A coronary calcium scan checks for presence of calcium in the walls of the coronary arteries, termed as calcification as these are an early sign of plaque development in the heart’s blood vessels. Calcium scans thus tell if you are at increased risk for a heart attack.

A coronary calcium scan is essential for people at moderate risk for a heart attack. CAD risk factors include high blood pressure, smoking, high cholesterol, diabetes and a family history of prevalence of the problem.
No special preparation at home is required as such for a coronary calcium scan. To perform the scan, an X-ray machine known as a computed tomography (CT) scanner is used. A technician will clean parts of your chest and apply small sticky patches called electrodes. The electrodes are fixed to an EKG (electrocardiogram) monitor which measures the electrical activity of your heart during the scan. Images of your heart are taken when it is relaxed, between beats.

The calcium scan takes about 5 to 10 minutes. During the scan, the machine makes clicking sounds while taking pictures. It causes no discomfort, only the exam room needs to be chilly to keep the machine working. If you get nervous in enclosed spaces, you will be administered medicine to stay calm. Your head will remain outside the opening of the machine.

Calcium Scans
United Kingdom

Having a calcium scan is similar to having any x-ray. You will be made to lie on an x-ray table, wires will be attached to your chest to record an ECG. The computerized x-ray image received will be examined for the telltale "white spots" that signify calcium deposits in the coronary arteries, and the amount of calcium will be quantified into a calcium score.

The usefulness of calcium scans greatly depends on your level of risk for CAD.

People in the low risk category have such a low probability of having a positive scan that it is generally suggested that they not have calcium scanning. People in the high risk category have such a high chance of having a positive calcium scan that in fact very little is gained by actually taking the scan. So, it is people in the intermediate risk category who actually benefit from calcium scans. These individuals usually seem to be healthy, except for a few risk factors that may be only a little abnormal. A calcium scan in such cases are very helpful. If the calcium score is moderate or high, that means active CAD is already present and these people are at high (and not intermediate) risk for heart attacks. Hence, immediate steps should be taken for risk factor modification. On the other hand, if the calcium score is low, then little or no CAD should be present and less aggressive risk factor modification (such as improving lifestyle choices) will be required. 

Calcium Score Screening Test
Wellington Hospital, London

A calcium score refers to a screening test used to find out the amount of calcium in the heart. A calcium score studies the calcium in the coronary arteries, the areas where increased calcium has lead to narrowing of the artery.  The narrowing in the artery usually results in a heart attack.

A calcium score is taken to see if a patient is at high risk for coronary artery disease, which may lead to a heart attack.  A high calcium score means a higher risk of cardiovascular events, while a calcium score of zero means there is a very low risk of coronary artery disease or heart attack.

A calcium score is seen as a "screening" test.  The main screening test used by physicians to find out if coronary artery disease is present is known as the Framingham Risk Score. This risk score is used by physicians to analyze which patients should be treated with cholesterol medications. 

However, the Framingham Risk Score is not very reliable, as people may have a heart attack even with low risk score.  At present, calcium scores are not recommended as a screening tool by the most of medical associations, but they provide additional information that may come in use in certain situations. 

With new 64-slice CT scanners there everywhere these days, be sure to get your heart scan with it.

The new scanners do provide really good images of the coronary arteries. But, say you have a 20% blockage in an artery by a coronary angiogram generated on one of these devices. What will you do in 1, 2, or 3 years when you want to find out if you have progressed? Should you have the CT angiogram done again?

If you did you'll be exposed to a huge dose of radiation--appropriate for a diagnostic test, but not for a screening test. The radiation exposure is similar to undergoing a full conventional cardiac catheterization, or up to 100 chest x-rays.

"20% blockage" is also just an estimate of the diameter reduction at one spot. That number reveals nothing about the lengthwise extent of plaque or about the potential for "remodeling", that is the phenomenon of artery enlargement that takes place as plaque grows. So if you had another CT coronary angiogram a year later and was told that your blockage was still 20%, actually you could have had considerable plaque growth but it would not be shown in that value.

People will come to me after getting a CT angiogram for a suggestion. I have to send them back to their scan center to get a simple coronary calcium score. That measure is easy, quantitative, precise, and can be repeated annually to note the progression. Some physicians ridicule the heart scan, or calcium, score--it's old, boring, only a measure of hard plaque. But that is not true at all. The coronary calcium score is a measure of total plaque (hard and soft). And when you know how to control and reduce your score, then it's the most exciting number in your entire health program!

So if you go to a scan center and they direct you to a 64-slice CT scanner, or if your doctor orders one, you should insist on getting a calcium score out of the test. Centers that refuse to generate a score certainly have one thing on their mind: identifying people with severe blockages sufficient to obtain the downstream financial bonanza--angioplasty, stents, and bypass surgery.