New Study Shows Antibiotic
Treatment Does Not Reduce Risk of Secondary Cardiac
Events
Taking antibiotics weekly for one year does not reduce
the risk of a heart attack or other cardiac event
for patients with stable coronary artery disease,
according to a study funded by the National Heart,
Lung, and Blood Institute of the National Institutes
of Health. It is published in the April 21, 2005,
edition of the New England Journal of Medicine.
Many previous studies have found the bacteria Chlamydia
pneumoniae in the arterial plaque of patients
with coronary artery disease. This led to the investigation
of whether antibiotics could be used to treat the
bacteria and therefore reduce the risk of cardiac
events. Approximately 50 percent of U.S. adults have
been exposed to C. pneumoniae at some point
in their lives. It spreads through the air and can
cause pneumonia.
“This study found no benefit from treating the
C. pneumoniae bacteria with antibiotic in
order to reduce the risk of heart attack or improve
overall cardiac outcomes,” said NHLBI Director
Elizabeth G. Nabel, M.D. “We must continue to
focus on the controllable risk factors for preventing
coronary events.”
Researchers conducting the Azithromycin and Coronary
Events Study (ACES), randomly assigned 4,012 men and
women to receive either once-weekly doses of azithromycin
or placebo for one year. After an average follow-up
of 3.9 years, there was no significant reduction of
cardiac events, defined as death, heart attack, unstable
angina, angioplasty or cardiac surgery, among participants
receiving antibiotic compared to those given placebo.
This lack of effect of antibiotic was shown for all
participants regardless of age, gender, smoking status,
or presence of C. pneumoniae antibody. The
antibiotic treatment also had no affect on total mortality
or on incidence of stroke.
Men and women were included in the study if they had
stable coronary artery disease following a previous
cardiac event such as a heart attack, angioplasty,
or cardiac bypass surgery. Azithromycin was selected
because of its proven effectiveness against the C.
pneumoniae bacteria and for its once-weekly dosing.
ACES enrolled men and women at 28 centers across the
country between 1999 and 2000. Pfizer, Inc., co-sponsored
the study and supplied study medications.
“Although antibiotic treatment of patients with
clinical coronary heart disease is not helpful, the
ACES study was not designed to find the role of C.
pneumoniae in the cause or progression of coronary
heart disease. Different studies will be needed to
determine the role of C. pneumoniae in the
early, asymptomatic development of coronary heart
disease,” said J. Thomas Grayston, M.D, Professor
of Epidemiology, University of Washington, Seattle,
the study’s principal investigator.
The ACES results are confirmed and extended by the
similarly negative findings of the PROVE-IT trial
published in the same issue of the New England
Journal of Medicine. PROVE-IT tested a different
antibiotic, a fluoroquinolone, and used a different
treatment schedule with participants who were somewhat
younger than those in ACES and who had an acute cardiac
event at time of their enrollment in the study.
For more information or to schedule an interview, please
call 301-496-4236 or email
nhlbi_news@nhlbi.nih.gov. To reach J. Thomas Grayston,
M.D., please call the University of Washington press
office at 206-543-3620.
NHLBI is part of the National Institutes of Health
(NIH), the Federal Government’s primary agency
for biomedical and behavioral research. NIH is a component
of the U.S. Department of Health and Human Services.
NHLBI press releases and other materials including
information about heart disease, heart attack, and
coronary artery disease are online at www.nhlbi.nih.gov.
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