This is a prospective, randomized study designed to evaluate if CRT device optimization, guided by electrocardiography, improves echocardiographic and clinical outcomes among HF patients with a CRT device implanted for standard indications. All patients will have measurement of electrocardiograms at a range of device settings. Patients will be randomized in a 1:1 ratio to either the active comparator arm (standard CRT programming), or the experimental arm (CRT device programmed by the information obtained by ECGs). Standard CRT programming used in this study is simultaneous biventricular (BiV) pacing with a fixed atrioventricular delay. At 6 months, control patients who were initially randomized to standard programming will have programming changed based on the ECG optimization information. Patients will be blinded to randomization. Change of LV size and function will be performed prior to randomization, and again \~6 and \~12 months following CRT implant in both subgroups.
