A nested case-control study of the association between Chlamydia pneumoniae and cytomegalovirus and coronary heart disease

Despite the progress in prevention, diagnosis, and treatment, coronary heart disease still remains the leading cause of death in the United States, and established risk factors are unable to explain fully half of all coronary heart disease cases. This study addresses the hypothesis that previous Chlamydia pneumoniae or cytomegalovirus infection is a significant independent risk factor for coronary heart disease.; Data and specimens were collected from a well-established prospective cohort of United States Military active-duty personnel. A nested case-control study was conducted using 300 cases and 300 matched controls. Cases were male, 30–50 years of age, with a medically documented first time hospitalization for acute myocardial infarction and a serum specimen drawn at least one year prior to the time of the acute myocardial infarction. Population-based controls were chosen from the same cohort and individually matched on age, race, and time of specimen collection. Controls had no record of hospitalizations due to cardiovascular reasons prior to the date of the case event. Evidence of past infection with C. pneumoniae was measured using microimmunofluorescence and cytomegalovirus was measured using enzyme immunoassay.; No independent risk of acute myocardial infarction was associated with Chlamydia pneumoniae IgG or cytomegalovirus IgG. Significant risk, adjusted for age, education, and marital status, was noted in the 300 matched case-controls pairs for high titers to Chlamydia pneumoniae IgA (RR_adj = 1.72, 95% CI 1.06–2.78). Using a subset of 183 cases and controls for whom cardiovascular risk factors were known, the relative risk adjusted for demographics, hypercholesterolemia, smoking and stress was 1.61 (95% CI 0.89–2.97). The risk associated with high titers to Chlamydia pneumoniae IgA was greatest in specimens collected within five years of the case event (RR_adj = 2.08, 95% CI 1.05–4.13).; Results of this study demonstrate a significant association between high titer antibody to Chlamydia pneumoniae IgA and acute myocardial infarction, but no independent association between Chlamydia pneumoniae IgG or cytomegalovirus IgG and acute myocardial infarction. An important challenge is to identify new modifiable risk factors for coronary heart disease, which could be used in prevention strategies to reduce the morbidity and mortality associated with coronary heart disease.