Acute-phase proteins and Chlamydia pneumoniae infection: which one is more important in acute coronary syndrome?

Elevated levels of acute-phase proteins, a systemic marker for inflammation, predict coronary events; Chlamydia pneumoniae (C. pneumoniae) infection is associated with coronary atherosclerosis. The present study investigated whether inflammation or infection is involved in the pathogenesis of acute coronary syndrome (ACS) and which one has the more important role. The study group comprised 49 patients with angiographically diagnosed ACS, 48 cases of chronic coronary heart disease (CCHD), and 44 subjects with a normal coronary profile. The levels of serum C-reactive protein (CRP), fibrinogen and anti-C. pneumoniae IgG antibody were measured. The IgG antibody against C. pneumoniae was higher in the ACS and CCHD groups compared with the control group after adjusting for age and gender. The levels of CRP and fibrinogen were significantly increased in patients with ACS compared with controls and CCHD patients. Multiple stepwise logistic regression analysis revealed that C. pneumoniae IgG antibody is an independent risk factor for both ACS and CCHD (odds ratio 2.3 and 2.1, respectively), but the CRP level is a risk factor only for ACS (odds ratio 6.9). The inflammatory response, as indicated by acute-phase proteins, especially CRP, rather than C. pneumoniae infection, may contribute more to the clinical course of ACS.