 Pulmonary vein isolation is an important treatment for patients with atrial fibrillation AF, particularly those in whom antiarrhythmic drugs are ineffective or cannot be tolerated. One method involves the use of radiofrequency energy and 3-D mapping system to produce a series of lesions small burn areas within the heart. Another method involves passing a balloon called a cryoballoon into the heart and freezing the parts of the heart muscle that the veins drain into. Both methods appear to be effective from known data. However, it is not known if use of either method alone or both together is the most effective. We aim to perform a prospective, randomized clinical trial comparing these three strategies. 