AHA News Releases, March 2, 2000
Electron beam X-ray may be useful tool for predicting heart
attack risk
SAN DIEGO, March 2 – a noninvasive, high speed x-ray scan is
more accurate than relying on traditional risk factors for determining an
individual’s risk for heart disease, according to a study presented today at
the American Heart Association’s 41st Annual Conference on
Cardiovascular Disease Epidemiology and Prevention.
Conventional risk factors for heart disease include high
cholesterol levels, high blood pressure, obesity, physical inactivity, diabetes
and smoking.
Researchers found that electron beam computed tomography
(EBCT)
was significantly better than standard risk factors for categorizing heart
disease risk. However, when they combined EBCT with risk factors, such as
elevated cholesterol, their ability to assess an individual’s heart disease
risk was better than EBCT alone, says lead author Ming Wei, M.D., a clinical
epidemiologist at the Cooper Institute, a not-for-profit research center in
Dallas, Texas.
"EBCT may add significant information to conventional
risk factors for determining a patient’s level of / or risk for heart attack
and possibly even prevent heart disease from progressing in those
patients,"
Co-author Larry W. Gibbons, M.D. of the Cooper Clinic, a
medical facility associated with the Cooper Institute, adds that the
"evaluation whether EBCT scans, which typically cost $400 to $500, improved
the assessment of heart disease risk beyond what a physician could learn from a
patient’s risk factors. They studied 1,133
men and women, with an average age of 54, who received both a
risk factor assessment and an EBCT scan at the Cooper Clinic.
The researchers identified heart disease in 110 of the
patients in the study. They based their final diagnosis on the results of an
angiogram, as well as heart attacks.
Unlike conventional CT scans EBCT scans can measure calcium
deposits in heart arteries. Because EBCT obtains high–resolution images so
quickly, the pictures are not blurred like they are with conventional CT.
Because of this, EBCT can locate deposits in heart arteries that have calcified,
showing how extensive that calcification is.
Research has shown that the more calcium an individual has in
his or her heart arteries, the more likely they are to have heart disease. With
EBCT, a physician can make some judgments about how much the calcium increases a
person’s risk of a heart attack, Gibbons says.
He adds that EBCT is not designed to take the place of
angiography for providing a definite diagnosis of heart disease because it
cannot evaluate blood flow in the arteries, or show the percentage of narrowing
in a heart artery. However, the technique has attracted considerable attention
as a way to assess a person’s risk for heart disease. It has also stirred
controversy surrounding its usefulness, researchers say.
"EBCT is a useful tool for increasing our ability to
identify people at risk for heart disease," Gibbons says. " If someone
has risk factors such as a family history or diabetes, for example, this tool
might well determine the presence or extent of heart disease." Gibbons adds
that EBCT can also help physicians and patients make treatment decisions.
"If people have a history of moderately elevated
cholesterol, an EBCT scan is a great way to help them decide along with their
physicians, whether to begin taking cholesterol-lowering medication,"
Gibbons say. "If they have no calcium in their arteries, then chances are
they don’t need to be on medication. But if they are accumulating calcium in
their heart arteries, then the physician would probably decide on aggressive
medication for that patient."
Co-authors are Tedd Mitchell, M.D. and Steven N. Blair,
P.E.D.
