A growing body of evidence links Chlamydia pneumoniae to the progression of coronary heart disease. The purpose of this study is to determine the positive and negative effect of 14 days treatment with clarithromycin 500 mg daily in patients already suffering from stable coronary heart disease. The participants will be followed for at least two years after the treatment.

Abbott Laboratories supplied Clarithromycin and placebo tablets.

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.

Macrolide antibiotics are effective in eradication of C. pneumoniae from atherosclerotic plaques. Two small trials showed significant beneficial effects of macrolides on cardiovascular morbidity in patients with ACS. To corroborate and extend these findings, we undertook a randomised, placebo-controlled trial with clarithromycin in patients with stable CHD in order to test the hypothesis that intervention with a macrolide would reduce cardiovascular risk with regard to mortality and morbidity.

Inclusion Criteria:

• patients aged 18 to 85 years and
• previous acute myocardial infarction (AMI) or
• previous or present angina pectoris and
• signed informed concent

Exclusion Criteria:

• AMI or unstable angina pectoris within the last three months
• revascularisation (PTCA or CABG) within the preceding six months
• severe heart failure (New York Heart Association (NYHA) functional class IV)
• known impaired renal or hepatic function
• active malignancy
• intolerance to macrolides
• treatment with methylxanthines, carbamazepine, cisapride, astemizole, terfenadine, or coumarin anticoagulants
• earlier inclusion in the CLARICOR Trial or participation in another drug trial within four weeks
• participation in other clinical trials within one month before this trial
• individuals incapable of managing own affairs or not able to sign written consent
• lack of written consent
• women of childbearing age not using reliable contraceptives
• breast feeding women