Largest Study to Date Examines CT Scanning for Prevention of Heart Disease

Calcium deposits in coronary arteries are a strong predictor for possible future heart attacks and cardiac diseases, and detecting such deposits can be valuable for promoting overall cardiac health, according to a new study utilizing computed tomography (CT) scanning.

Supported by the U.S. National Institutes of Health (NIH; Bethesda, MD, USA), the study, led by researchers from the University of California (UC), Irvine (USA) and appearing in the March 28, 2008, issue of the New England Journal of Medicine (NEJM) is the largest involving CT scanning to date--testing some 6,700 people in the United States. It is also the first study to include racially and ethnically diverse participants. Previous coronary calcium studies featured only small enrollments of white patients.

"The results prove that coronary calcium detection is a strong predictor of heart attack and disease for African Americans, Hispanics, and Chinese Americans as well,” said Dr. Robert Detrano, professor of radiological sciences at UC Irvine and study leader. "It wasn't known before whether this would be effective for other racial and ethnic groups, and this study answers that important question.”

Coronary calcium is detected by CT scanning; a noninvasive procedure that, for calcium identification, does not require injected contrast. The procedure focuses on the coronary arteries, which supply blood to the heart and are particularly vulnerable to calcium buildup. The researchers discovered that participants with moderate deposit amounts had more than a seven times greater risk of cardiac heart disease compared to people with no coronary calcium buildup. Participants with large deposit amounts faced a 10 times greater risk.

Coronary calcium is a marker for a diseased artery. It accumulates similar to atherosclerotic plaque and is caused by the same primary factor--high blood lipid levels. According to Dr. Detrano, calcium screening can be recommended for people who are at moderate risk. "This is a very practical and effective method for cardiac disease and heart attack prevention,” stated Dr. Detrano, who had proposed the study of calcium screening as early as 1989. "One of the factors we need to address is cost; it behooves the imaging industry to bring the cost down and make this procedure available to everyone.”

According to Dr. Detrano, the current cost for a CT scan is between US$300 and $600 per exam. However, he believes that costs can be lower. In his work diagnosing and treating cardiac diseases in rural China, Dr. Detrano performs CT research scans for as little as $30.

Detrano added that these results also contribute to his clinical efforts in China. Before the study, he said, it had not been established that coronary calcium detection could predict future cardiac diseases and heart attacks in Chinese people. Through UC Irvine and the China-California Heart Watch, a not-for-profit organization of which he is president, Dr. Detrano leads clinical efforts in poor rural regions of southern China where cardiac care is deficient or nonexistent.

For the study, Dr. Detrano and his colleagues performed coronary calcium scanning on 6,722 men and women at U.S. sites in Los Angeles, CA; New York City, NY; Baltimore, MD; Chicago, IL; St. Paul, MN; and Forsythe County, NC. Thirty-nine percent of the participants were Caucasian, 28% African-American, 22% Hispanics, and 12% Chinese. Participants entered the study without cardiovascular disease and they were followed for an average of 3.8 years.


Related Links:
University of California, Irvine
China-California Heart Watch