Subgroup analysis showed that there was no significant interaction between fT3 levels and age (<65 years or ≥65 years), sex, traditional cardiovascular risk factors (hypertension, diabetes mellitus, smoking, BMI, and atrial fibrillation), LVEF, cTnT, NT-proBNP levels, and the number of vessel diseases (all P for interaction > 0.05). This evidence concerns the gene TNNT2 and atrial fibrillation.