Coronary Artery Calcium Scoring

Author: Dr Charles Lott*

What are the prerequisites for having coronary artery calcium scoring done?

Coronary artery calcium scores are of most use in those patients at intermediate risk for cardiovascular disease, where the result will either lower or raise the risk profile and provide a change in management.

Those at low risk (such as an asymptomatic 35 year old male non-smoker who exercises and has no significant family history) and those at high risk (such as a 60 year old obese male long-term smoker with chest pain on exertion) would not benefit from the study.

In general, coronary artery calcium score CT scans are most useful in women between 35 and 70 years and in men between 40 and 60 years.

There is a place for scans outside these ranges. For example, finding a score of zero in an elderly man will indicate a very low risk of a cardiac event; however, this result is very unusual in the general population.

The test is valid for main ethnic groups; however, the result is most accurate in patients of Caucasian origin. coronary artery calcium scoring in patients on dialysis and with established long-term diabetes is not recommended, due to the high likelihood of a high score and the current scientific uncertainty over the interpretation of the result.

It must be stressed that there is potential for a technically false result. A score of zero does not exclude the possibility of myocardial infarction in the future.

What are the absolute contraindications for coronary artery calcium scoring?

Any contraindication to X-ray exposure, of which pregnancy is the most common.

What are the relative contraindications for coronary artery calcium scoring?

The very young and very old will get no benefit from a calcium score.

Any patient with high risk of coronary event and symptoms should have appropriate investigation and treatment urgently.

Anyone who has already had a myocardial infarction or coronary re-vascularisation will not have any benefit with the information from a calcium score study.

All scanners have physical limitations due to table weight limits and the diameter of the scanner aperture. Older scanners are able to scan patients up to 150kg. Newer scanners can in some cases accommodate patient weights of 220 – 250kg. Some obese patients have large abdominal girths. Most scanners have a gantry diameter of about 68cm with newer scanners up to 78cm. If you are concerned that your patient may exceed any of these limits, it is best to contact the hospital or practice to find out whether this may preclude scanning.

What are the adverse effects of coronary artery calcium scoring?

Radiation risks are discussed in detail in another information item on InsideRadiology (see radiation risk of medical imaging in adults and children).

Are there alternative imaging tests, interventions or surgical procedures to coronary artery calcium scoring?

Alternative strategies exist to assess the personal risk of a cardiovascular event. Risk stratification techniques to assess a ten–year individual risk of a cardiovascular event include:

  • Framingham risk score (FRS)
  • PROCAM score
  • European SCORE system

These are in wide usage but tend to have a heavy weighting to patient’s age and may not adequately take into account lifestyle factors such as smoking, diet, exercise, and body mass index.

Alternative methods of imaging or testing to better stratify the individual’s risk include:

  • Intima-media thickness (IMT) – ultrasound measurement of carotid artery wall intimal layer thickness. This is requires very high level of experience to perform well and is difficult to reproduce routinely.
  • Inflammation markers such as CRP/ESR – general non-specific screening tests that have association with atherosclerosis and risk.
  • Biochemical screening – including lipid and lipoprotein profile, diabetes, plasma homocystine levels, lipoprotein A levels. These are very general in their use but either of low prevalence or poor at discrimination between risk levels.
  • Exercise stress test – this assesses functional ability of the cardiovascular system compared with an age and sex matched cohort. This common test provides information above that of the Framingham risk, but has a high false negative rate.
  • Stress echocardiography – a functional imaging of myocardium with and without cardiac stress. An excellent test of myocardial function. It does not provide a good indication of atherosclerosis and is better used in assessment of symptomatic patients.
  • Stress nuclear myocardial scintigraphy – a functional imaging test of myocardium with and without cardiac stress. Requires significant radiation dose. An excellent test of myocardial function. It does not provide a good indication of atherosclerosis and is better used in assessment of symptomatic patients.

Further information about coronary artery calcium scoring:

References: These major review articles may be helpful in adding detail and depth to the information given:

  • Greenland P, Bonow RO, Brundage BH et al, ACCF/ AHA 2007 clinical expert consensus document on coronary artery calcium scoring by computed tomography in global cardiovascular risk assessment and in evaluation of patients with chest pain: a report of the American College of Cardiology Foundation Clinical Expert Consensus Task Force, (ACCF/AHA Writing Committee to Update the 2000 Expert Consensus Document on Electron Beam Computed Tomography). Circulation (2007) 115:402–426
  • Oudkerk M, Stillman AE, Halliburton SS et al, Coronary artery calcium screening: current status and recommendations from the European Society of Cardiac Radiology and North American Society for Cardiovascular Imaging, Int J Cardiovasc Imaging (2008) 24:645–671 DOI 10.1007/s10554-008-9319-z

Useful websites about coronary artery calcium scoring:

*The author has no conflict of interest with this topic.

Page last modified on 26/7/2017.

Related articles