The objective of this prospective multicenter randomized study is to establish the effectiveness of treatment of persistent atrial fibrillation by encircling the pulmonary veins with radiofrequency (RF) ablation and creating additional lines of block with the aid of the NAVISTAR® THERMOCOOL® catheter in conjunction with the CARTO™ EP Navigation System. Effectiveness will be determined by comparing the chronic success of ablation therapy versus antiarrhythmic drug therapy, defined as the absence of persistent tachyarrhythmias during the first 24 months after a run-in phase of 2 months.