Chlamydia preumoniae in ischemic heart disease

Background: Previous work has suggested an association between Chlamydia pn eumoniae infection and coronary artery disease. The infection was demonstra ted by titers of antibodies - enzyme-linked immunosorbent assay or immunofl uorescence, and polymerase chain reaction - and by the findings of C. pneum oniae in the atherosclerotic plaque. Objectives: To evaluate the association between chronic infection with C. p neumoniae, as measured by a high titer of IgG antibody, and CAD. Our study was designed to explore the relationship between seropositivity to C. pneum oniae and serious coronary events, and to assess whether or not there may b e an additional association between established cardiovascular factors and infection with this organism. Methods: The serum of 130 patients with proven CAD was tested for the prese nce of IgG antibodies to C. pneumoniae using an ELISA test. A titer <1:64 u sing the microinfluorescence method, the recognized "gold standard," correl ates with a positive result when using the ELISA method. The mean age was 5 7 (40-65 years). The patients, 82% male and 18% female, had either myocardi al infarction (n=109) or unstable angina (n=21) 6 months before the investi gation (range 3-24 months). The serum for the control group was obtained fr om 98 blood donors from the same area matched for age 52 (40-58 years) and sex. The donors had no known cardiac history. Results: In the CAD group 75% of patients were positive for C. pneumoniae c ompared to 33% in the control group (P=0.001). No increased correlation cou ld be demonstrated between traditional risk factors and C. pneumoniae infec tion, except in those patients with diabetes mellitus. We found a lower pre valence of IgG antibody to C. pneumoniae in the diabetes subgroup than in o ther subgroups (P<0.006), but a higher prevalence than in the control group . Conclusions: We demonstrated a more than twofold increase in seropositivity to C. pneumoniae among patients suffering serious coronary events, and thi s trend was independent of gender, age or ethnic group. These findings sugg est that chronic C. pneumoniae infection may be a significant risk factor f or the development of CAD, but this correlation should be investigated furt her.