The cost of a coronary calcium scan, though still not covered by insurance, has come down significantly — to about $100, in some cases — and could be of great value for millions of aging Americans at risk of life-threatening heart disease. It is one of two currently popular noninvasive X-ray techniques to assess cardiac risk and help determine who could benefit from treatments to ward off a crippling or fatal heart attack. The other test, a CT angiogram, is usually covered by insurance but is most often done only when other tests or symptoms suggest possible blockages in the arteries that feed the heart.

A cardiac calcium scan is a specialized type of low-dose X-ray that highlights calcium deposits in the plaque that can line and clog arteries feeding the heart. The more calcium, the more plaque a person is likely to have and the greater the risk of a blockage that can precipitate a heart attack if a piece of plaque breaks loose. The procedure, known as multi-slice computerized tomography, does not require that a dye be injected into the bloodstream to visualize the coronary arteries, though the findings are less precise than those from a CT angiogram, which requires a dye.

A calcium scan is most useful to assess patients considered to be at moderate risk of heart disease, as well as those whose risk is uncertain. Someone who has 5 percent to 7.5 percent chance of suffering a heart attack in the next 10 years, based on standard risk factors like age, gender, race, cholesterol level, blood pressure, smoking behavior and the presence of diabetes, is considered to be at moderate risk. The scan can also be helpful for patients deemed at low risk but with a family history of heart attack at a relatively young age, as in the case of my brother.

Dr. Mandrola, a cardiac electrophysiologist at Baptist Health in Louisville, Ky., recently reviewed both the main benefits and limitations of a cardiac calcium scan. He pointed out that the accepted nonmedical way of assessing a person’s risk of a heart attack — based on standard risk factors — is imprecise and often overestimates the risk of underlying heart disease, although it is frequently used to decide whether the patient should be taking medication, like a statin to lower cholesterol.

But when findings on a calcium scan are combined with the presence of these traditional risk factors, the result gives a clearer picture of a person’s risk of suffering a heart attack in the next decade. Also, if the calcium score is zero, it might mean the person can safely skip taking a statin or other heart-protective medication.