Rationale: Despite new therapeutic interventions, the prognosis of heart failure patients remains grim with 5-year survival rates usually less than 50%. In most recent, large CHF trials, AF has been reported to be independently associated with increased mortality. Non-randomized observations also suggest that patients with AF in the setting of CHF have a greater tendency to revert to sinus rhythm during amiodarone therapy or with newer class III antiarrhythmic agents and that those who maintain a normal rhythm have a better prognosis. There is a need to determine whether a treatment strategy that attempts to maintain sinus rhythm will have a beneficial impact on cardiovascular mortality in CHF patients. This hypothesis has never been tested in a prospective, controlled, adequately-powered randomized trial.