After an initial safety study in 7 normal volunteers, a randomized double-blind 
comparison was made between 3,5-diiodothyropropionic acid (DITPA) and placebo in 
19 patients with moderately severe congestive failure. In heart failure patients 
receiving the drug for 4 weeks, cardiac index was increased (p = 0.04) and 
systemic vascular resistance index was decreased (p = 0.02). Systolic cardiac 
function was unchanged but isovolumetric relaxation time was decreased 
significantly, suggesting improvement in diastolic function. Total serum 
cholesterol (p = 0.005) and triglycerides (p = 0.01) also were decreased 
significantly. DITPA could represent a useful new agent for treatment of 
congestive heart failure.