The Effect of Beta-Blockers on a Course of Chronic Heart Failure in Patients With a Nontoxic Goiter

The major cause of mortality in many countries is cardiovascular pathology. Heart failure (HF) is the final stage of the cardio-vascular continuum. Recent years, interest in the study of comorbidity in HF has increased significantly. This is due to the fact that the concomitant pathology not only affects the severity of the HF course, but also can determine the variability of the response to prescribed treatment. Non-toxic goiter (NTG) is one of the most common thyroid pathology in our country. At NTG in some patients changes in thyroid function are detected. Subclinical and clinical hypothyroidism are often observed. Thyrotoxicosis may develop over the years due to the "autonomization" of thyroid nodules. Earlier, we reported that patients with NTG have a high incidence of the low T3 syndrome (LT3S) in HF. β-blockers (β-AB) reduce mortality (up to 30%) in HF. In addition, this group of drugs did not show a significant effect on survival in decompensated patients. It is also known that β-AB lead to blockade of deiodinases, which leads to a decrease in T4 to T3 conversion, that is why they are prescribed to patients with hyperthyroidism. It can be assumed that the use of β-AB in HF in patients with NTG requires more detailed study. Objective: to study the effect of the use of β-blockers (β-AB) in patients with NTG on the course of HF. Object and research methods. 381 patients with HF on a background of post-infarction cardiosclerosis were included. In 218 (57.2 %) patients were diagnosed with NTG. Levels of TSG, T3f and T4f were evaluated. Echocardioscopy and ultrasound examination of the thyroid gland were performed. The course of HF was studied for 2 years. Results. Patients with HF without NTG who received bisoprolol at dose over 5 mg had a significant reduction in the risk of re-hospitalization (RH) (odds ratio (OR) = 0.174 (0.057-0.530), p = 0.002) and combined endpoint (CE) (OR = 0.403 (0.180-0.905), p = 0.025), comparing to patients who received β-AB at a dose lower or equal 5 mg as a result of intolerance or low compliance. It was not possible to detect a decrease in the risk of a non-sensitive course of HF with increasing dose of β-AB in the group of patients with NTG. Patients with NTG have a higher incidence of low T3 syndrome (LT3S), compared to patients without NTG (39.4 % vs. 9.8 %, respectively, at p = 0.0001). Prescribing β-AB in patients with NTG but without LT3S leads to a decrease in the risk of RH due to HF decompensation (OR = 0.399 (0.173-0.925), p = 0.029) and CE (OR = 0.419 (0.188-0.935), p = 0.031). Prescription of β-AB at a dose over 5 mg in patients with NTG without LT3S leads to a further reduction in the risk of RH (OR = 0.123 (0.035-0.431), p = 0.0001) and CE (OR = 0.224 (0.086-0.587), p = 0.001). Conclusions. The use of β-AB in patients with NTG has no dose-dependent effect on the course of HF. A probable cause of this is the high incidence of LT3S among patients in this population. The use of β-AB in patients with NTG without LT3S leads to a significant reduction in RH frequency and the risk of CE developing within 2 years.