Coronary Artery Calcification Scoring

What is Coronary Artery Calcification Scoring (CACS)?

A Coronary Artery Calcification Score is calculated following a cardiac CT scan.  A cardiac CT scan is a non-invasive radiological means of obtaining information about the location and extent of calcified plaque in the coronary arteries. Plaque is a build up of fat and other substances, including calcium, which can, over time, narrow the arteries and restrict blood flow to the heart. Restricted blood flow to the heart can impair its performance. If a plaque “ruptures” it can lead to a blood clot occluding the artery and causing a heart attack. With the high speed CT scanner the radiation dose is relatively low and equivalent to approximately 8 months background radiation. The adverse effect of this dose of radiation is considered to be very small but not insignificant.

Calcium Scoring Overview

Arterial Calcium is a marker for plaque or atherosclerosis (hardening of the arteries). The amount of calcium detected in a coronary artery by the CT scan correlates with the presence and amount of atherosclerotic plaque. These calcium deposits may appear years before the development of heart disease symptoms such as chest pain and shortness of breath. It is a much more sensitive indicator of silent coronary artery disease than a stress test.

A calcium score is computed for each of the coronary arteries based upon the volume and density of the calcium deposits. It is only semi quantitative but does correlate with the severity of the underlying coronary atherosclerosis.

The degree of atherosclerosis and calcium detected on the CT scan increases with age. The result or CAC score is reported as a percentile comparing the individual to asymptomatic people of the same age and gender. The calcium score, in combination with the percentile, enables physicians to determine the risk of developing symptomatic coronary artery disease, and help determine whether treatment is indicated.

Calcium scores and what they mean

A score greater than zero indicates at least some coronary artery disease. As the score increases, so does the likelihood of significant coronary artery narrowing and the likelihood of a coronary event, such as a heart attack, over the next 5-10 years, compared to people with lower scores. However, a score of zero does not necessarily indicate no disease as plaque may be non-calcified.

The age of the patient is taken into consideration when determining the significance of the score. A low score in a younger patient may be very significant and indicate premature disease.

Calcium scores provide patients and their doctors with additional non-invasive information on a patient's risk of heart disease which can help to determine if any further tests should be performed and whether medication as well as lifestyle changes would be beneficial. Treatment can slow progression and even reverse the formation of plaque.

Who should have this test?

This screening test is most useful in men over the age of 50 and women over the age of 55 with an uncertain risk of cardiovascular disease. It may be recommended in younger men (> 46 yrs) and women (> 50 yrs) if they have one or more of the following risk factors:

· Abnormal blood cholesterol profile

· Family history of coronary artery disease (heart

      attack, angina) at a young age (< 60 yrs)

· High blood pressure

· Smoking

· Diabetes

· Obesity

How should I prepare for the procedure?

No special preparation is necessary in advance of a CACS scan. You may continue to take your usual medications, but should avoid caffeine and smoking for four hours prior to the exam as better images are obtained with a slower heart rate. You will be connected to an ECG so that images can be obtained between heart beats. The whole procedure may take 30 minutes but you are only in the scanner for a few minutes. An appointment is necessary and it is recommended that the test is done at a centre with experience in CACS and a 64 slice CT scanner. The cost of the test is not covered by Medicare or Health Benefit Funds.

How does the procedure work?

CT imaging uses special x-ray equipment to produce multiple images or pictures of the inside of the body and a computer to join them together in cross–sectional views of the area being studied. CT imaging is sometimes  compared to looking into a loaf of bread by cutting the loaf into thick slices. When the image slices are reassembled by computer software, the result is a very detailed multidimensional view of the heart and blood vessels.



This diagram illustrates the main coronary arteries of the heart

 

Please note:

Even patients with a low calcium score may develop serious blockage of the coronary arteries and/or  experience a heart attack. If you experience chest pain, heaviness or discomfort or shortness of breath, you should seek medical care immediately.

For more information

Wesley Corporate Health

Level 2, 46 Edward St

Brisbane  Qld  4000

Phone: 07 3234 2600

Email: info@weshealth.com.au

Heartline (National) 1300 362 787

Disclaimer

This Fact Sheet is provided for your information only and does not replace qualified medical advice. The information provided may not apply to every person or all situations. A medical practitioner should be consulted for all treatment and medication.