- 1. AF without indication for mitral valve surgery 2. AF is paroxysmal 3. Evidence of left atrial thrombus by intra-operative TEE 4. Evidence of active infection 5. Mental impairment or other conditions that may not allow subject to understand the nature, significance, and scope of study 6. Surgical management of hypertrophic obstructive cardiomyopathy 7. Previous catheter ablation for AF 8. Life expectancy of less than one year 9. Absolute contraindications for anticoagulation therapy 10. Enrollment in concomitant drug or device trials 11. Uncontrolled hypo- or hyperthyroidism 12. FEV1 < 30% of predicted value and/or need for home oxygen therapy 13. Women who are pregnant as evidenced by positive pregnancy test 14. Women of childbearing age who do not agree to be on adequate birth control throughout the period of the trial.