CT scan for calcium helps detect heart disease

By Cherry Sokoloski
Fossil Creek Current

Because of technological advances, doctors now have a valuable new tool for early detection of coronary artery disease.

It's a specialized type of CAT scan, called cardiovascular CT. Many patients with a family history of heart disease or other risk factors are opting to have this test done to assess the health of their coronary arteries.

In brief, the test measures calcium in the coronary arteries. Calcium is necessary and good when it's in bones and teeth; it's not good when it builds up in arteries.

If a person develops coronary atherosclerosis, calcium combines with cholesterol and other cellular elements to form a substance known as plaque. In layman's terms, atherosclerosis is known as "hardening of the arteries." Plaque essentially reduces the size of arteries, restricting blood flow in the body. When plaque clogs coronary arteries, it reduces the amount of blood that can flow to the heart.

If insufficient blood and oxygen reach the heart, the patient may experience chest pain or angina. If the blood supply cannot reach the heart at all, the patient experiences myocardial infarction, or a heart attack.

Plaque: two types

There are two types of plaque, hard and soft, and both are dangerous. Hard plaque describes atherosclerosis containing calcium. Soft plaque describes atherosclerosis without calcium deposits. Both can cause narrowing of the heart arteries and possibly lead to a heart attack.

A cardiovascular CT noncontrast "calcium scan" can detect hard or calcified plaques. A high calcium score indicates that hard plaque is present.

What about soft plaques? Dr. Patrick Green, a cardiologist with the Heart Center of the Rockies in Fort Collins, said that when hard plaque is present in the coronary arteries, soft plaque is there as well. On the flip side, if the cardiovascular CT shows no hard plaque, soft plaque could still be present; however, the risk of imminent cardiac events should generally be low.

"A cardiovascular specialist can help with the interpretation of results," noted Dr. Green.

At-risk groups

"A person might consider getting a CT calcium score if he or she has a significant family history of CAD," Dr. Green stated. Other heart-disease risk factors such as hypertension, high cholesterol, diabetes, smoking, men over 40 and women over 50 may prompt patients or their doctors to ask for the test.

Dr. Green said a noncontrast CT calcium score costs about $300. Locally, this type of CT scan is performed only at the Imaging Center, which has facilities at the Poudre Valley Hospital Harmony Campus and at Medical Center of the Rockies. While CT scans for the entire body have been used for many years, this type of diagnostic imaging of the heart was developed only recently. The CT calcium score is an extremely fast scan, a necessity since it must render images of a beating heart.

Besides its relatively low cost, the CT calcium score has a few other advantages. It is noninvasive and painless, and it doesn't require injections or special preparation, such as fasting or drinking special fluids. The test usually takes 20 to 30 minutes.

Another scan used to measure CAD is the CT coronary angiogram. This test requires the intravenous administration of a "contrast" substance that allows doctors to visualize the coronary artery better and determine if significant blockage is present (both soft and hard plaque). This test, which is also noninvasive, costs about $700, according to Dr. Green. When an angiogram is done, it is generally accompanied by a calcium-scoring test.

Dr. Green noted that neither private insurance nor Medicare covers a CT calcium scan. A CT coronary angiogram is sometimes covered by insurance, especially when it will avoid a more expensive invasive coronary angiogram.

The CT calcium scoring test is just one of many tests used to detect coronary artery disease.

"The good news is we have several different types of stress tests and ways to image the heart," said Dr. Green. "The bad news is there is no 'one perfect test' that will provide all the information we need when managing patients with coronary artery disease."

Some people will need a combination of tests, he added, and some tests are better than others in certain situations. "A cardiovascular specialist can help sort through these scenarios," he noted.

For most patients who have plaque in the coronary arteries, Dr. Green recommends cholesterol lowering and a daily dose of aspirin. For everyone's heart health, he promotes smoking cessation, a healthy diet and regular exercise.