Heart disease is the leading cause of death in the United States — and this holds true across gender and most racial and ethnic groups. Coronary artery disease (CAD) is the most common type of heart disease and impacts blood supply to the heart muscle. Although an estimated 1 in 20 people age 20 and over are already living with the condition, many people don’t realize they have CAD until they experience a heart attack or stroke.
Though these odds may sound worrisome, there are ways to assess your risk of heart attack and stroke, and in some cases, even catch CAD before symptoms develop.
A coronary calcium scan — also referred to as a coronary artery calcium (CAC) scan or a heart CT calcium scan — is a simple, noninvasive test that not only screens for CAD but also helps determine your heart attack risk.
Below, Thomas C. Gerber, M.D., cardiologist with Mayo Clinic in Rochester, Minnesota and a professor of medicine and radiology at Mayo Clinic College of Medicine and Science, breaks down exactly how a coronary artery calcium scan works and what to expect from the assessment.
What is a coronary artery calcium scan?
A coronary calcium scan is a computerized tomography (CT) scan of the heart, says Dr. Gerber. “Because the heart moves constantly, these scans are done with specialized CT scanners that can ‘freeze’ the heart’s motion, allowing for a more accurate assessment of the heart’s condition.”
Though this sounds technical, the scan itself is short and painless. According to Dr. Gerber, there is no preparation on your part. There are no needles, and the scan does not cause any physical discomfort. “You will be asked to hold your breath and lie still, but the scan itself takes just a few seconds — the procedure will be over before you know it,” he says.
As the name implies, the purpose of the coronary calcium scan is to detect any calcium deposits in the arteries — also called the “coronary arteries” — that supply blood to the heart muscle.Cholesterol and other substances form artery-narrowing plaque in the arteries, and this builds up slowly over time. If the plaque grows big enough to reduce blood flow to the heart muscle, the resulting blockage can sometimes trigger a heart attack.
Assessing this calcium buildup is important because the more calcium that is present, the more plaque is likely to be present as well. And the more plaque you have, the higher your risk of coronary artery disease and heart attack, even if the plaque is not yet big enough to reduce blood flow to the heart muscle.
How coronary calcium scans determine heart attack risk
After the scan, specially trained technicians process the CT images and calculate your coronary artery calcium score. This number, sometimes called the Agatston score, estimates your heart attack risk.
“The CAC score is a measure of how much plaque there is in the coronary arteries,” says Dr. Gerber. “Put simply, the higher the CAC score, the more plaque is likely present. And the more plaque there is, the higher the risk of a serious heart attack over time.”
If you receive a score of zero, there was no calcium present in the scan and your risk of a heart attack is considered low for the near future. A score ranging from 100 to 300 indicates a moderate amount of calcium and suggests a relatively high risk of heart attack or other heart disease over 3 to 5 years. Finally, a score above 300 may indicate more extensive heart disease and a higher risk of heart attack.
“Remember that a coronary calcium scan, if needed, is just one of many factors that your healthcare team considers when helping you manage your cardiovascular risk,” says Dr. Gerber. In other words, having some calcium present does not automatically mean that a heart attack is inevitable.
“Coronary calcification becomes more common as people get older. For example, at age 70, approximately 70% of men have calcium present,” says Dr. Gerber. “Also, if you are a very active athlete, your CAC score may be higher than expected, but in this situation is not thought to indicate higher cardiovascular risk.”
Simply put, a coronary calcium scan is a risk assessment tool to help you and your healthcare team learn more about your heart health and determine what medication or lifestyle changes, if any, would benefit you. “Trust that your healthcare team will carefully explain to you what your CAC score means in your individual situation, and what should be done with the information,” says Dr. Gerber.
Who should get a coronary calcium scan?
Although a coronary calcium scan is an effective tool to diagnose CAD and assess the risk of heart attack, it’s not right for everyone.
According to Dr. Gerber, a coronary calcium scan is typically most helpful for people with an intermediate risk of heart attack or other cardiovascular issues. Your specific risk of heart attack or stroke is determined by a number of factors such as your age, sex and race, as well as clinical markers such as blood pressure, cholesterol levels, ongoing tobacco use and diabetes diagnosis.
If your cardiovascular risk is considered either low or high, Dr. Gerber says the scan is rarely useful. Likewise, the scan is not recommended for people who have already had a heart attack or stroke, or those who have received coronary stents or heart bypass surgery. In any of these cases, your healthcare team will already know you have heart disease. “Remember that a coronary calcium scan is a screening test that is meant to discover previously unrecognized coronary disease,” says Dr. Gerber.
However, even if your cardiovascular risk is low, there are some special cases where a scan may be helpful. “For example, if you are a younger person with first-degree relatives, such as a parent or sibling, who had heart attacks or strokes younger than age 55 for men or age 65 for women, a coronary calcium scan is reasonable,” says Dr. Gerber.
Remember, heart disease is a treatable — and, in many cases, preventable — condition. Assessment tools like coronary calcium scans can help you and your healthcare team better understand your risk and assess how to best protect your heart health and lower the risk of heart attack.
If you’re concerned about your cardiovascular health or heart attack risk, speak with your healthcare team about the best risk assessment options for you.
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