Free triiodothyronine in relation to coronary severity at different ages: Gensini score assessment in 4206 euthyroid patients

Objective To study whether free triiodothyronine (FT3) within normal range has effects on the presence and severity of coronary artery disease (CAD) in different gender and age groups. Methods A total of 4206 euthyroid patients were consecutively enrolled and divided into CAD group (n = 3306) and non-CAD group (n = 900). All patients underwent coronary angiography (CAG). Gensini score (GS) was used to determine the severity of coronary artery stenosis. Severe CAD was defined as GS > 32 and mild CAD was defined as GS ≤ 32. Logistic regression analysis and linear regression analysis were conducted to determine the association of FT3 with CAD in patients with different gender and ages. Results Concentration of FT3 was lower in patients with CAD than that in angiography-normal control group (P ? 0.05). In addition, concentration of FT3 was lower in severe CAD than that in mild CAD. After adjusting for traditional cardiovascular risk factors and potential confounders, FT3 was negatively correlated with the presence of CAD, but not in the old patients (? 65 years old). Multivariable linear regression analysis showed that FT3 was negatively associated with GS in male and young patients with stable CAD, but not in the old patients. Conclusions Low FT3 within normal range was negatively associated with the presence and severity of CAD in young patients, but not in the old ones. Further studies are needed to confirm our findings.