Selenium deficiency and the dynamics of changes of thyroid profile in patients with acute myocardial infarction and chronic heart failure

Background: Selenium (Se) is incorporated in 25 enzymes, for example, glutathione peroxidase (activatedb by oxidative stress) and deiodinases (converting thyroid hormones). Oxidative stress present in heart failure (HF) and myocardial infarction (MI) might cause Se deficiency and decreased thyroxine to triiodothyronine conversion. Aims: We sought to evaluate Se levels in Polish patients with MI, HF, and healthy volunteers in relation to thyroid hormone levels. Methods: The study group consisted of 143 participants: 54 patients with MI, 59 patients with decompensated HF, and 30 healthy matched volunteers. The patients underwent echocardiography and laboratory tests on admission and 5 months later. Results: Se levels were lower in patients with MI and HF than in controls (median [interquartile range, IQR], 65.9 [55.2–76.1] μg/l and 59.7 [47.7–70.7] μg/l vs 93.2 [84.2–99.1] μg/l, respectively; P < 0.001). The Se deficiency was very common in patients with MI and HF, while it was rare in controls (70.37% and 74.58% vs 10%, respectively; P < 0.001). Patients with MI and HF presented lower free triiodothyronine (FT3) levels and lower FT3 to free thyroxine (FT4) ratio in comparison with controls (median [IQR], 3.90 [3.60–4.38] pmol/l and 4.25 [3.57–4.60] pmol/l vs 4.92 [4.50–5.27] pmol/l; P < 0.001; and 0.25 [0.23–0.29] and 0.25 [0.21–0.28] vs 0.32 [0.29–0.37]; P < 0.001, respectively). There was a weak to moderate correlation between Se level, FT3 level, and the FT3/FT4 ratio. At follow‑up, the FT3/FT4 ratio tended to normalize in patients with MI and remained decreased in patients with HF (mean [SD], 0.31 [0.06] vs 0.27 ([0.05]; P < 0.001. Conclusions: Se deficiency is very common in Polish patients with MI and HF. Thyroid hormones disturbances were more transient in patients with MI, but more chronic in those with HF