The investigators want to study the relative effects of physical exercise vs. extended-release niacin (lipid-lowering drug) in patients with coronary heart disease and low HDL cholesterol ("good cholesterol") on

• lipid profile
• endothelial function as measured by ultrasound

The endothelium is the inner part of the blood vessels. Impaired endothelial function is known to be associated with atherosclerosis which can ultimately lead to diseases such as stroke, heart attack and others. Endothelial function can be assessed non-invasively by ultrasound.

Both interventions mentioned above have been shown to have a beneficial effect on lipid profile and endothelial function. However, the relative effects are unclear.

Comparison of physical exercise vs. extended-release niacin in patients with CAD and low HDL cholesterol (< 1,03 mmol/L) on lipid profile and endothelial function as measured by flow-mediated dilatation of radial artery. Secondary goals are the assessment of biochemical markers of atherosclerosis, expression of monocyte surface markers, oxidative stress and thrombogenicity.

Inclusion Criteria:

• Coronary disease
• Low HDL cholesterol
• Age limits (see below)

Exclusion Criteria:

• Unstable angina oder MI within 3 months prior to inclusion
• CAD with indication for bypass surgery
• Left main disease ( > 25% stenosis diameter)
• Ejection fraction < 40%
• Higher degree heart valve disease
• Higher degree ventricular arrhythmias
• Type 1 Diabetes
• Severe disorders of lipoprotein metabolism (Low-density lipoprotein cholesterol (LDL)> 5.0 mmol/L)
• Severe liver disease
• Thyroid disease
• Alcohol or drug abuse
• Pregnancy
• Stroke or Transient Ischemic Attack (TIA) within 3 months prior to inclusion
• Allergy against niacin oder other ingredient of niaspan
• Participation in other clinical trial within 30 days prior to inclusion
• Acute gastric ulcer
• Arterial bleeding
• Uncontrolled severe arterial hypertension
• Treatment with lipid-lowering drug other than Hydroxy-Methylglutaryl Coenzyme A (HMG-CoA)-inhibitor within 3 months prior to inclusion