EDITORIAL COMMENT Chlamydia pneumoniae Infection and Coronary Artery Disease*

The possibility in recent years that chronic infection with Chlamydia pneumoniae (CPn) may represent a risk factor for atherosclerosis or a mechanism of rapid progression of ischemic heart disease, or both, has attracted the attention of investigators and clinicians all over the world. After the first description of a seroepidemiologic association between antibody titers against the intracellular bacterium CPn and coronary artery disease in 1988 (1), scientific publications (2) from both sides of the Atlantic have confirmed the initial observations. However, more recent reports, one from the U.S. (3) and another from the United Kingdom (4), have cast doubts as to the existence of a true association between CPn seropositivity and coronary events. In contrast, two other large studies also reported this year have found a strong association between immunoglobulin G (IgG) antibodies against CPn and stroke (5) and between anti–CPn IgA antibodies and mortality from ischemic heart disease (6). Thus, at present, controversy exists regarding the