Pingitore A et al. (2008) Acute effects of triiodothyronine replacement therapy in patients with chronic heart failure and low-T3 syndrome: a randomized, placebo-controlled study. J Clin Endocrinol Metab [doi:10.1210/jc.2007-2210]

A syndrome of low endogenous T3 has been reported in patients with dilated cardiomyopathy; development of low-T3 syndrome predicts a poor outcome in these patients. The pathophysiological role of decreased T3 levels and the usefulness of synthetic thyroid hormone (liothyronine) administration in patients with heart failure are not yet fully known. Pingitore and colleagues, therefore, analyzed the effect of liothyronine treatment on the clinical status, left ventricular function and neuroendocrine profile of patients with dilated cardiomyopathy. Twenty clinically stable patients (age range 64–77 years) with ischemic or nonischemic dilated cardiomyopathy were randomly allocated to 3 days of treatment with intravenous liothyronine or placebo infusions.

Liothyronine was well tolerated. In liothyronine-treated patients, blood levels of norepinephrine, N-terminal brain natriuretic propeptide and aldosterone decreased substantially compared with baseline values. These changes were not observed in placebo-treated patients. Liothyronine treatment also increased end-diastolic left ventricular volume and stroke volume, whereas it did not alter cardiac workload.

The authors conclude that short-term administration of liothyronine reduces activation of the neuroendocrine system and improves left ventricular performance in patients with dilated cardiomyopathy and low-T3 syndrome. They suggest that further trials should be performed to determine whether the observed effects will be sustained during chronic administration of liothyronine.