Background: Atrial fibrillation is common in chronic heart failure. Long-term restoration of sinus rhythm is generally unsuccessful. It may be speculated tha t higher heart rates are unfavorable, since this may lead to tachycardiomyopathy , but there are no data which have examined this. Methods and results: Seventy- seven patients with atrial fibrillation and advanced chronic heart failure, age 70±7 years, left-ventricular ejection fraction 0.23±0.08, 61%with ischemic e tiology were included. Patients were dichotomized according to the median heart rate(80 bpm) at inclusion(39 patients with “low”heart rate and 38 patients wit h “high”heart rate). At baseline, both patient groups were remarkably comparab le. After a mean follow-up of 3.3±0.9 years, mortality was comparable(62%vers us 55%, p=non-significant). An independent relation was found between lower he art rate and survival, in addition to absence of hypertension, digoxin use, and higher N-ANP, dopamine, and renin levels. Conclusion: In the present analysis, patients with atrial fibrillation and advanced chronic heart failure with higher heart rates are comparable to those with lower heart rates. Not higher heart ra tes at baseline but, on the contrary, lower heart rates seem associated with a w orse outcome. Background: Atrial fibrillation is common in chronic heart failure. Long-term restoration of sinus rhythm is generally unsuccessful. It may be speculated tha t higher heart rates are unfavorable, since this may lead to tachycardiomyopathy, but there are no data which which involve this . Methods and results: Seventy-seven patients with atrial fibrillation and advanced chronic heart failure, age 70 ± 7 years, left-ventricular ejection fraction 0.23 ± 0.08, 61% with ischemic etiology were included. Patients were dichotomized according to the median heart At baseline, both patient groups were remarkably comparab le. After a mean follow-up of 3.3 ± 0.9 years (39 patients with “low” heart rate and 38 patients wit h “high” heart rate) , was was found (62% versus 55%, p = non-significant). An independent relation was found between lower he art rate and survival, in addition to absence of hypertension, digoxin use, and higher N-ANP, dopamine, and renin leve ls. Conclusion: In the present analysis, patients with atrial fibrillation and advanced chronic heart failure with higher heart rates are comparable to those with lower heart rates. aw orse outcome.