Background: This study was conducted to compare rate- and rhythm-control therapy in patients with persistent atrial fibrillation (AF) and mild to moderate chronic heart failure (CHF). Rate control is not inferior to rhythm control in preventing mortality and morbidity in patients with AF. In CHF, this issue is still unsettled. Methods: In this predefined analysis of the RACE study, a total of 261 patients were in New York Heart Association (NYHA) classes II and III at baseline. These patients were analyzed. The primary end point was a composite of cardiovascular mortality, hospitalization for CHF, thromboembolic complications, bleeding, pacemaker implantation, and life-threatening drug side effects. Furthermore, quality of life was compared. Results: After 2.3 ± 0.6 years, the primary end point occurred in 29 (22.3%) of the 130 rate-control patients and in 32 (24.4%) of the 131 rhythm-control patients. More cardiovascular deaths, hospitalization for CHF, and bleeding occurred under rate control. Thromboembolic complications, drug side effects, and pacemaker implantation were more frequent under rhythm control. Quality of life did not differ between strategies. In patients successfully treated with rhythm control, the prevalence of end points was not different from those who were in AF at study end. However, the type of end point was different: mortality, bleeding, hospitalization for heart failure, and pacemaker implantation occurred less frequently. Conclusions: In patients with mild to moderate CHF, rate control is not inferior to rhythm control. However, if sinus rhythm can be maintained, outcome may be improved. A prospective randomized trial is necessary to confirm these results. © 2005, Elsevier Inc. All rights reserved.