What Is a Coronary Calcium Scan?
You’ve probably heard how good calcium is for your bones. But did you know calcium might be a big clue to your heart health, too?
Your doctor can use what’s called a coronary calcium scan to get a clearer picture of your risk of having a heart attack.
This heart scan uses a special type of X-ray called a CT scan. It takes pictures of your arteries, the vessels that carry blood away from your heart, to check for calcium.
You may hear this scan called by several names:
- Coronary calcium scan
- Calcium scan test
- Cardiac CT for calcium scoring
The Importance of Calcium in Heart Health
In some ways, calcium is good for your heart health. It plays important roles in the organ's electrical and pumping activities, allowing it to keep a steady rhythm and keep your blood moving. Calcium also helps your blood clot normally and helps to manage blood pressure.
But calcium also plays a role in atherosclerosis, a condition in which fat and cholesterol deposits called plaque build up inside your arteries. When you have plaque in your heart arteries, that's coronary artery disease. It increases your risk of a heart attack.
Here's where calcium comes in: As you age, calcium from your bloodstream can settle in parts of your body. Arteries already damaged by plaque buildup and inflammation tend to attract these calcium deposits over time. When that happens, you have what doctors call coronary artery calcification. It makes arteries stiffer and narrower.
Most people over age 70 and almost everyone with coronary artery disease will have at least some of these calcium deposits.
One thing that's not clear: whether there's a connection between the amount of calcium in your body overall and your risk of heart disease. Some studies have linked calcium from supplements, but not calcium from foods, with an increased risk. Others have found no link.
Why Should You Have a Calcium Score Test?
The scan is done to see if you have any calcium deposits in your arteries and, if so, how many. High amounts of calcium mean you have high amounts of plaque.
That's worrisome, for two reasons.
First, hard plaque in your arteries is like a clog in a pipe. It slows your blood flow. That means some parts of your body don’t get enough of the oxygen they need. If plaque collects in your heart’s arteries, you may feel chest pain and discomfort, called angina.
Second, that plaque can break open, which can lead to a blood clot. That could cause a heart attack.
Once you know how much calcified plaque is in your heart’s arteries, you and your doctor can decide if you need to make any changes to your medicine or lifestyle.
When Should You Have a Calcium Score Test?
The coronary calcium scan isn’t for everyone.
Your body is exposed to radiation during the test. Because of that, you want to get this scan only if it can tell you something useful.
First, you need to know how likely you are to get heart disease. Your doctor has ways to figure this out based on:
- Your age
- Your blood pressure
- Your cholesterol level
- Whether you smoke
- Your gender
Heart scans make the most sense if you have a moderate, or medium, chance of heart disease based on these things. Typically, that means you are between ages 40 and 70, with some heart risks but no symptoms.
If you have only a low chance of coronary artery disease, the test isn’t likely to show any calcium. If you have a high chance, you won’t learn anything more that can help you. In both of these cases, you’d be exposed to extra radiation for no good reason.
But if you have a medium chance, you may be able to take steps to avoid heart disease based on the scan results.
For example, the test might help people who are struggling to decide whether to take a statin to lower their cholesterol or resume statins after having some side effects.
Insurance usually doesn’t cover this kind of scan. So it’s a good idea to check on that before you get the test. The cost is usually around $100 to $400.
How Does the Coronary Calcium Scan Work?
The test uses a CT (computed tomography) machine, which is a special kind of X-ray equipment that uses a small amount of radiation. The machine will scan your heart to take detailed images. Any calcium specks on the walls of your heart arteries will show up on the images. You don't have to take any sort of dye for this test.
A technician will do the test, and then your doctor will look at the results. You'll get a score based on how much calcium is found.
The machines used can vary. Your hospital or clinic may use a high-speed CT machine called a multidetector CT (MDCT). Or it may use another kind of fast CT called electron beam computed tomography (EBCT). Both quickly take multiple images that a computer can combine into detailed 3D pictures. They have similar accuracy.
What Can You Expect During the Calcium CT Scan?
You will visit a hospital or clinic that has a CT scanner. Your doctor may ask you to avoid caffeine or smoking for up to 4 hours before the test.
For the scan, you’ll wear a hospital gown, so you’ll need to take off your clothing and jewelry from the waist up.
The person who runs the scanner will put a few sticky patches on your chest. These patches connect to what’s called an EKG (electrocardiogram) machine, which helps the person running the scan know exactly when to take pictures of your heart.
