. The hazard ratio (HR) for all-cause mortality among CAC 1 to 10 versus CAC = 0 after adjustment for traditional risk factors was 1.99 (95% confidence interval [CI]: 1.44 to 2.75). Smoking (HR: 3.97, 95% CI: 2.75 to 5.41) and diabetes mellitus (HR: 3.36, 95% CI: 2.09 to 5.41) were associated with few events observed in CAC = 0 group.
Conclusions In appropriately selected asymptomatic patients, the absence of CAC predicts excellent survival with 10-year event rates of approximately 1%. A finding of 0 CAC might be used as a rationale to emphasize lifestyle therapies rather than pharmacotherapy and to forgo repeated imaging studies. Individuals with low CAC score (CAC 1 to 10) are at increased risk above individuals with a 0 score and could be considered a distinct risk group by physicians and investigators.
Drs. Budoff and Shaw are on the Speakers' Bureau of GE Healthcare. Dr H. William Strauss served as Guest Editor for this paper.
- Received October 1, 2008.
- Revision received March 10, 2009.
- Accepted March 24, 2009.
- American College of Cardiology Foundation