The objective of this study is to establish the safety and effectiveness of a dual epicardial and endocardial ablation procedure for patients presenting with Persistent Atrial Fibrillation or Longstanding Persistent Atrial Fibrillation

The objective of this study is to establish the safety and effectiveness of a dual epicardial and endocardial ablation procedure for patients presenting with Persistent Atrial Fibrillation or Longstanding Persistent Atrial Fibrillation utilizing the AtriCure Bipolar System and AtriClip® PRO LAA Exclusion System in an endoscopic or open ablation procedure, followed by an endocardial mapping and ablation procedure utilizing commercially available RF based, irrigated, power controlled, ablation catheters for endocardial lesions. The endocardial procedure will be staged to occur after 90 days post epicardial surgical procedure.

Inclusion Criteria:

1. Symptomatic Persistent Atrial Fibrillation or Longstanding Persistent Atrial Fibrillation refractory to a minimum of one Class I or Class III AADs.

Exclusion Criteria:

1. AF >10 years.
2. Refractory hypertension, defined as systolic (>150 mm Hg) or diastolic (> 90 mm Hg) blood pressure that remains uncontrolled despite sustained therapy
3. History of pulmonary hypertension
4. Pulmonary vein stenosis in one or more of the pulmonary veins
5. EP catheter ablation procedure to treat atrial fibrillation within 3 months
6. Undergone prior cardiothoracic surgery, previous thorax trauma which resulted in a pneumothorax or hemothorax.
7. Sleep apnea, home oxygen therapy, moderate to severe COPD, (FEV1/FVC < 70% predicted) or patient is considered intolerant to single lung ventilation.
8. NYHA Class IV heart failure.
9. Uncorrected, reversible cause(s) of atrial fibrillation, or is currently being treated for arrhythmias other than atrial fibrillation (AF) or atrial flutter.
10. Documented history of previous catheter ablation with perforation, history of pericarditis, pericardial effusion, or tamponade.
11. Structural heart disease requiring surgical treatment (i.e. valve disease requiring repair or replacement within 12 months following surgical ablation procedure).
12. CAD requiring intervention (either surgical, i.e. CABG, or catheter).
13. Ejection fraction < 30%
14. Measured left atrial diameter > 5.5 cm
15. Stroke/cerebrovascular accident (CVA) within previous six months, carotid artery stenosis greater than 80%.
16. BMI is >40
17. Thrombus in the left atrium or the left atrial appendage, determined by echocardiography (either at baseline TTE (or equivalent diagnostic test) or intraoperative TEE).
18. Blood dyscrasia or clotting disorder (i.e. Idiopathic Thrombocytopenic Purpura [ITP] or Thrombotic Thrombocytopenic Purpura [TTP]).
19. Contraindication to anticoagulation that in the opinion of the investigator poses undue risk to the patient from participating in the endocardial EP procedure.
20. Documented thromboembolism within the previous six months prior to signing informed consent.
21. Has the following atrial myxoma, mural thrombus or mural tumor.
22. A condition or congenital anomaly which prevents required surgical or catheter access.
23. A co-morbid condition that, in the opinion of the investigator, poses undue risk of general anesthesia or port access cardiac surgery.
24. Currently abusing drugs or alcohol.
25. Currently or has participated in a clinical study in the last 3 months prior to signing informed consent.
26. A psychological disorder that could interfere with provision of informed consent, completion of tests, therapy, or follow-up.
27. A condition that, in the opinion of the investigator, may jeopardize the patient's well-being and/or the soundness of this clinical study.
28. Pre-existing esophageal condition that required (or requires) endoscopic therapy or surgical treatment.