Calcium Scans Help Predict Coronary Risk
WEDNESDAY March 26, 2008 -- Scanning the heart arteries for calcium deposits can help predict future cardiac problems, a new study shows, but experts aren't sure that adding such scans to routine checkups would be worth the cost.
"It has been shown to be predictive" of potential heart trouble, said Dr. Diane Bild, deputy director of the division of prevention and population sciences at the U.S. National Heart, Lung, and Blood Institute, which funded the study. "Whether it is actually beneficial to the people who are screened has not been shown."
A calcium scan using computed tomography (CT) costs $300 to $600. These scans look for calcification -- hardening of the arteries caused by high blood fats and calcium deposits that can eventually cause blood vessel blockage. The scan is a potential competitor for much less expensive tests for coronary risk, such as blood cholesterol and blood pressure readings.
The new study involved more than 6,700 American men and women across a number of racial and ethnic groups -- white, black, Chinese, Hispanic -- who were followed for an average of 3.8 years. It found that the risk of a coronary event was nearly 10 times higher for those with the highest calcium deposit scores than for those with the lowest.
"This study was launched in 1999, a time when there was a lot of interest in whether this new test could predict coronary artery disease," Bild said. "A lot of studies have been done in predominantly white populations. This was one of our efforts to include minority groups."
The study does show that calcium scanning "modestly improves predictions over traditional risk factors," she said. "Several pieces of information are needed in order to understand whether this is clinically useful."
The findings are published in the March 27 issue of the New England Journal of Medicine.
The cost of such scans could be reduced, according to a statement from study lead author Dr. Robert Detrano, professor of radiological sciences at the University of California, Irvine, who is traveling in China. Scans have been done for just $30 in China, Detrano noted.
"It is mostly an issue of cost," said Dr. William S. Weintraub, chief of cardiology at the Christiana Health Care System, the largest health-care system in Delaware, who wrote an accompanying editorial in the journal. "It does add to our discrimination, but it costs a couple of hundred dollars and we're not sure how you use it."
Reducing the cost would make the test more usable, and "more epidemiological studies showing its value in risk prediction would be of great value," Weintraub said.
"But I'd be uncomfortable now with the idea of recommending this for everybody, or even defining a middle ground where we are unsure how we treat people so they get this first," he said.
A calcium scan also carries some risk, since it exposes a person to radiation, Bild noted. "It would be worth it if the benefit outweighed that risk," she said. "We don't clearly have both sides of that equation established."
For more on coronary calcium scans, visit the U.S. Heart, Lung, and Blood Institute.
Posted: March 2008