May 2, 2002
Calcium scoring: A new technique useful for some with heart risk factors
You’ve heard a lot about controlling cholesterol to prevent heart attack, and you’ve sometimes wondered if having high blood cholesterol definitely means that you’ll have what cardiologists sometimes call an event. Thanks to a technological advance in the use of X-rays and multi-slice CT scanners, doctors can use calcium scoring to better predict the potential for heart attack in people already known to have some risk factors.
The multi-slice CT (for computed tomography) scanner uses X-rays to take a series of images of the heart very quickly to give cardiologists the best picture possible of the calcium deposits in coronary arteries. The resulting score tells cardiologists if the arteries contain too much calcium, an integral part of atherosclerotic plaque that is known to restrict the amount of blood in coronary vessels.
This better view of calcium deposits is an important new tool for cardiologists like Dr. Larry S. Dean, professor of medicine and surgery who practices at UW Medical Center.
“We’ve known for some time that people with coronary disease have some calcium in their blood vessels,” Dean says. “These newer techniques are just more sensitive. It would be very difficult to see these deposits in a regular chest X-ray. We can see them in the catheterization lab under fluoroscopy in some patients, but the CT scan is much more sensitive and less invasive.”
Calcium scoring isn’t for every patient.
“This technique has some use in patients who have several risk factors for heart disease, including high blood cholesterol, smoking, high blood pressure and a family history of heart disease,” Dean says. “This test gives us more information. Perhaps even though you have some of these risks, your calcium level is so low that we don’t see an immediate danger. Or it may indicate that calcium levels are so high that we need to recommend immediate treatment.”
Some people have very high scores, yet are free of significant heart blood vessel disease, while others with low scores have suffered major heart attacks. Nevertheless, the group with low scores tends to have only one-tenth the risk of a major cardiac event, compared to those in the high-scoring group. This 10-fold difference in predicted risk, based on the calcium score, compares with a roughly three-fold difference in cardiac events for cholesterol, smoking and high blood pressure. The calcium score appears to be a more direct estimate of the amount of plaque present in the coronary arteries than are the risk factors.
Incidentally, dropping calcium from your diet won’t change your calcium score, and can even be dangerous for post-menopausal women, who are at risk for weakened bones due to osteoporosis.
“It’s not the milk you’re drinking that’s causing the problem,” Dean says. “It’s the butterfat in the milk that’s causing the cholesterol problem, which is then causing the inflammatory process in the blood vessels. The calcium is a marker of the underlying disease process. If a patient has a high calcium score and low HDL, or so-called good cholesterol, readings, we would be much more aggressive at lowering that patient’s overall cardiac risk, through medication, exercise and diet to try to decrease the risk of heart attack.”