Low Voltage-Directed Catheter Ablation for Atrial Fibrillation

Patients that meet both inclusion and exclusion criteria will be randomized by the study
clinical center. Patients will be randomized 1:1:1 into one of the following arms:

- PVI with additional total left atrial low voltage-directed ablation.

- PVI with posterior wall low voltage quantification and isolation

- PVI alone without low voltage quantification.

All patients will receive the best conventional medical therapy and anticoagulation use based
upon HRS consensus recommendations taking into account their baseline risk factors for
stroke. The need for interruption of anticoagulation and antiarrhythmic drug therapy for the
procedure will be determined by the operator and their center guidelines.

The trial requires continuous monitoring for atrial arrhythmias. Investigators will mandate
the use of implantable loop recorders (ILR). The device will be under sterile conditions at
the manufacture's recommended site on the precordium for arrhythmia monitoring. Implantation
will occur between 1 month prior and 3 months post ablation since there will be a 3 month
post ablation blanking period. If a dual chamber device is already present, implantation will
not be required.

One year follow-up is planned. Post procedure care is per standard of care with follow-up at
1 month, 3 months, 6 months, 9 months and 12 months. ECG at every follow-up is performed.
Download of arrhythmia data will occur at each of these visits as well. Investigators will
use the typical post ablation blanking period for recurrence of atrial fibrillation of 3
months. Antiarrhythmic medications can be used during the typical "blanking period" of 3
months post procedure. But per protocol are stopped at 3 months post procedure (2 months post
procedure in case of amiodarone).

Investigators will compare time freedom from first arrhythmia event, defined as a sustained
episode of atrial fibrillation or atrial tachycardia. Secondary endpoints will be compared as
well (see secondary end point defined). Re-initiation of an antiarrhythmic drug after 3
months will be considered a failure of primary endpoint of arrhythmia free survival. However,
Anti-arrhythmic medication use after the blanking period for ventricular arrhythmias will not
be included as an event. Anticoagulation is continued and monitored based on previous
guidelines with use stratified by baseline stroke risk. A recording (CD) of the mapping
during the procedure is to be obtained and retained for possible future analysis.

Inclusion Criteria:

Subjects must meet all of the following criteria:

1. Non-Paroxysmal Atrial Fibrillation.

2. Failed or intolerable to at least 1 one antiarrhythmic drug (AAD).

3. 18-85 year of age at time of consent.

4. Able and willing to comply with all protocol visit requirements.

5. Signed Patient Informed Consent (ICF).

Exclusion Criteria:

Subjects will be excluded if any of the follow criteria are present:

1. History of prior left-sided catheter or surgical ablation for AF or atypical atrial
flutter, including MAZE or mini MAZE.

- Prior ablation for typical atrial flutter or left-sided ablation for WPW, AV node
reentry tachycardia or focal ectopic atrial tachycardia may be included.

2. Uncontrolled heart Failure or NYHA Class IIIb or IV heart failure.

3. Ejection Fraction < 0.20.

4. Active ventricular tachycardia requiring treatment with catheter ablation or
anti-arrhythmic drug within the last 6 months.

5. Left atrial size > 60 mm diameter on echocardiogram.

6. "Long standing" persistent AF defined as > or = 1 year of continuous atrial
fibrillation at the time of enrollment.

7. Severe pulmonary hypertension (PAP > 70 mmHg)

8. AF secondary to electrolyte imbalance, thyroid disease or reversible non- cardiac
cause.

9. Poor candidate for general anesthesia.

10. Anticipated survival < 1 year.

11. MI or CABG within 3 months.

12. Left atrial thrombus in pre-procedure imaging within 4 weeks of the ablation
procedure.

13. Any documented thromboembolic event within 6 months of the ablation procedure.

14. Contraindication to anticoagulation.

15. Inability to have implantable monitoring device for atrial fibrillation burden with no
pre-existing cardiac device that can monitor atrial arrhythmias.

16. Significant congenital anomaly or medical condition that may affect the integrity of
study data.

17. Women who are pregnant - pregnancy test required if pre-menopausal or non-sterile.

18. Active enrollment in another investigational study involving a drug or device.

19. Inability to undergo complete voltage mapping in normal sinus rhythm - see
intraprocedural protocol.