Previous studies have found the bacteria Chlamydia pneumoniae in the arterial plaque of patients with coronary artery disease. Some doctors have reasoned that removal of C. pneumoniae from the system could reduce the risk of subsequent cardiac events. Prescription of antibiotics for this purpose had not been tested through a randomized clinical trial. The investigation of whether antibiotics could be used to treat the bacteria, and therefore reduce the risk of cardiac events, was conducted at 27 different sites in the United States.

All U.S. adults have been exposed to C. pneumoniae, which spreads through the air and causes pneumonia or mild repiratory disease, at some point in their lives.

This study, called the Azithromycin coronary events study, or ACES, found no benefit from treating the C. pneumoniae bacteria with an antibiotic in order to reduce the risk of heart attack or improve overall cardiac outcomes.

ACES researchers randomly assigned 4,012 men and women to receive either once-weekly doses of Azithromycin or a placebo for one year, starting in 1999. 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 antibiotic effect was shown for all participants, regardless of age, gender, smoking status, or presence of C. pneumoniae antibody. The antibiotic treatment also had no effect 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 a
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Contact: Justin Reedy
jreedy@u.washington.edu
206-685-0382
University of Washington
20-Apr-2005