Study Abstract: Congestive heart failure (CHF) affects 4-5 million Americans, and its prevalence is predicted to increase over the next few decades. Thyroid hormone has unique actions which make it a novel and potentially useful agent for treatment of CHF. Due to possible adverse effects of thyroid hormone, there is interest in developing analogs with fewer undesirable side effects. DITPA has been shown to improve diastolic function in both animal models and a recently completed double-blind placebo controlled trial in 19 humans.