Elevated Chlamydia pneumoniae antibodies, cardiovascular events, and azithromycin in male survivors of myocardial infarction

Circulation. 1997 Jul 15;96(2):404-7. doi: 10.1161/01.cir.96.2.404.

Abstract

Background: The clinical significance of the association between elevated anti-Chlamydia pneumoniae (Cp) antibody titres and coronary heart disease (CHD) is unclear. We explored the relationship between antibodies against Cp and future cardiovascular events in male survivors of myocardial infarction (MI). The effect of azithromycin antibiotic therapy was assessed in a subgroup of post-MI patients.

Methods and results: We screened 220 consecutive male survivors of MI for anti-Cp antibodies. Of these, 213 patients were stratified into three groups: group Cp-ve (n=59), no detectable Cp antibodies; group Cp-I (n=74), intermediate titres of 1/8 to 1/32 dilution; and group Cp+ve (n=80), seropositive at > or = 1/64 dilution. Patients with persisting seropositivity of > or = 1/64 were randomized to either oral azithromycin (Cp+ve-A, 500 mg/d for 3 days [n=28] or 500 mg/d for 6 days [n=12]) or placebo (Cp+ve-P, n=20). Cp+ve-NR (n=20) represented patients not recruited into the antibiotic trial. The incidence of adverse cardiovascular events (over a mean follow-up period of 18+/-4 months) was recorded and shown to increase with increasing anti-Cp titre: Cp-ve, n=4 (7%); Cp-I, n=11 (15%); Cp+ve-NR, n=6 (30%); and Cp+ve-P, n=5 (25%). Cp+ve-NR and Cp+ve-P groups had a fourfold-increased risk for adverse cardiovascular events compared with the Cp-ve group (odds ratio [OR], 4.2; 95% confidence interval [CI], 1.2 to 15.5; P=.03). In contrast, the OR for cardiovascular events in patients receiving azithromycin (Cp+ve-A, single or double course) was the same as in the Cp-ve group (OR, 0.9; 95% CI, 0.2 to 4.6, P=NS). Patients receiving azithromycin were more likely to experience a decrease in IgG anti-Cp titres than were those in the placebo group (P=.02).

Conclusions: An increased anti-Cp antibody titre may be a predictor for further adverse cardiovascular events in post-MI patients. Taking a short course of azithromycin may lower this risk, possibly by acting against Cp.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Aged
  • Anti-Bacterial Agents / administration & dosage*
  • Antibodies, Bacterial / blood*
  • Azithromycin / administration & dosage*
  • Biomarkers
  • Chlamydia Infections / blood
  • Chlamydia Infections / drug therapy
  • Chlamydia Infections / microbiology*
  • Chlamydia Infections / physiopathology
  • Chlamydophila pneumoniae / immunology*
  • Chlamydophila pneumoniae / isolation & purification
  • Humans
  • Male
  • Middle Aged
  • Myocardial Infarction / blood
  • Myocardial Infarction / microbiology*
  • Myocardial Infarction / physiopathology

Substances

  • Anti-Bacterial Agents
  • Antibodies, Bacterial
  • Biomarkers
  • Azithromycin