The overall goal is to determine the safety, feasibility, and preliminary efficacy of administering oral LT3 therapy in the study population of participants with Heart Failure with reduced ejection fraction (HFrEF). The study will consist of two treatment periods - each treatment period will be approximately 8 weeks in duration, with weekly titration of study drug for 4 weeks, followed by a maintenance dose for 4 weeks, then 2-week washout before crossing over to the other arm (placebo or drug). LT3 will be titrated to T3 levels.
