A previous study indicated that serum MIF concentrations are elevated in patients with AF.3,11 In this study, we investigated the effects of MIF on PV tissue and observed that MIF (100 ng/mL) increased PV tissue beating rate and the spontaneous triggered activity and led to a higher incidence of premature atrial beats, indicating that MIF may increase PV arrhythmogenesis, which may partially contribute to AF genesis. Here, MIF is linked to atrial fibrillation.