Heart scans use noninvasive techniques to measure the amount of calcium in the walls of your coronary arteries — the arteries that supply your heart with blood. Having calcium in the walls of your arteries indicates that you may develop coronary artery disease.
Coronary artery disease is a leading cause of heart attacks and death. Coronary artery disease occurs when plaques build up within the walls of your heart arteries, causing narrowing (atherosclerosis). The plaques are deposits in the artery walls made of fat, cholesterol and calcium. Heart scans can detect the calcium in those plaques. The amount of calcium in plaques can be used to calculate a score that, when combined with other health information, helps determine your risk of coronary artery disease or heart attack.
Use of heart scans has been controversial. Heart scans may not be useful for you if, based on your family history and risk factors, you fall into either a low- or high-risk category for having a heart attack. The American College of Cardiology and the American Heart Association have created guidelines to determine if a heart scan may be useful in deciding whether you need to take action to prevent a heart attack within three to five years.
A heart scan isn't useful if you have:
- Low heart attack risk. If, for example, you are younger than 55 years old, have normal cholesterol and blood pressure levels, and don't smoke, your heart attack risk percentage may be calculated at less than 10 percent, putting you in the low-risk category. It means that because you have few risk factors, you have less than a 10 percent chance of having a heart attack in the next 10 years. So if you're at low risk, a heart scan probably won't tell you anything you and your doctor don't already know.
High heart attack risk. Having a 20 percent or greater risk of having a heart attack in the next 10 years means you're at high risk. If you have high cholesterol levels and high blood pressure, smoke, and are older than 65, you'd likely be in this category. If you're at high risk, a heart scan won't do you much good. That's because you and your doctor already know that you're at risk based on your risk factors and that you should take steps to prevent a heart attack, such as taking medications or making significant lifestyle changes.
You also shouldn't have a heart scan if you've already had a heart attack or have had a surgical procedure, such as angioplasty or coronary bypass surgery, to treat coronary artery disease. In these cases, your doctor will already know you have coronary artery disease and you're at a high risk of having a heart attack. A heart scan won't provide any more information on how your condition should be treated.
When a heart scan might be useful
A heart scan may give you information about your heart attack risk if you fall into the intermediate heart attack risk category. This means, based on your risk factors, your risk of having a heart attack in the next 10 years falls somewhere between 10 and 20 percent. For example, you may be considered to have an intermediate heart attack risk if you're between the ages of 55 and 65 years and you have borderline high cholesterol or blood pressure or are a smoker. Your doctor can help you determine what your risk level is. A heart scan may be useful if you're at intermediate risk or if you have chest pain, especially if it's unclear whether a heart problem is the culprit.
Also, there is some evidence that people whose calcium scores show a risk of heart disease are more motivated to make lifestyle changes, such as losing weight and quitting smoking, than those who don't get scanned.