Thyroid hormone is a critical determinant of myocardial performance in patients with heart failure: potential therapeutic implications.

Objective: Previous experimental studies have provided evidence showing that changes in thyroid hormone signaling correspond to alterations in myocardial function in animal models of heart failure. The present study further explores whether thyroid hormone alterations are correlated with the functional status of the myocardium in patients with heart failure. Methods: In this study, 37 patients with mean ejection fraction (EF%) of 26.2 (8.2) were included. Myocardial performance was assessed by echocardiography and cardiopulmonary exercise testing. Total tri-iodothyronine (T 3 ), thyroxine, and TSH levels were measured in plasma. Results: Total T 3 was strongly correlated with VO 2max (r=0.78, P=2×10 -8 ). Furthermore, multivariate analysis revealed that total T 3 was an independent predictor of VO 2max (P= 0.000 005). Aweaker but significant correlation was also found between total T 3 and EF% (r=0.56, P=0.0004), systolic (r=0.43, P=0.009) and diastolic (r=0.46, P=0.004) blood pressure. Conclusions: changes in thyroid hormone were closely correlated to myocardial functional status in patients with heart failure. These data probably indicate a possible role of thyroid hormone in the pathophysiology of heart failure and confirm previous experimental reports.