Atrial Fibrillation Stratification Based on the Arrhythmia Perpetuation Mechanisms

Inclusion Criteria: * Patients with paroxysmal AF symptomatic and refractory to at least one antiarrhythmic medication arriving in atrial fibrillation to the AF clinic. * Patients with paroxysmal AF undergoing AF ablation in whom AF was induced at the EP laboratory. * Patients with persistent AF or long-term persistent AF attending the AF clinic. * Patients must be able and willing to provide written informed consent to participate in the study. * Prior anticoagulation for\> 4 weeks or transesophageal echocardiogram excluding intracardiac thrombi. Exclusion Criteria: Inclusion Criteria: * Patients with paroxysmal AF symptomatic and refractory to at least one antiarrhythmic medication arriving in atrial fibrillation to the AF clinic. * Patients with paroxysmal AF undergoing AF ablation in whom AF was induced at the EP laboratory. * Patients with persistent AF or long-term persistent AF attending the AF clinic. * Patients must be able and willing to provide written informed consent to participate in the study. * Prior anticoagulation for\> 4 weeks or transesophageal echocardiogram excluding intracardiac thrombi. Exclusion Criteria: * Patients with inadequate anticoagulation levels, left atrial thrombus, tumor, or another abnormality which precludes catheter introduction on TEE prior to the procedure. * Patients with moderate-to-severe mitral regurgitation. * Patients with contraindications to systemic anticoagulation with heparin or coumadin. * Patients who are or may potentially be pregnant. * Current enrollment in another investigational drug or device study. * Pacemaker or Implantable Cardioverter Defibrillator.