Basic science suggests a fundamental role for inflammation in mediating all stages of coronary heart disease (CHD), and a large number of clinical studies have reported an association between markers of inflammation and CHD. Consequently, infectious agents have been proposed as promoters of atherosclerosis and/or acute coronary syndrome (ACS). Many studies have suggested a relation between Chlamydia pneumoniae (C. pneumoniae) infection and CHD, and C. pneumoniae has been demonstrated in atherosclerotic tissue.