This clinical investigation is intended to demonstrate the safety and effectiveness of the TactiCath™ Contact Force Ablation Catheter, Sensor Enabled™ (TactiCath SE) for use in cardiac electrophysiological mapping and for the treatment of drug-refractory, recurrent symptomatic persistent atrial fibrillation (AF) when used in conjunction with a compatible radiofrequency (RF) generator and three-dimensional mapping system. This clinical investigation will be conducted under an investigational device exemption (IDE) and is intended to support market approval of the TactiCath SE ablation catheter for the treatment of drug refractory, symptomatic persistent atrial fibrillation in the United States.

Inclusion Criteria:

1. Patient must provide written informed consent prior to any clinical investigation related procedure.
2. Documented symptomatic persistent AF, which is defined as continuous AF sustained beyond 7-days and less than 1-year that is documented by (1) a physician's note and (2) a 24-hour Holter within 90-days prior to the procedure, showing continuous AF
3. Refractory or intolerant to at least one Class I-IV antiarrhythmic drug (AAD) as evidenced by recurrent symptomatic AF
4. Age 18 years or older
5. Able and willing to comply with all pre-, post-, and follow-up testing and requirements

Exclusion Criteria:

1. Continuous AF > 12 months (longstanding persistent AF)
2. Previous left atrial surgical or catheter ablation for atrial fibrillation or a previous procedure that required an incision in the left atrium with resulting scar
3. Any cardiac procedure (surgical or percutaneous) within 90-days prior to the initial procedure
4. CABG surgery within the 6-months (180-days) prior to the initial procedure
5. Valvular cardiac surgical/percutaneous procedure (i.e. ventriculotomy, valve repair or replacement and/or presence of a prosthetic or mechanical valve)
6. Any carotid stenting or endarterectomy
7. Documented or known left atrial thrombus on imaging
8. Left atrial diameter > 50 mm (parasternal long axis view or by CT)
9. Left ventricular ejection fraction < 40%
10. Unable to take anticoagulation medication due to contraindication or intolerance
11. History of blood clotting or bleeding abnormalities
12. Myocardial infarction (MI), acute coronary syndrome, percutaneous coronary intervention (PCI) within the 3-months (90-days) prior to the initial procedure
13. Documented thromboembolic event (including TIA) within the 12-months (365 days) prior to the initial procedure
14. Rheumatic heart disease
15. Uncontrolled heart failure or NYHA functional class III or IV
16. Severe mitral regurgitation (regurgitant volume ≥ 60 mL/beat, regurgitant fraction ≥ 50%, and/or effective regurgitant orifice area ≥ 0.40cm2)
17. Awaiting cardiac transplantation or other cardiac surgery within the 12-months (365 days) following the initial ablation procedure
18. Unstable angina at the time of the initial procedure
19. Acute illness or active systemic infection or sepsis
20. AF secondary to electrolyte imbalance, thyroid disease, acute alcohol intoxication, major surgical procedure in the preceding 3-months, or other reversible or non-cardiac cause
21. Diagnosed atrial myxoma
22. Presence of implanted implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D)
23. Significant pulmonary disease, (e.g., restrictive pulmonary disease, constrictive or chronic obstructive pulmonary disease) or any other disease or malfunction of the lungs or respiratory system that produces chronic symptoms
24. Significant congenital anomaly or other anatomic or comorbid medical problem that in the opinion of the investigator would preclude enrollment in this study or compliance with the follow-up requirements or impact the scientific soundness of the clinical trial results
25. Pregnant or nursing subjects and those who plan pregnancy during the clinical investigation follow-up period
26. Enrollment in an investigational study evaluating another device, biologic, or drug that may interfere with this clinical investigation at the time of the initial procedure or within 30 days prior to the initial procedure
27. Presence of any condition that precludes appropriate vascular access or manipulation of catheter
28. Life expectancy less than 12-months
29. Body mass index > 40 kg/m2
30. Known sensitivity to contrast media (if needed during the procedure) that cannot be controlled with pre-medication
31. Renal failure requiring dialysis
32. Vulnerable subject
33. History of atriotomy or ventriotomy
34. Implanted endocardial left atrial appendage occlusion device