Study hypothesis: Comparing the effect of digoxin and ivabradine in chronic heart failure patients with a left ventricular ejection of 35% or lower and sinus rhythm with heart rate 70 beats per minute or higher, and who are taking maximal dose of a beta blocker if tolerated.

Selected patients have chronic heart failure with left ventricular systolic dysfunction and sinus rhythm. They take optimal medical therapy.

1. Inclusion Criteria:

   • Left ventricular ejection fraction of 35% or lower (Ischaemic or non-ischaemic etiology)
   • Sinus rhythm with heart rate of 70 beats per minute or higher
   • Symptomatic heart failure with functional capacity of New York Heart Association class II, III, IV

2. Exclusion Criteria:

   • Chronic renal failure with glomerular filtration rate <30 ml/min
   • Atrial fibrillation
   • Pace maker rhythm
   • Advanced stage chronic obstructive lung disease
   • Comorbidity with expected survival below 1 year