High prevalence of seropositivity for antibodies to Chlamydia-specific lipopolysaccharide in patients with acute coronary syndrome.

BACKGROUND: Results of recent studies have demonstrated that there is an association between infection with Chlamydia pneumoniae and coronary artery disease (CAD). Inflammatory response caused by chlamydial infection has been considered to contribute to the development of atherosclerosis in coronary arteries.

OBJECTIVE: The aim of this study was to investigate the specific relations between chlamydial infection and coronary events in patients with CAD.

METHODS: We measured serum levels of immunoglobulin A and G antibodies against Chlamydia spp.-specific lipopolysaccharide in 155 patients with CAD and 60 age-matched and sex-matched healthy controls by enzyme-linked immunosorbent assay. CAD patients were divided into groups of the patients with acute coronary syndrome [(ACS), n = 35], old myocardial infarction [(OMI), n = 60] and chronic coronary heart disease [(CCHD), n = 60].

RESULTS: Prevalence of both seropositive antibodies in the control group and CCHD group were not different. In contrast, in ACS group there were significantly higher prevalences of seropositive immunoglobulin A (46 versus 12%, P = 0.0001) and G (74 versus 45%, P = 0.005) antibodies and in OMI group there was a significantly higher prevalence of seropositive immunoglobulin A antibodies (28 versus 12%, P = 0.02). Furthermore, compared with CCHD group, in ACS group there were significantly higher prevalences of seropositive immunoglobulin A (P = 0.00006) and G (P = 0.002) antibodies and in OMI group there was a higher prevalence of seropositive immunoglobulin A (P = 0.01). Adjustment for confounding factors did not change these findings.

CONCLUSIONS: Infection with Chlamydia is significantly associated with ACS and OMI, but not with CCHD. These findings suggest that chronic and reactive infection with Chlamydia can lead to disruption of vulnerable plaque in patients with ACS.