RESUMO
BACKGROUND: Recent studies have suggested a possible association between Chlamydia pneumoniae infection and coronary heart disease. OBJECTIVES: To determine titers of antibodies to C. pneumoniae in patients with acute myocardial infarction compared with titers in several control groups. METHODS: This prospective case-control study investigated 209 individuals. We assessed the serum IgG antibody titers to C. pneumoniae in 57 consecutive patients admitted with AMI to our intensive coronary care unit during a 4 month period. A serum sample was drawn upon admission and after 6 weeks. Results were compared with those of four control groups: a) patients admitted with community-acquired pneumonia (n = 18), b) patients with community-acquired urinary tract infection (n = 42), c) patients with angiographically normal coronary artery disease (n = 44), and d) patients with stable coronary artery disease (n = 48). Serum immunoglobulin G antibody titers to C. pneumoniae were determined using standard micro-immunofluorescence technology. RESULTS: Of 57 patients with AMI, 32 (56%) had a high IgG titer to C. pneumoniae (> or = 1:256) on the initial test, which remained unchanged (62%) after 6 weeks. The percentage of patients with high titers was significantly lower in the control groups: 5 of 18 patients (28%) in the pneumonia group (P < 0.01), 11 of 42 (26%) in the urinary tract infection group (P < 0.01), 11 of 44 (25%) with normal coronary arteries (P < 0.01), and 17 of 48 (35%) with stable chronic ischemic heart disease (P < 0.05). CONCLUSION: The detection of high titers of IgG antibodies to C. pneumonia in many patients with AMI, compared to control groups, suggests that chronic Chlamydia pneumoniae infection plays a role in the pathogenesis of atherosclerosis and acute ischemic events.