June 1 -- "Ultrafast CT" scanning with an
electron beam proved many times more powerful than the
best available non-invasive test in predicting heart
attacks and other coronary disease episodes, even in
apparently healthy people, a new study shows.
measuring the amount of calcium deposits that build
up in coronaries -- in a disease process commonly called
hardening of the arteries -- ultrafast CT accurately
predicts cardiovascular disease events in people with
no symptoms, doctors at St. Francis Hospital in Roslyn,
N.Y., report in today's (June 1) American Heart Association
is the first large, written report with a high degree
of completeness of follow-up (99.8%) documenting the
prospective short-term predictive value of EBCT (electron
beam computed tomography) of the coronary arteries in
asymptomatic patients," the team writes.
is a "tool that allows us to identify people who
are at high risk for coronary disease," says Yadon
Arad, M.D., the study's lead investigator and director
of preventive cardiology at St. Francis Hospital. "EBCT
screening would enable me to identify individuals in
the early stages of coronary disease who would benefit
the most from therapies (such as drug treatments, diet
and exercise) that might prevent heart attacks."
scanning costs range from $375 to $500 in the United
States, which is "relatively inexpensive, compared
to other diagnostic tests used in cardiology,"
researchers used EBCT in 1,173 asymptomatic patients
between September 1993 and March 1994 and then followed
the patients for an average of 19 months. During the
follow-up, 18 patients had a total of 26 cardiovascular
events -- including one death, seven heart attacks,
eight coronary artery bypass surgeries, nine coronary
angioplasties and one stroke.
conclude that EBCT-based screening for coronary artery
disease shows great applicability to the development
of cardiovascular disease events in a relatively short
time period (average, 19 months) in a mostly middle-aged
group that was 71 percent male," the investigators
write in Circulation.
Lewis Wexler, M.D., of Stanford University Medical Center
in California, cautions that EBCT scanning is still
undergoing clinical investigation. "As promising
as the results of the study appear to be, it's still
an experimental screening technique," he says.
"Large-scale prospective studies are needed to
prove its predictive value, which will differ depending
on a patient's age, gender and the presence of coronary
artery disease risk factors." Wexler chairs an
AHA panel that is developing a scientific statement
on coronary calcification and EBCT.
D. Guerci, M.D., study senior author and director of
research at St. Francis Hospital, says: "Our study
shows that EBCT scanning of the coronary arteries has
a predictive accuracy that exceeds by a large margin
that of any other non-invasive technology,"
cholesterol testing involves drawing a blood sample,
it's considered to be non-invasive, Guerci notes. But
even the best cholesterol test (the ratio of total cholesterol
to "good" HDL cholesterol) achieves an "odds
ratio" of only about 1.6, he says. (An odds ratio
of 1 implies no increased risk.) Guerci defines odds
ratio as "the probability of getting sick or dying
if your test result is abnormal, divided by the probability
of something bad happening to you if your test result
team found EBCT achieved odds ratios ranging from 20
to 35, making the scanning technique more than 10 times
more powerful a predictor of coronary disease episodes
than cholesterol testing, he says.
reports and other data have consistently shown a correlation
between coronary artery calcium content (CAC) and the
severity of coronary artery disease, the authors note.
EBCT provides doctors a CAC "score" for each
patient based on the amount of calcium seen in the scans.
Among study participants, CAC scores averaging 935 in
patients with coronary events, vs. scores averaging
144 in patients without events. And those individuals
with a CAC score above 160 had a 35-fold higher risk
of developing a coronary event than those with scores
below 160, the researchers found.
this is the first published report of a follow-up of
apparently healthy persons undergoing EBCT scanning
of the heart, three other studies presented at two recent
AHA scientific meetings had similar findings, Guerci
points out. "Now there are four studies with a
total of 2,745 asymptomatic patients and all four show
the coronary calcium score is highly predictive of future
the coronary arteries supply blood to the cardiac muscle
and are in constant motion as the heart beats, obtaining
X-ray images of the moving vessels was difficult until
the new superfast machines were built. Ultrafast CT
devices using electron beams now are available in about
25 cities in the United States and about 30 cities in
Europe and Asia.
emphasizes there's no link between calcium deposits
in the coronary arteries and calcium-rich foods, or
the calcium supplements taken by many older women. These
women have a high risk of developing osteoporosis and
"they should not lower their calcium intake because
of our findings," he says.
co-authors with Arad and Guerci are Louise A. Spadaro,
M.D.; Ken Goodman, M.D.; Alfonso Lledo-Perez, M.D.;
Scott Sherman, M.D., and Gail Lerner, M.S.
is one of five scientific journals published by the