Antibiotics for the secondary prevention of ischemic heart disease - A meta-analysis of randomized controlled trials

Background: Infections have been suspected in the pathogenesis of ischemic heart disease (IHD) for more than 106 years. Chlamydia pneumoniae has been identified in atherosclerotic specimens, and in some studies antibody titers to C pneumoniae have been related to the risk of myocardial infarction. The numerous clinical trials that have studied the use of antibiotics in the secondary prevention of IHD have had conflicting results. Methods: This study is a meta-analysis of the published randomized controlled trials on the secondary prevention of IHD with antibiotics. Studies included in the analysis were limited to those studies that used antibiotics effective against C pneumoniae, enrolled patients with known IHD, and examined clinical outcomes related to IHD. Inclusion in the analysis was limited to well-designed randomized controlled trials that met inclusion criteria established by an expert panel. Results: Nine published studies, with a total of 11015 participants, were identified that met the criteria for this meta-analysis. Four of the studies reported a benefit from antibiotics, whereas 5 found no effect. A funnel plot of the published studies did not suggest the existence of other unpublished data. The combined effect found no benefit from antibiotics in the prevention of cardiovascular events in subjects with known IHD (relative risk, 0.94 [95% confidence interval, 0.86-1.03]) or mortality (relative risk, 0.94 [95% confidence interval, 0.79-1.12]). Conclusion: In patients with known IHD, macrolide antibiotics for C pneumoniae did not result in a statistically significant reduction in recurrent cardiac events or mortality over 3 months to 3 years.