Absence of coronary artery calcification and all-cause mortality.
OBJECTIVE
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.
Blaha
Michael
M
Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Baltimore, MD 21287, USA.
Budoff
Matthew J
MJ
Shaw
Leslee J
LJ
Khosa
Faisal
F
Rumberger
John A
JA
Berman
Daniel
D
Callister
Tracy
T
Raggi
Paolo
P
Blumenthal
Roger S
RS
Nasir
Khurram
K
D000368:Aged; D000530:Alfaxalone Alfadolone Mixture; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000401:mortality*; D002423:Cause of Death; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000401:mortality*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011859:Radiography; D012307:Risk Factors; D016019:Survival Analysis
D000530:Alfaxalone Alfadolone Mixture