Mar. 29, 1999 WINSTON-SALEM, N.C. -- Preventing future heart attacks and strokes in people who otherwise seem healthy is the aim of a new screening test developed by researchers at Wake Forest University Baptist Medical Center.
They reported today at the American Heart Association's Epidemiology and Prevention Conference that combining a general purpose CT (computerized tomography) scan and an electrocardiogram (EKG) could yield a highly effective screening tool for blood vessel disease.
"This test could be used to help keep healthy people healthy," says Jeffrey Carr, M.D., M.S., assistant professor of radiology and public health sciences. "It has promise to be a relatively inexpensive screening tool, similar to the way mammography is used to screen women for breast cancer."
The technology measures calcium in the heart's arteries, which is a sign of atherosclerosis, the buildup of fatty deposits that can block arteries and cause heart attacks and strokes.
Determining the extent of calcium buildup may prove effective at detecting the earliest stages of heart disease and predicting the risk of a future heart attack. Currently, most people aren't tested for heart disease until they develop symptoms caused by narrowed arteries.
"If doctors could pick up high-risk people early, before symptoms develop, they could head off a heart attack at the pass," says Carr.
Another CT technology, the electron beam, has been available for more than 10 years to detect calcium in the heart's arteries. But the equipment is expensive and is available at fewer than 50 hospitals nationwide. There are more than 10,000 general-purpose CT scanners, the kind used in the new test. In a study of 36 people, Carr and his colleagues found that electron beam and general-purpose CT were equal at detecting the amounts of calcium buildup in the heart's arteries.
With the new test, an X-ray tube rotates around the body for about 35 seconds while an EKG tracks heart activity. The EKG data is used to identify 30 to 40 CT images of the heart at rest, the best time to view the coronary arteries. Viewing these clear, cross-sectional images of the heart, radiologists measure the size of calcium deposits.
Carr worked with General Electric Medical Systems to develop computer software that processes the information and produces a calcium "score." The score indicates whether vessel disease is present and helps predict the likelihood of a future heart attack.
"We know that having a score above 400, for example, means there's a high probability that the blood vessel is blocked enough to decrease blood flow," said Carr.
The results could help doctors decide which patients should have stress testing or other procedures for further diagnosis.
The new CT test is one of several potential screening tests for early cardiovascular disease. It will be evaluated along with ultrasound, magnetic resonance imaging, and other tests in a large national study funded by National Heart, Lung and Blood Institute. The Medical Center, one of only six centers in the country selected to recruit participants for the 10-year study, will follow about 2,500 to 3,000 healthy local residents.
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