The primary goal of this study is to assess the safety of Plexisyl-AF administered by direct application to the cardiac fat pads in patients undergoing coronary artery bypass grafting. Secondary goals of the study are to assess the potential response of Plexisyl-AF to reduce the occurrence of postoperative atrial fibrillation and assess the performance of the electrostimulator device to confirm the location of the epicardial fat pads (nerves). The occurrence of postoperative atrial fibrillation will be monitored by continuous cardiac monitoring.

The purpose of this study is to investigate a non-surgical and non-destructive approach to providing a temporary, protective parasympathectomy as a means to reducing postoperative atrial fibrillation following cardiac surgery. Applications of Plexisyl-AF will be placed in the cardiac fat pads as a means for creating a "non-destructive" cardiac denervation.

This is a randomized assessment to demonstrate the safety of Plexisyl-AF in patients undergoing open heart surgery. Eligible patients will be those submitted to undergo open-chest CABG. Patients will receive Plexisyl-AF, administered via direct application to the SA nodal and AV nodal epicardial fat pads during the surgical procedure.

Patients will be monitored for the occurrence of atrial fibrillation via the use of continuous cardiac monitoring for a period of 120 hours following surgery. Patients will return the clinic for brief follow-up, including electrocardiographic recordings, 10 days, 30 days and 90 days after the date of surgery.

Inclusion Criteria

1. The patients must be able and willing to give written informed consent.
2. The patients will be adult (age ≥ 18 years and </= 70 years) males or females who are scheduled to undergo on-pump open-chest coronary artery bypass grafting surgery of two (2) or more arteries.
3. The patients should be effectively treated prior to enrollment with an appropriate medical regimen (such as aspirin, ß-blockers, nitrates, and ACE inhibitors). Changes to medications after enrollment should be avoided.
4. If female, the patients must be (a) post-menopausal, (b) surgically sterile or (c) using adequate birth control and have a negative pregnancy test within 7 days prior to administration of device.

Exclusion Criteria

1. Emergent open heart surgery.
2. Patients scheduled to undergo mitral valve surgery, aortic, pulmonic or tricuspid valve replacements, and replacement or reconstruction of the aorta.
3. Patients who have undergone a previous open chest CABG procedure.
4. Previous history of atrial fibrillation or flutter.
5. Patient with clinical hypothyroidism or hyperthyroidism.
6. Prophylactic medication for the prevention of atrial fibrillation or current use of an antiarrhythmic medication. Patients who have been receiving beta-blockers and calcium channel blockers before screening may continue taking the medication.
7. First-degree or higher degrees of atrioventricular (AV) block (PR interval >210 msec)
8. An ejection fraction of less than 30%.
9. Clinically active congestive heart failure.
10. Serum creatinine > 2.0 mg/dL or currently receiving dialysis.
11. Clinically significant liver enzyme abnormalities (i.e., AST or ALT more than two times the upper limit of normal and/or bilirubin more than 50% above the upper limit of normal).
12. The patients will not be receiving concurrently an investigational product in another clinical trial or have received an investigational product in another clinical trial in the 30 days prior to enrollment.
13. Any other condition that, in the opinion of the clinical investigator, might compromise any aspect of the trial.