This study illustrated that the level of miR-106 in the AF group was markedly larger than that in the control, and the level of MYL4 was notably less than that control, suggesting that the increased level of serum miR-106 and the decreased level of MYL4 may be involved in the risk of AF, and is closely related to the severity and prevalence of AF. Here, MYL4 is linked to atrial fibrillation.