New study has showed that 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.
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 Chlamydia pneumoniae at some point in their lives. It spreads through the air and can cause pneumonia.
ACES researchers randomly assigned 4,012 patients with documented stable coronary artery disease to receive either once-weekly doses of Azithromycin ( Zithromax ) 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 due to coronary heart disease, nonfatal myocardial infarction, coronary revascularization, or hospitalization for unstable angina, 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 Chlamydia pneumoniae antibody.
The antibiotic treatment also had no affect on total mortality or on incidence of stroke.
Azithromycin was selected because of its proven effectiveness against the Chlamydia pneumoniae bacteria and for its once-weekly dosing.
Although antibiotic treatment of patients with clinical coronary heart disease is not helpful, the ACES study was not designed to find the role of Chlamydia pneumoniae in the cause or progression of coronary heart disease.
Different studies will be needed to determine the role of Chlamydia. pneumoniae in the early, asymptomatic development of coronary heart disease, said J. Thomas Grayston, Professor of Epidemiology, University of Washington, Seattle, the studys principal investigator.
This study was funded by the National Heart, Lung, and Blood Institute ( NHLBI ) of the National Institutes of Health ( NIH ).
The ACES results are confirmed by the similarly negative findings of the PROVE-IT TIMI 22 trial.
PROVE-IT TIMI 22 tested a different antibiotic, a fluoroquinolone, Gatifloxacin ( Tequin ) and used a different treatment schedule with participants who were somewhat younger than those in ACES and who had an acute cardiac event ( acute coronary syndrome ) at time of their enrollment in the study.
1) The New England Journal of Medicine, 2005
2) NIH, 2005