A calcium score can be a useful measure of heart attack risk

Dear Dr. Roach: You mentioned checking a calcium score to help determine risk of having a heart attack. Please explain what that is. — J.S.

Dear J.S.: A coronary artery calcium score is a kind of CT scan that looks for the presence of calcium in the arteries providing blood to heart muscle. Blockages in the arteries are usually calcified, and the scan can calculate the total amount of calcium found. The higher the calcium score, the more likely a person is to have blockages in the arteries. However, the test isn’t perfect. A person can have calcium without having any blockages, and a person may also have a cholesterol buildup that blocks flow without having calcium. It remains a useful test in certain situations.

I often use the calcium score when I am not sure whether my patient would benefit from medication therapy to reduce risk of a heart attack. This comes after a person has made the best changes they can to their lifestyle, and when they do not otherwise choose to take medication. If the calcium score is zero, then treatment may be safely deferred for five years. The risk of a heart attack in that time is very low.

Exceptions would be if a person is at high risk. In people whose heart disease risk puts them on the border of a recommendation for treatment, a calcium score above zero would tip the scales.

Calcium scores are not useful in people who are at very low risk, since they are unlikely to change the course of treatment. Patients who did not want to take a statin drug may change their mind once they receive the result of a high calcium score, but if treatment is recommended, a calcium score is not necessary.