Inclusion Criteria:
1. At least 18 years old, or older if required by local law.
2. Subjects with symptomatic atrial fibrillation who have documented Persistent Atrial Fibrillation (PersAD) or Paroxysmal Atrial Fibrillation (PAF) with at least one documented symptomatic AF episode lasting at least 24 hours.
AND Undergone one failed endocardial atrial fibrillation ablation procedure OR undergone no more than two prior endocardial atrial fibrillation ablation procedures that were both limited to PV and/or PW ablation.
3. Willing and capable of providing informed consent.
4. Willing and capable of participating in all follow-up assessments and testing associated with this clinical investigation at an approved clinical investigational center.
5. Willing to receive a LUX-Dx insertable cardiac monitor (ICM) during the study or already has a LUX-Dx ICM that was inserted within 6 months prior to consent, and willing to comply with the LUX-Dx Latitude Clarity transmission instructions.
Exclusion Criteria:
1. Any of the following atrial conditions:
1. Left atrial anteroposterior (LA) diameter ≥ 6.5 cm, or if LA diameter is not available, non-indexed LA volume \>100 mL.
2. Current atrial myxoma.
3. Current left atrial thrombus.
4. Any PV abnormality, stenosis, or stenting. Common and middle PVs are admissible.
2. Any of the following cardiovascular conditions:
1. History of sustained ventricular tachycardia or any ventricular fibrillation.
2. Severe right ventricular dysfunction with documented echocardiography and/or hemodynamic data.
3. Atrial Fibrillation (AF) that is secondary to electrolyte imbalance, thyroid disease, alcohol, or other reversible/non-cardiac causes.
4. Presence of any of the following:
* Current or anticipated pacemaker, implantable cardioverter defibrillator, or cardiac resynchronization therapy device.
* Implantable loop recorder other than a LUX-Dx device
* Interatrial baffle, atrial septal defect or patent foramen ovale closure device or patch
* Left Atrial Appendage Closure or Occlusion Device
5. Presence of any of the following:
* Any cardiac valve prosthesis, ring, repair, or clip.
* Mitral valve stenosis: moderate or greater.
* Aortic stenosis: moderate or greater.
* Severe mitral regurgitation.
* Severe tricuspid regurgitation.
6. Hypertrophic or amyloid cardiomyopathy.
7. Any IVC filter, known inability to obtain vascular access, or other contraindication to femoral access.
8. Awaiting cardiac transplantation or other planned cardiac surgery within the next 12 months.
3. Any of the following conditions documented during eligibility assessment or Baseline Assessment, as applicable:
1. Heart failure associated with NYHA Class III or IV, as documented during eligibility assessment or Baseline Assessment.
2. Most recent documented LVEF \<40% within the previous 12 months.
3. Body Mass Index (BMI) \>45.0 kg/m², as documented during eligibility assessment or Baseline Assessment.
4. Known coagulopathy or bleeding disorder.
5. Contraindication to, or unwillingness to use, systemic anticoagulation or acceptable alternatives pre-, intra-, and post-procedure to achieve adequate anticoagulation.
6. Women who are confirmed to be pregnant or lactating at the time of the ablation procedure.
7. Severe lung disease, including but not limited to severe pulmonary hypertension, involving abnormal blood gases or requiring supplemental oxygen.
8. Active malignancy other than squamous cell carcinoma.
9. Clinically significant gastrointestinal problems involving the esophagus or stomach, including severe or erosive esophagitis, uncontrolled gastric reflux, gastroparesis, esophageal candidiasis, or active gastroduodenal ulceration.
10. Known active systemic infection.
11. Predicted life expectancy of less than one year per Investigator medical judgment.
12. Subjects who are currently enrolled in another investigational study or registry that would directly interfere with the current study, except when the subject is participating in a mandatory governmental registry or a purely observational registry with no associated treatments.
13. Required use of phosphodiesterase inhibitors within 24 hours of the ablation procedure.
14. Known allergic drug reaction to nitroglycerin, excluding hypotension.
15. Unwillingness to receive, or unable to tolerate, a subcutaneous, chronically inserted LUX-Dx ICM device.
16. Presence of an active spinal cord stimulator.
4. Any of the following congenital conditions:
1. Congenital heart disease with any clinically significant residual anatomic or conduction abnormality.
2. History of known congenital methemoglobinemia.
3. History of known G6PD deficiency.
5. Any of the following conditions in the medical history:
1. Solid organ or hematologic transplant, or currently being evaluated for a transplant.
2. Any prior history or current evidence of hemi-diaphragmatic paralysis or paresis.
3. Any documented history of Prinzmetal angina or severe non-revascularizable coronary disease.
4. Renal insufficiency if an estimated glomerular filtration rate (eGFR) is \<30 mL/min/1.73 m², or any history of renal dialysis or renal transplant.
5. Any other general health condition that, in the Investigator's medical opinion, would prevent participation in the study, interfere with assessment or therapy, significantly raise the risk of study participation, or modify outcome data or its interpretation.
6. Any of the following events within 90 days prior of the consent date:
1. Myocardial infarction, unstable angina, or coronary intervention.
2. Any cardiac surgery.
3. Heart failure hospitalization.
4. Pericarditis or symptomatic pericardial effusion.
5. Gastrointestinal bleeding.
6. Stroke, TIA, or intracranial bleeding.
7. Any active non-neurologic thrombus and/or thromboembolic event.
8. Carotid stenting or endarterectomy.
9. Uncontrolled diabetes mellitus or a recorded HbA1c \>8.0%.
