A new study published in the Journal of the American Medical Association found that the addition of a patient's coronary artery calcium (CAC) score to their other risk factors for heart disease, such as smoking, age and cholesterol levels, led to a better prediction of their category of risk-low, intermediate or high-for developing heart disease than traditional factors alone. Coronary artery calcium scoring uses computed tomography (CT) to check for the buildup of calcium in plaque that can accumulate within the walls of the heart vessels. When plaque ruptures, blocking blood flow to the heart, a heart attack can occur.

A group of researchers from Northwestern University in Chicago followed study volunteers of 5,878 men and women-none of whom had cardiovascular disease at the start of the study-over six years. At the beginning of the study, each patient's heart attack risk was calculated twice, once using just the traditional risk factors and then again with the CAC score. At the end of the study, the researchers found that the addition of the CAC score was a significantly better predictor of future heart disease events that using traditional risk factors alone.

Adding the CAC score, say the researchers, moved 25 percent of the study participants into a different risk group than where they were placed based on traditional risk factors alone and had its greatest impact among patients initially thought to have an intermediate risk of developing heart disease. Among those patients, the addition of the CAC score moved 16 percent into the high-risk group and 39 percent into the low-risk group.

The researchers cautioned, however, that CAC scoring shouldn't be used for the widespread screening of every patient, but rather that it be limited to patients that fall into that gray area of intermediate risk for heart disease. For one thing, the analysis of the data didn't show how regular calcium testing actually helps people prevent future heart attacks. To show that, randomized clinical trials in which patients are divided into two groups, one that receives regular calcium testing and one that does not, would have to be done.

Plus, because coronary artery calcium testing uses a CT scan to measure calcium deposits in the arteries, patients are exposed to much more radiation than they would be during a regular X-ray, putting them at increased risk for cancer.

If you're concerned about your risk factors for developing heart disease, talk to your doctor about whether CAC scoring could be helpful to you and then weigh the benefit against your potential health risk.