The purpose of this research study is to determine how safe and effective the investigational device is when compared to what is currently FDA approved. The device under study is the Blazer Open-Irrigated Catheter. The catheter is used to treat patients who have paroxysmal atrial fibrillation, and have major inclusion criteria of drug refractory, older than 18 years of age, and has at least one documented case of parox. atrial fibrillation. Patients who do qualify for this study will be randomized between this investigational catheter and the control device. Control device is the fda approved Thermocool catheters. Main intervention of the study is ablation via one of these catheters which is dependent on randomization. Also, there is a sub-study in this protocol. Participants will be randomized for a second time to determine if they will be enrolled into a pulmonary vein imaging study. The purpose of this sub study is to assess the potential of pulmonary vein narrowing when performing radio frequency ablations (RFA's) using open irrigated catheters. The study is looking to enroll 100 subjects into this sub study. The procedures invovlved with this sub-study is a baseline CT/MRI image of the pulmonary veins prior to ablation and another CT/MRI image of the veins post ablation at the 3-6 month visit.

You may be eligible for this study if you meet the following criteria:

• Conditions: Atrial Fibrillation
• Age: 1 years - 99 years
• Gender: All