Risk of Heart Attack Not Reduced by Antibiotics

A new study has shown that taking antibiotics for a year does not reduce the risk of a heart attack or other cardiac event in patients with stable coronary artery disease.

Since previous studies found the bacteria Chlamydia pneumoniae in the arterial plaque of patients with coronary artery disease, researchers wondered whether antiobiotcs could be used to treat the bacteria and thereby reduce the risk of cardiac events. About 50% of U.S. adults have been exposed to C pneumoniae sometime in their lives.

The researchers 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 heart attack, unstable angina, angioplasty, or cardiac surgery among participants who received the antibiotic compared to those given placebo. The treatment also showed no affect on total mortality or on the incidence of stroke. The men and women in the study had stable coronary artery disease following a previous cardiac event such as a heart attack, angioplasty, or bypass surgery.

"Although antibiotic treatment of patients with clinical coronary heart disease is not helpful, the ACES [Azithromycin and Coronary Events Study] study was not designed to find the role of C pneumoniae in the cause or progression of coronary heart disease,” explained J. Thomas Grayston, M.D., professor of epidemiology, University of Washington (Seattle, USA), and the study's principal investigator.

The study was funded by the U.S. National Heart, Lung, and Blood Institute (Bethesda, MD, USA), and the results were reported in April 21, 2005, issue of The New England Journal of Medicine.




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