Recent research points to calcium deposits on the walls
of coronary ateries as a predictor of heart problems.
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Calcium Deposits May Predict Heart Problems
(May 12) -- Roughly half of all heart attacks and other
coronary deaths occur in people without symptoms of
heart disease. A new and somewhat controversial
screening method that measures calcium deposits in the
walls of the arteries that cover the heart offers the
promise of predicting these events in this group of
hard-to-identify patients.
In the largest study ever published assessing electron
beam coronary artery calcium scanning as a screening
tool for heart disease, researchers concluded that the
diagnostic method was remarkably useful for identifying
future trouble in people at moderate risk. Compared with
men with the lowest levels of the calcium deposits in
the coronary arteries, men with the highest levels of
calcium scores were twice as likely to have heart
attacks and 10 times as likely to need bypass surgery or
angioplasty.
"Electron beam tomography (EBT) provided incremental
information above the traditional risk factor assessment
for this intermediate risk group," lead researcher
George T. Kondos, MD, tells WebMD. "This appears to be
much better than the traditional treadmill test for
identifying people with asymptomatic disease."
In this study, Kondos and colleagues at the University
of Illinois College of Medicine used EBT to evaluate the
risk for coronary events among 5,635 men and women with
no symptoms of heart disease. Participants were asked to
hold their breath on two occasions for 30 seconds to one
minute while lying on a special couch that slid into a
hollow computed tomography (CT) scanner. During this
time, electron beams create multiple images of the
heart, and a computer measures the density of calcium
deposits in the artery walls.
Within three-and-a-half years of having the test, 224 of
the volunteers developed evidence of heart disease. They
either required bypass surgery or angioplasty to open
clogged arteries, had heart attacks, or died of
coronary-related causes. EBT scanning detected high
amounts of calcium deposits in 95% of these
participants, but low amounts of calcium were detected
in 67% of the participants who did not experience
coronary events.
Compared with people with the lowest calcium levels,
women with the highest levels were almost four times as
likely to need heart bypass surgery or angioplasty
during the follow-up, and men were 10 times as likely to
require the procedures.
Kondos tells WebMD that EBT probably has little value in
predicting future heart disease in people at very low or
high risk for heart disease. Those at intermediate risk
-- including men over 45 and women over 50 with at least
one added risk factor, such as diabetes, high blood
pressure, high cholesterol, family history, or vascular
disease -- would benefit from this screening.
"This study reinforces (the idea) that the test is best
reserved for individuals at intermediate risk in the
population," American Heart Disease President Robert
Bonow, MD, says in a news release.
In an editorial accompanying the study, cardiologist and
epidemiologist William Weintraub, MD, wrote that it is
clear that the cost of EBT can not be justified for
people at high and low risk for heart disease. The
10-minute test can cost from $400 to $1,000 and it is
rarely covered by insurance.
The jury is still out, he concludes, on whether the cost
is justified in people in the intermediate-risk
category. Critics of the scanning method say another new
measure of heart disease risk -- blood testing for the
presence of C-reactive protein -- may prove to be just
as useful at a fraction of the cost.
Weintraub, who is a professor of medicine at Atlanta's
Emory University, tells WebMD that he would recommend
EBT as a diagnostic test for some, but not all, people
in the intermediate-risk category.
"This is a powerful predictor of risk, but we are not
quite sure what it adds to the other risk factors that
we already measure," he says. "Within the next five
years I do think it will have a bigger place in the
diagnosis of coronary artery disease and its position
will be better defined."
SOURCES: Circulation, May 27, 2003. George T. Kondos,
MD, associate professor of medicine, associate chief of
cardiology, University of Illinois at Chicago College of
Medicine. William S. Weintraub, MD, professor of
medicine, Emory University, Atlanta.
© 2003 WebMD Inc. All rights reserved. |
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