Aulin et al. (2015) concluded that in patients with AF, high IL-6 level is related to thromboembolism and major bleeding and is an independent risk factor for thromboembolic events. Although the mechanism of IL-6 in the pathogenesis of AF is not clear, studies (Marcus et al., 2008) have shown that IL-6 promotes MMP-2 secretion and is linked to left atrial enlargement, which is a known risk factor for AF. Here, IL6 is linked to Left atrial enlargement.