Dual role of infections as risk factors for coronary heart disease

AIMS: The aim of the study was to explore whether exposure to microbial agents determines the prevalence of acute coronary events. METHODS AND RESULTS: Patients with unstable angina pectoris and myocardial infarction (N=335) and their paired controls were investigated. The subjects answered a questionnaire about their childhood contagious diseases: varicella, scarlet fever, measles, rubella, mononucleosis and mumps. Blood samples were taken for bacterial and viral serology. The odds ratio for CHD was highest in the upper quartile of the enterovirus (EV), herpes simplex virus (HSV) and Chlamydia pneumoniae HSP60 IgG antibody titers (1.86, p=0.001, 1.57, p<0.048 and 1.70, p=0.016, respectively). The antibody titers increased cumulatively the risk for CHD (odds ratios 1.89, 2.24, 3.92 and p-values <0.001, 0.001 and 0.047). Childhood contagious diseases (n=6) had a protecting effect against CHD (odds ratio 0.86, p=0.013). The risk for acute coronary events decreased significantly with increasing number of childhood contagious diseases (p=0.007). CONCLUSIONS: Infections have a dual role in the genesis of CHD. EV, HSV and C. pneumoniae heat shock protein 60 IgG antibodies are associated with increased risk for CHD. Protection from infections usually suffered during the childhood before the era of MMR vaccination may predispose the individual to CHD.