coronary artery calcium (CAC testing)

Indications

• assessment of asymptomatic coronary artery disease
  • reasonable test in patients with intermediate risk of coronary artery disease*
    • not recommended for patients at low or high risk
  • may identify subset of patients who would likely derive benefit from aspirin &/or statin therapy
  • might help stratify cardiovascular risk in patients with diabetes mellitus type 2

* Framingham risk score 10-20%

* adults 40-75 years without diabetes, with LDL 170-190 mg/dL, & 10-year cardiovascular risk of 7.5-20%

Contraindications

• coronary computed tomography angiography of no benefit in calibrating intensity of preventive therapy in patients with diabetes mellitus

Advantages

• scores are predictive of cardiovascular risk
• better than polygenic risk score

Disadvantages

• radiation exposure
• does not provide data on coronary artery luminal narrowing

Clinical significance

• absence of coronary artery calcification (score = 0) associated with low risk for cardiovascular events
  • no statin needed if intermediate 10-year cardiovascular risk ACC/AHA 7.5%-20%, USPSTF 10%-20% & asymptomatic
• positive correlation between coronary artery calcium volume & cardiovascular risk
• negative correlation between coronary artery calcium density & cardiovascular risk
• coronary artery calcium scores predict all cause mortality
• coronary artery calcium noted incidentally on chest CT increases with age
  • men have higher prevalence of detectable oronary artery calcium than women
    • non hispanic white men with highest prevalence, > 50% by age 50-54 years
• coronary artery calcium at age 40 associated with increased risk for coronary artery events in the next 10 years
• coronary artery calcium scores of zero less predictive of cardiovascular risk in patients < 40 year than in older patients
• coronary artery calcium scores can improve cardiac risk assessment in intermediate-risk patients
• very high coronary artery calcium scores (> 1000) associated with increased risk for cardiovascular events (RR=4.7) & all-cause mortality (RR=1.9)
• coronary artery calcification present in 36% of women with calculated 10 year cardiovascular risk of < 7.5%
  • harm vs benefit of testing low risk women of concern
• coronary artery calcification assessed by computed tomography may have predictive value for myocardial infarction in patients with at least 1 traditional risk factor (see coronary artery disease).
• the absence of coronary artery calcification does not exclude obstructive coronary artery disease in symptomatic people who are referred for angiography
• overall sensitivity of a coronary artery calcification score of 0 for predicting absence of coronary artery disease is 45%
• may be useful for identifying patients with chest pain who can be discharged home without further testing
  • lack of coronary artery calcification identifies low-risk patients
• may be useful for reclassifying patients with intermediate-risk of acute coronary syndrome, myocardial infarction &/or sudden cardiac death
• predicts stroke risk in people at low to intermediate risk
• incidental finding of coronary artery calcification on CT of thorax allegedly has clinical significance
  • authors suggest a statin plus an aspirin
• predicts 10-15 year mortality
• coronary artery calcification associated with higher levels of lifelong physical exercise in men
  • suggested to be a benign condition
• high levels of physical activity (>= 3000 MET-min/week) associated with prevalent coronary artery calcium, but not associated with increased mortality even with high coronary artery calcium
• positive, graded association between physical activity & prevalence & progression of coronary artery calcium, regardless of baseline scores
• calcification may stabilize coronary artery atherosclerotic lesions

Procedure

A computed tomography procedure - electron beam CT or spiral CT

• coronary artery calcium is measured by its radio-opacity
• scores of < 1 consistent with no calcification
• scores of 1-10 constent with low calcification
• scores of > 10 consistent with high caclification

Management

• if coronary artery calcium score is >= 100, a statin should be initiated

Notes

• used to assess air pollution as cardiovascular risk factor
• arterial calcification noted on digital mammography predicts coronary artery calcium*

* article withdrawn at request of author(s) &/or editor

More general terms

• CT of heart

Additional terms

• cardiac computed tomography angiography; coronary computed tomography angiography; CT angiography (CCTA)
• coronary artery calcification