Introduction: Progression of heart failure (HF) leads to hormonal changes, including low triiodothyronine syndrome (LT3S). b-blockers (b-AB) reduce the activity of deiodinases, which leads to a decrease in triiodothyronine (T3) levels. Presumably the use of b-ABs in patients with LT3S may influence the course of the disease.
The aim is to study the effect of b-ABs in patients with LT3S on the course of HF.
Materials and methods: 354 patients with HF on a background of post-infarction cardiosclerosis were included in the 2-yeared follow-up study. LT3S was diagnosed at 89 (25.1%) patients. The levels of thyroid-stimulating hormone, free T3f and T4f, and reversible T3 were determined. The echocardioscopy was performed.
Results: Patients with HF in combination with LT3S have a heavier functional class by NYHA, greater dilatation of the left heart cavities, less myocardial contractility, a higher frequency of atrial fibrillation and re-hospitalization. The use of b-ABs in patients with HF without LT3S leads to a likely decrease in hospitalization frequency, while in patients with LT3S it has an opposite effect. The frequency of rehospitalization increases with an excess of b-ABs dose > 5 mg (equivalent to bisoprolol). At these patients a decrease in serum T3 level and negative dynamics of parameters of intracardiac hemodynamics are observed.
Conclusions: The use of b-ABs in patients with LT3S leads to an increase in re-hospitalization at a dose over 5.0 mg (equivalent to bisoprolol). In these patients there is a decrease in serum T3, an increase in T4 level; and the ejection fraction decrease; and heart cavities size increase.
Key words: low triiodothyronine syndrome, b-blockers, thyroid-stimulating hormone, ROC curve, risk, ventricular dilatation, reversible triiodothyronine, heart failure.