Effect of Ivabradine in Stage D HF/Cardiogenic Shock Patients on Dobutamine

This is a randomized, double blind, single center trial to study of the effects of Ivabradine vs. Placebo on patients hospitalized for Stage D heart failure (HF)/ and cardiogenic shock (CS) who will require continuous infusion of Dobutamine and have developed sinus tachycardia (ST) (heart rate \>100 beats/min). The aim of the study will be to assess the potential of Ivabradine to slow ST and improve hemodynamics in patients with stage D HF/CS on Dobutamine treatment.