If you get nervous in closed or tight spaces, you can get medicine that will help keep you calm. You may also get medicine to slow your heart so they can take better pictures.
During the test, you’ll lie on your back on a table that slowly moves into the CT scanner. The scanner is a hollow tube, so it’s like sliding into a short tunnel. Your head and feet will stick out of either side of the tube once you are in place.
The person running the scan stands on the other side of a glass wall and uses a speaker to talk to you. The scan itself takes just a few seconds. But your total time in the exam room might be 10 to 15 minutes. Once you’re done, you can go about your day.
Understanding Your Cardiac Calcium Score Results
The scan gives you a number called an Agatston score. Your doctor may get your results the same day of the test, but it can take longer.
A score of zero means the test didn’t find any calcium. If the test does find calcium in your arteries, higher numbers mean a higher risk of heart problems and a greater need for you and your doctor to come up with a plan. Here's how you might see the results interpreted:
| CALCIUM SCORE | PRESENCE of CAD (coronary artery disease) |
|---|---|
| O | No sign of CAD |
| 1-10 | Minimal signs of CAD |
| 11-100 | Mild signs of CAD |
| 101-400 | Moderate signs of CAD |
| 401 and higher | Extensive signs of CAD |
You might also get a percentage score, showing how the amount of calcium in your arteries compares to amounts found in other people of the same age and sex. Scores of 75% or higher – meaning you have more calcium in your arteries than 75% of people like you – are linked with a higher risk of heart attacks.
Keep in mind that high scores don't mean you’re sure to have a heart attack. But they do signal that you may need to make some changes to lower your risk.
If you have no sign of coronary artery calcification, that means you have a very low risk of having a heart attack in the next 2 to 5 years.
Coronary Calcium Score Screening Follow-Up
Your doctor can help you understand what your score means for you. Based on the results, you may need more tests. You might also make changes in:
- How much exercise you get
- What you eat
- Weight goals
- What medicines you take
Tests results often help people decide whether or not to take statins, prescription medicines that lower levels of harmful cholesterol, reducing your risk of a heart attack and stroke. The medicines don't cost much and are well-tolerated by most people, but they can come with side effects such as muscle pain, digestive problems, mental fuzziness, and, in rare cases, liver damage.
If you are otherwise at low risk and a coronary calcium scan shows no plaque buildup, you might decide not to take medicine and get tested again later. If your scan shows a lot of plaque, that might move you toward taking the statins.
Once you've had a scan showing calcified deposits, in any amount, there's no need to take another scan. You already know you have plaque buildup.
Reducing the Risk of Coronary Artery Calcification
You can reduce your risk of coronary artery calcification by preventing and treating conditions that contribute to it, including:
- Diabetes
- Abnormal cholesterol levels
- High blood pressure
- Kidney disease
More generally, you can prevent or slow the progression of coronary artery disease and calcification by:
- Limiting cholesterol, fat, and salt in your diet
- Not smoking or quitting smoking
- Avoiding alcohol
- Managing your weight
Takeaways
Not everyone needs a coronary calcium scan, but for some people, it can provide valuable information about heart disease risks. The test involves a simple CT scan. The results will help you and your doctor decide how best to limit your heart disease risks.
Coronary Calcium Scan FAQs
Are coronary calcium scans worth it?
It depends. If you already know you have coronary artery disease, a scan won't tell you anything useful. Likewise, if you're a young adult with no known heart risks, it's unlikely to find a problem you can act on. It's generally only recommended for people at moderate risk who might get some useful information.
Does a coronary calcium scan show blockage?
Not directly. It gives your doctors a good idea of how much plaque buildup is in your arteries, but it doesn't show how well blood is flowing through them. Other tests can do that.
What is a good calcium score by age?
The best coronary calcium score at any age is zero, meaning you have no sign of calcification in your arteries. That said, your doctor may give you a percentage showing how your calcium buildup compares with other people's who are your age and sex. When there is calcium present, it's often seen earlier and in higher amounts in men. For example, one study in Turkey found that a woman in her late 60s with a score of 104 had more calcium buildup than 75% of women her age; for men in their late 60s, a score of 313 put them in that category.
Why doesn't insurance cover coronary calcium scans?
Some insurers, in some states, will cover them. But Medicare and most other insurers don't. These insurers have said that the reason is a lack of strong scientific studies showing that the testing changes outcomes – things like how many heart attacks or how many heart deaths are prevented. Heart health advocacy groups argue that the evidence for the scan is at least as strong as evidence for some other tests that are routinely covered.
