NEJM: Calcium CT scans help predict coronary risk across racial, ethnic lines

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A coronary artery calcium (CAC) score gathered from a cardiac CT scan is a strong predictor of incident coronary heart disease (CHD) and provides predictive information beyond that provided by standard risk factors indicating no major differences between the four major racial and ethnic groups in the United States, according to a study published in the New England Journal of Medicine (NEJM).

Robert Detrano, MD, from the department of radiological sciences at University of California at Irvine, and colleagues had observed that in white populations, CT measurements of CAC predict CHD independently of traditional coronary risk factors. The researchers undertook the study to determine whether CAC predicts CHD in other racial or ethnic groups.

The investigators collected data on risk factors and performed scanning for CAC in a population-based sample of 6,722 men and women, of whom 38.6 percent were white, 27.6 percent were black, 21.9 percent were Hispanic and 11.9 percent were Chinese. The study subjects had no clinical cardiovascular disease at entry and were followed for a median of 3.8 years, the authors wrote.

Detrano and colleagues were 162 coronary events, of which 89 were major events (myocardial infarction or death from CHD).

In comparison with participants with no coronary calcium, the researchers found that the adjusted risk of a coronary event was increased by a factor of 7.73 among participants with CAC scores between 101 and 300 and by a factor of 9.67 among participants with scores above 300.

Among the four racial and ethnic groups, a doubling of the calcium score increased the risk of a major coronary event by 15 to 35 percent and the risk of any coronary event by 18 to 39 percent, according to the investigators.

The researchers also found that the areas under the receiver-operating-characteristic curves for the prediction of both major coronary events and any coronary event were higher when the calcium score was added to the standard risk factors.

According to Forbes, a calcium scan using CT costs $300 to $600; and the scan is a potential competitor for much less expensive tests for coronary risk, such as blood cholesterol and blood pressure readings.

“It is mostly an issue of cost,” said William S. Weintraub, MD, chief of cardiology at the Christiana Health Care System in Newark, Del., who wrote an accompanying editorial in the NEJM. “It does add to our discrimination, but it costs a couple of hundred dollars and we're not sure how you use it.”