Cryoballon Versus Radiofrequency Ablation for Persistent Atrial Fibrillation

Inclusion Criteria: 1. Candidates for AF ablation based on AF that is symptomatic and refractory to at least one antiarrhythmic medication. 2. Patients presenting with Persistent AF with AF duration \< 2 years scheduled to undergo a PVAI procedure 3. Age range of 18 - 85 years 4. Patients with already implanted devices with AF detection capabilities (for clinical indications): ILR implanted in the same hospital stay or within 6 months before the ablation or patients with an dual chamber PM, ICD or CRTD and an existing functional atrial lead. 5. Patients must be able and willing to provide written informed consent to participate in the clinical trial. Exclusion Criteria: * Congenital heart disease, age younger than 18 years, significant valve disease, LA size \>55 mm, and severe heart failure (ejection fraction \< 30% and/or New York Heart Association class IV). * Presence of a mechanical prosthetic valve. * Secondary causes of atrial fibrillation * Documented intra-atrial thrombus or another abnormality which precludes catheter introduction. * Social factors that would preclude follow up or make compliance difficult.- * Patients who are or may potentially be pregnant Previous left atrial catheter ablation or MAZE procedure.