CT Coronary Calcium Score

Coronary Artery Calcium Scoring (CAC) is a non-invasive assessment of coronary artery calcification using computed tomography (CT). It is a marker of atherosclerotic plaque burden (hardening and narrowing of the coronary arteries). It is also an independent predictor of future cardiovascular events such as heart attacks.

Its use for risk stratification is confined to patients who never had a cardiovascular event before in the past (primary prevention).

ct calcium score

Patient groups to consider Coronary Calcium Scoring

  1. CAC is of most value in intermediate risk patients aged 45-75 years, who are asymptomatic and who do not have known coronary artery disease. In such patients it may have the ability to reclassify patients into lower or higher risk groups.
  2. It may also be considered for lower risk patients, e.g. for those with a family history of premature CVD and possibly in patients with diabetes aged 40 to 60 years of age.

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Patient groups in whom Coronary Calcium Scoring should not be considered

CAC is not recommended for patients who are:

  1. Very low risk
  2. High risk – as testing is unlikely to alter the recommended management
  3. Symptomatic or previously documented coronary artery disease.

Interpretation of CAC

CAC = 0. A zero score confers a very low risk of death, <1% at 10 years.

CAC = 1-100. Low risk, <10%

CAC = 101-400. Intermediate risk, 10-20%

CAC = 101-400 & >75th centile. Moderately high risk, 15-20%

CAC > 400. High risk, >20%

Management recommendations based on CAC

Optimal diet and lifestyle measures are encouraged in all risk groups and form the basis of primary prevention strategies. Patients with moderately-high or high risk based on CAC score are recommended to receive preventative medical therapy such as aspirin and statins. Generally aspirin and statins are recommended if the CAC is >100.

Repeat CAC testing

In patients with a CAC of 0, a repeat CAC may be considered in 5 years but not sooner.

In patients with positive calcium score, routine re-scanning is not currently recommended. However, an annual increase in CAC of >15% or annual increase of CAC >100 units are predictive of future heart attacks and death.