Absence of Coronary Artery Calcification and All-Cause Mortality
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*,
Khurram Nasir, MD, MPH**,*
* Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, Maryland
Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, California
Division of Cardiology, Emory University, Atlanta, Georgia
Department of Radiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
|| Princeton Longevity Center, Princeton, New Jersey
¶ Department of Imaging and Medicine, Cedars-Sinai Medical Center, Los Angeles, California
# Tennessee Heart and Vascular Center, Hendersonville, Tennessee
** Ciccarone Preventive Cardiology Center, Johns Hopkins University, School of Medicine, Baltimore, Maryland and the Department of Internal Medicine, Boston Medical Center, Boston, Massachusetts
* Reprint requests and correspondence: Dr. Khurram Nasir, Division of Cardiology, Johns Hopkins University, Baltimore, Maryland 21287 (Email: knasir1{at}jhmi.edu).
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.
Key Words: coronary artery calcium • electron beam tomography • mortality risk
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Abbreviations and Acronyms
| | CAC = coronary artery calcium | | CHD = coronary heart disease | | EBT = electron beam tomography |
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