F10 and atrial fibrillation: Afterward, we will summarize recent work on the role of coagulation factor serine proteases (thrombin and factor Xa) and protease-activated receptors (PARs) as determinants of atrial fibrosis, inflammation, and AF-related electrical abnormalities; with this regard, we will describe how novel anticoagulants, through inhibition of thrombin or factor Xa, may affect the pathophysiology of AF and alter disease progression.