The cardiovascular system is one of the main targets of thyroid hormone action, and triiodothyronine deficiency has crucial consequences on cardiac structure and function. Patients with overt or subclinical hypothyroidism should be treated with levothyroxine to improve their cardiovascular function and the potential risk of heart failure. Even patients with thyroid hormone deficiency and heart failure should receive replacement doses of levothyroxine to improve their prognosis and worsening of the cardiovascular function. An innovative therapeutic multifactorial approach could improve the progression of heart failure. There is a potential beneficial effect of thyroid hormones and their analogs in patients with heart failure.