This study aims to determine whether giving triiodothyronine (T3), a thyroid hormone, is safe and helps improve symptoms and signs of heart failure.
Participants who are enrolled to receive the study drug will be admitted to the General Clinical Research Center (GCRC) for 5 days for oral thyroid hormone treatment and monitoring. They will have 4 additional follow-up visits over the next year. Participants who are not enrolled to receive the study drug will not be admitted but will have similar follow-up visits in the outpatient setting.
If this study finds that patients have improved heart function after thyroid hormone treatment without unacceptable side effects, it could lead to a new treatment for patients with heart failure.