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 affects of thyroid hormone, there is interest in developing analogs with fewer undesirable side effects. 3,5- diiodothyropropionic acid (DITPA) has been shown to improve diastolic function in both animal models and a recently completed double-blind placebo controlled trial in 19 humans.