[THE SYNDROME «LOW TRIIODOTHYRONINE» AND A COURSE A HEART FAILURE]

Area of Science:

• Cardiology
• Endocrinology
• Internal Medicine

Background:

• Heart failure (HF) is a complex condition often associated with other comorbidities.
• Post-infarction cardiosclerosis, a consequence of myocardial infarction, can lead to or exacerbate HF.
• Low triiodothyronine syndrome (LT3S) is observed in various critical illnesses, but its specific impact on HF post-myocardial infarction requires further investigation.

Purpose of the Study:

• To investigate the effect of low triiodothyronine syndrome (LT3S) on the clinical course of heart failure (HF) in patients with post-infarction cardiosclerosis.
• To establish diagnostic criteria for LT3S in this patient population.
• To identify predictors of re-hospitalization in HF patients with LT3S.

Main Methods:

• A biennial study involving 157 patients hospitalized with HF secondary to coronary heart disease and myocardial infarction.
• Standardized assessment including hemodynamic parameters, clinical and biochemical blood tests, and thyroid hormone levels (TSH, free T3, free T4, reverse T3).
• Statistical analysis to determine the diagnostic threshold for LT3S and develop a regression model for re-hospitalization risk.

Main Results:

• A serum free T3 (fT3) level ≤2.07 pmol/l was identified as a diagnostic marker for LT3S in HF patients with post-infarction cardiosclerosis.
• The prevalence of LT3S in hospitalized HF patients was 17.8%.
• Patients with LT3S were younger, exhibited larger left ventricular dimensions, reduced ejection fraction, and a significantly higher relative risk of re-hospitalization within 2 years (2.224 [1.363-3.630]).
• A regression model for HF re-hospitalization included weight, thyroxine and triiodothyronine concentrations, non-toxic goiter, height, total cholesterol, LDL cholesterol, and blood granulocytes. Risk increased with a model score ≥1.321 (sensitivity 93.78%, specificity 40.45%).

Conclusions:

• LT3S is a significant finding in HF patients with post-infarction cardiosclerosis, associated with distinct clinical characteristics.
• Serum fT3 levels serve as a reliable diagnostic indicator for LT3S in this cohort.
• LT3S is a strong predictor of HF decompensation and re-hospitalization, highlighting the importance of thyroid hormone assessment in managing these patients.