Objectives: Low-triiodothyronine syndrome (LT3S) is a condition characterized by decreased total serum T3 and free T3 (fT3) with normal levels of thyroxine (fT4) and thyrotropin (TSH). Experimental studies have shown that altered thyroid hormones (THs) metabolism modifies cardiovascular homeostasis.
The aim of the study was to evaluate prospectively the reversibility and pathophysiological implications of sick euthyroid syndrome in patients with moderate-to-severe chronic heart failure.
This study should demonstrate the role of short-term acute dobutamine heart failure (HF) treatment in improving thyroid hormone, neuroendocrine profile, and ventricular performance in patients with worsening HF and LT3S.
Methods: During hospitalization for worsening heart failure, fT3, fT4, and TSH levels; brain natriuretic peptide; and echocardiographic and right hemodynamic parameters were recorded on admission, after HF treatment and after dobutamine infusion in patients with LT3S.
Results: We evaluated 60 patients hospitalized for severe acute decompensated HF. Fourteen patients (23%) of the population presented an LT3S. Dobutamine infusion in LT3S patient group evoked a statistically significant cardiac index increase, pulmonary capillary arterial wedge pressure, and right atrial pressure decrease with left ventricle diastolic dysfunction recovery; the hemodynamic and clinical improvement were associated with brain natriuretic peptide reduction and increased fT3 levels. Free T3 levels increased in all of them and normalized in 6 patients (42%). Free T4 and TSH values remained unchanged.
Conclusions: These data suggest that LT3S in patients with acute decompensated HF can be useful in assessing the status and clinical course for this disease. These preliminary results indicate that LT3S reversibility by dobutamine is associated with short-term hemodynamic and neurohormonal improvement in patients with persistent severe heart failure.