Congestive heart failure (CHF) and atrial fibrillation (AF) are two important and growing problems in medicine and cardiology. Both conditions often co-exist and complicate each other's management. Two therapeutic strategies are available for patients with AF and CHF: the first aims at restoring and maintaining sinus rhythm, whereas, the second focuses exclusively on optimizing ventricular rate. The primary objective of the Atrial Fibrillation and Congestive Heart Failure (AF-CHF) trial is to compare these two widely-used treatment strategies with respect to cardiovascular mortality.