Ivabradine is a selective inhibitor of the If pacemaker current, and as such decreases heart rate without inducing any negative inotropic effects. Experimental and clinical evidence suggests that the beneficial effects of -blockers in heart failure are mediated by a reduction in heart rate. Long-term heart rate reduction with ivabradine in a rat model of heart failure elicited an improvement in left ventricular function and a positive effect on cardiac remodeling, leading to a decrease in collagen density and an increase in capillary density. In addition, recent evidence indicates that the If current may be reexpressed in animal and human ventricular myocytes from failing hearts and may have an arrhythmogenic role. If inhibition would thus exert an antiarrhythmic effect in heart failure, but this hypothesis remains to be proven in the clinical setting...