Chlamydia pneumoniae but Not Cytomegalovirus Antibodies Are Associated With Future Risk of Stroke and Cardiovascular Disease

Background and Purpose —Several cross-sectional and prospective studies have indicated that high titers of antibodies to Chlamydia pneumoniae and cytomegalovirus (CMV) are associated with coronary heart disease. The aim of the present study was to examine whether elevated titers of antibodies to these pathogens are predictive of not only coronary but also cerebrovascular disease. Methods —Serum titers of antibodies to C pneumoniae (IgM, IgG, IgA, IgG immune complex) and CMV (IgG) were determined at baseline (n=130) and after 3.5 years (n=111) in a total sample of 152 men. All individuals had treated hypertension and at least 1 additional risk factor for cardiovascular disease (hypercholesterolemia, smoking, or diabetes mellitus) and constituted 93% of a randomly selected subgroup (n=164) of patients participating in a multiple risk factor intervention study. Results —Elevations of any or both of the IgA or IgG titers to C pneumoniae at entry or after 3.5 years were found in 84 cases (55%). Of those with high titers at entry, 97% remained high at the 3.5 year reexamination. After 6.5 years of follow-up, high titers to C pneumoniae at entry were associated with an increased risk for future stroke (relative risk [RR], 8.58; P =0.043; 95% CI, 1.07 to 68.82) and for any cardiovascular event (RR, 2.69; P =0.042; 95% CI, 1.04 to 6.97). A high serum titer of antibodies to CMV was found in 125 cases (85%), and this was not associated with an increased risk of future cardiovascular events. Conclusions —Seropositivity for C pneumoniae, but not for CMV, was associated with an increased risk for future cardiovascular disease and, in particular, stroke.