The purpose of this study is to investigate whether there is a difference in endothelial function, heart rate variability and carotid intimal media thickness in patients with coronary artery disease who are receiving fish oil therapy.

One hundred patients with established coronary artery disease by coronary angiography will undergo randomization for enrollment in the study. Baseline evaluation will include assessment of brachial artery endothelial function, heart rate variability and carotid intimal media thickness. Evaluation of the endothelial function of the brachial artery will be elucidated by inflation of a blood pressure cuff around the arm for five minutes and measuring blood vessel dynamics after release of the cuff. Heart rate variability will be evaluated by 24 hour holter monitoring and analysis by standard protocol. Carotid intimal media thickness will be evaluated by ultrasound measurements guided by predetermined protocol. Patients will then be randomized to a highly purified fish oil, Omacor, 1 gram twice a day or placebo. Brachial artery ultrasound and holter monitoring will be repeated at 2 months. Carotid ultrasound will be repeated at the end of the study at 12 months.

Inclusion Criteria:

1. Established coronary artery disease as determined by coronary angiography within the last 5 years demonstrating at least 50% stenosis in one of the major coronary vessels
2. Age >18 and <75.

Exclusion Criteria:

1. Baseline fish oil intake ≥1g/day or fish intake >100g/day
2. Need for urgent or emergent CABG
3. Contraindication for plavix, aspirin or statin
4. Gastrointestinal malabsorption syndrome
5. Pregnancy
6. Oral contraceptive use
7. Ejection fraction <40%
8. Underlying atrial or ventricular arrhythmia
9. History of rheumatoid arthritis