This study is a prospective, randomized controlled study to compare overall clinical outcomes between High Power Short Duration (HPSD) and standard radiofrequency (RF) ablation settings for Atrial Fibrillation (AF) ablation in the treatment of subjects with paroxysmal or persistent Atrial Fibrillation.

Pulmonary vein isolation using radiofrequency (RF) ablation is a widely used treatment strategy for atrial fibrillation. Peri-procedural complications rates are estimated at between 1.5 - 6% with the two most feared complications being stroke and atrial-esophageal fistula. The risk of these complications increases with (1) longer left atrial dwell times with greater potential for clot formation and (2) esophageal heating during delivery of radiofrequency energy. 'High-power short-duration' (HPSD) is an increasingly utilized strategy to decrease procedure duration and minimize the risk of these complications. Potential mechanisms for benefit include: (1) shorter left atrial dwell times due to more efficient lesion delivery (2) rapid, but more controlled, resistive tissue heating, which avoids deeper, passive conductive heating that can reach the esophagus and cause injury. Moreover, HPSD may improve lesion efficacy and durability due to less recover of excitability after ablation. Despite being widely used and several retrospective studies, there have been no prospective randomized trials comparing outcomes between HPSD and standard RF ablation settings. Moreover, the investigators are interested to see if a shorter procedure (less time in the left atrium) is associated with a lower rate of silent cerebral infarctions (which are occasionally seen on MRI brain post RF ablation - their clinical significance is unclear).

Inclusion Criteria:

1. Male or female ≥18 years of age at their pre-operative visit.
2. Patient is scheduled to have their first AF ablation
3. Paroxysmal or persistent AF
4. Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study.

Exclusion Criteria:

1. Prior AF ablation
2. Stroke or transient ischemic attack (TIA) within the previous 6 months
3. Known esophageal ulcer or gastrointestinal (GI) bleed within prior 6 months
4. Intent to perform adjunctive left atrial ablation, including posterior wall isolation, left atrial appendage isolation, mitral or other linear lesions.
5. Prior rheumatic heart disease or significant mitral stenosis
6. Mechanical mitral valve replacement
7. Long lasting persistent AF > 1 year
8. Severe left ventricular systolic dysfunction, with LV ejection fraction LVEF<35%
9. Prior left atrial appendage (LAA) occlusion device
10. Prior septal occlusion device
11. Pregnancy
12. Pacemaker, defibrillator or any contraindication to MRI

We are open to collaboration but do not plan to give our data to others.