Clinical Study On The Relationship Between Chlamydia Pneumoniae Infection And Coronary Artery Disease

Coronary artery diease (CAD) contributes great menace to the middle-aged and the eldly people. Its etiology is complicated and has not been clearly defined yet. Chlamydia pneumoniae has been associated with CAD in recent years. However, whether or not Chlamydia pneumoniae is a cause of CAD still needs to be determined. Few prospective clinical studies regarding the relationship between Chlamydia pneumoniae and CAD had been published in China. Only a few epidemiologic studies and a small-scale antibiotic intervention trial have been reported. If the hypothesis that Chlamydia pneumoniae is one cause of CAD would be proven, a new strategy about CAD treatment will come to clinical use and the prognosis of many patients will be expected to improve. In our present study, in order to determine whether Chlamydia pneumoniae is a cause for atherosclerosis, we establish Chlamydia pneumoniae detection methods, investigate the prevalence of Chlamydia pneumoniae infection among patients with CAD and conduct a randomised double blind placebo-controlled azithromycin intervention trial among CAD patients with or without Chlamydia pneumoniae infection to evaluate whether antimicrobial therapy would reduce cardiovascular events. Part Ⅰ. Establishment of method for Chlamydia pneumoniae detection We used microimmunofluorescence (MIF) for the detection of serum Chlamydia pneumoniae IgG, IgA and IgM. The method proved to be easy to carry out, and the result was replicable. It was a recommended method for epidemiologic study. We had also developd a nested-PCR for the detection of Chlamydia pneumoniae DNA in peripheral blood mononuclear cell. The mothed proved to be highly sensitive and specific for Chlamydia pneumoniae.Part Ⅱ. Investigation of Chlamydia pneumoniae infection in patients with coronary artery disease The acute infection rates as diagnosed by serological test were 8.8% in CAD patients and 3.7% in non-CAD controls (p=0.330). Chronic infection rates were 47.8% vs 20.4% (p<0.001). The total of acute and chronic infection rates were higher in CAD patients than in non-CAD controls, which were 56.6% and 24.1% (p<0.001), respectively. Most of patients infected with Chlamydia pneumoniae did no have any obvious clinical symptoms. The Chlamydia pneumoniae DNA positive rates were 13.5% in CAD patients and 3.7% in non-CAD controls (p=0.042).The serological diagnosed acute and chronic infection rates plus DNA positive rates were 63.3% in CAD patients, higher than 24.1% in non-CAD controls (p<0.001).Serological study revealed that the IgG titer against Chlamydia pneumoniae was higher in CAD patients than in non-CAD controls. The percentages of IgG≥64 in CAD patients and in non-CAD controls were 71.7% vs 35.2% (p<0.001), respectively. IgG geometric mean titer were 68.9 vs 37.3 (p<0.001), respectively.The percentages of IgA≥32 in CAD patients and in non-CAD controls were 37.5% vs 18.5% (p=0.008), respectively. IgA geometric mean titers were 16.0 vs 13.4(p=0.095), respectively. The percentages of IgM≥16 were 1.2% in CAD patients and 0% in non-CAD controls (p=1.00).After correcting common risk factors of CAD, Chlamydia pneumoniae IgG ≥64 (OR=2.04, OR95%CI: 1.41~2.95) was an independent factor. Our data suggested that Chlamydia pneumoniae infection might be associated with CAD. Part Ⅲ. Randomised double blind placebo controlled azithromycin intervention trial in patients with CADAccording to the results of Chlamydia pneumoniae antibody and DNA detection, a total of 234 CAD patients were divided into infection (n=149) and non-infection group (n=85). 74 patients in infection group were randomized to azithromycin and 75 to placebo. 42 patients in non-infection group were assigned to azithromycin and 43 to placebo. 216 patients were evaluable for endpoint events and laboratory test change during one year. At baseline, the general information, basic medications and laboratory tests were comparable between azithromycin and placebo group.During one year of follow-up, of 216 patients evaluble, 29 (...