Q) My doctor has suggested I take test called a calcium scan. Why would she suggest this and what do I need to know about it?
A) When most people think about calcium, we tend to think in terms of bone health, but in fact, the amount of calcium in our arteries (the blood vessels which deliver blood from our heart to our organs) is a very important indicator of our heart health as well.
Plaque, the sticky substance that builds up over the years and can clog up our arteries is made up partially of fat and calcium. Plaque starts off being almost wax-like in its consistency, but over time it hardens as it becomes calcified. This is important because this hardened plaque slows down the flow of blood meaning that some parts of your body (including the heart ironically enough) do not get enough oxygen (remember from science class that our blood is the medium by which oxygen is carried to the rest of our body) to function properly. This is also critical because this hardened plaque can spontaneously break-off and travel to your heart or brain causing a heart attack or a stroke respectively.
So, in essence, a calcium scan is checking for signs of heart disease, which is still the number one killer of Canadians, as it has been for years. Calcium scan tests are also known by a number of other names including a coronary calcium scan and a cardiac CT for calcium scoring.
It is a completely non-invasive test that uses a special computed tomography scanner that takes multiple pictures of your heart similar to what an x-ray does. The scans are then combined to produce a view that reveals the specks of calcium within the walls of the arteries. This mount of calcium is then scored on a scale ranging from 0 to over 300. A score of zero indicates that there is no evidence of calcified coronary plaque while a score of over 300 indicates that the amount is severe (for interests sake the rest of the scale reads as; 101-300 is regarded as a moderate amount, 11-100 mild and 1 to 10 minimal) and that action must be taken.
While this test is very useful and being conducted far more often than it used to be, this test should not be run on everybody. This is because it exposes the recipient to radiation, about the equivalent of what they would normally be exposed to over a full year of regular living. While this is regarded as still a safe amount, there is never any sense in increasing our exposure without a good reason.
As well, this test costs money to taxpayers (thereby leaving less money for our health care costs like hospitals and mental health programs) and makes those who really need it have to wait in the “queue” longer so the key is to decide who really needs to have this test done.
For those people, of whom we are almost certain they are at a low risk of heart disease, this test does not make any sense as its likely to come back with a low score and have all the negatives described above attached to it. This group would include most people under the age of 40.
As well, for those with well established heart disease, this test is also probably not useful as it’s simply going to tell us what we already know to be true. However, this test can be very illuminating when we are uncertain about a person’s risk for heart disease or if we are uncertain about adding another prescription drug (more than likely a “statin” to reduce cholesterol) to a patient’s current regimen.
This medium risk group includes those between the ages of 40 & 75 whose 10 year risk of heart disease or stroke ranges from 7.5% to 20% (as calculated by a risk assessment formula such as the Framingham Coronary Heart Disease risk calculator).
For these people, this scan can help define or even reclassify a person’s risk of cardiovascular (CV) disease allowing the physician to more accurately treat (or conversely not to treat) before real health problems occur.
For example, say your risk of having a CV event as calculated by Framingham is 10% but your scan comes back with a zero. This would in theory cut your actual risk in half and may allow you to avoid taking a statin since they aren’t generally recommended for people who have less than a 7.5% chance of having a stroke or heart disease in the next 10 years.
The test itself takes about 30 minutes to perform and involves a lab technician applying a few sticky patches to your chest (after a tobacco and caffeine free morning of course) which are connected to an EKG machine which helps the person running the scanner know when to take the pictures. You’ll be lying on your back on a table that slides into a hollow tube, which is the scanner itself. You’ll be in there for 10 to 15 minutes so those with claustrophobia issues may need medication to help them relax.
There is no pain involved and once it’s over, you should be fine to resume your day. All in all, it’s a small inconvenience that might provide a lot of vital information about your cardiovascular system.