Infections, inflammation, and the risk of coronary heart disease

Background-The role of infections and inflammation in the pathophysiology o f coronary heart disease is emerging, We studied the independent and joint effects of these 2 components on coronary risk. Methods and Results- We measured baseline levels of C-reactive protein (CRP ) and antibodies to adenovirus, enterovirus, cytomegalovirus, and herpes si mplex virus as well as to Chlamydia pneumoniae (Cpn) and Helicobacter pylor i in 241 subjects who suffered either myocardial infarction or coronary dea th during the 8.5-year trial in the Helsinki Heart Study, a coronary primar y prevention trial. The 241 controls in this nested case-control study were subjects who completed the study without coronary events. Antibody levels to herpes simplex type I (HSV-1) and to Cpn were higher in cases than in co ntrols, whereas the distributions of antibodies to other infectious agents were similar. Mean CRP was higher in cases (4.4 versus 2.0 mg/L; P<0.001), and high CRP increased the risks associated with smoking and with high anti microbial antibody levels. The odds ratios in subjects with high antibody a nd high CRP levels were 25.4 (95% CI 2.9-220.3) for HSV-1 and 5.4 (95% CI 7 .1-12.4) for Cpn compared with subjects with low antibody levels and low CR P. High antibody levels to either HSV-1 or to Cpn increased the risk indepe ndently of the other, and their joint effect was close to additive. Conclusions-Two chronic infections, HSV-1 and Cpn, increase the risk of cor onary heart disease, The effect is emphasized in subjects with ongoing infl ammation, denoted by increased CRP levels.