Few studies reported on the prevalence of MetS in AF population are still lacking. Some data can be inferred from studies regarding recurrence of AF after catheter ablation reporting a prevalence ranging from 18.8% to 49.4% . The only population study so far published included 741 chinese patients and reported a prevalence of the MetS in AF of 46.3%. Taking into account the different thresholds of waist circumferences recommended by international societies for different ethnic groups, it is unclear if such prevalence can be extrapolated to population of western countries. Furthermore the impact of MetS on the incidence of cardiovascular events in patients with non valvular AF (NVAF) taking oral anticoagulant therapy (OAT) has never been investigated.