Effects of triiodothyronine replacement therapy in patients with chronic stable heart failure and low‐triiodothyronine syndrome: a randomized, double‐blind, placebo‐controlled study

OBJECTIVES: The present study assessed the changes in functional, biochemical, and echocardiographic measures following long‐term liothyronine therapy in heart failure (HF) patients with low‐triiodothyronine (T3) syndrome (LT3S). METHODS: In the present placebo‐controlled, double‐blind study, adult patients with clinically stable New York Heart Association functional class I–III systolic HF and LT3S receiving standard HF therapy were randomly assigned 1:1 to receive oral liothyronine or placebo for 6 weeks. Low‐T3 syndrome was defined as a serum free T3 of less than the lower limit of normal (<2.4 pg/mL) with normal thyroid‐stimulating hormone (thyrotropin) and free thyroxin values. RESULTS: Fifty patients, including 39 (78%) men with a mean ± standard deviation age of 60 ± 15 years were included. The 6‐min walk distance increased in the liothyronine group by 93 ± 16 m and in the placebo group by 67 ± 28 m, resulting in a treatment effect of 26 m (P = 0.003). A higher decrease of high‐sensitivity C‐reactive protein level was seen in the liothyronine group than in the placebo group (P = 0.009). Liothyronine markedly decreased serum N‐terminal pro‐brain natriuretic peptide level compared with the placebo (P = 0.01). A significant increase was also seen in the left ventricular ejection fraction by liothyronine as compared with the placebo (<0.001). CONCLUSION: Triiodothyronine replacement by chronic liothyronine therapy seems to safely benefit stable HF patients with LT3S receiving optimal HF medications.