Left ventricular assist devices provide chronic pressure and volume unloading of the dilated left ventricle in patients with end-stage heart failure. This is associated with reverse structural remodeling (normalization of the passive pressure-volume relationship), reverse molecular remodeling (increased expression of several genes involved in calcium metabolism that are down-regulated in heart failure), improved baseline contractility, and improved contractile response to increased heart rate and to beta-agonist stimulation. These findings indicate the profound degree of recovery of myocardial properties in hearts previously considered to have invincible end-stage heart failure.