Park J, et al. - In patients with non-valvular atrial fibrillation (AF), the value of platelet count (PLT) as a indicator of prognosis was assessed. They used a single medical center’s prospective registry in Korea to obtain the data of 10,978 patients with non-valvular AF. They derived prediction models for stroke by conventional risk factors (Model 1) and by combining PLT with Model 1 (Model 2). Using propensity score matching, they compared cumulative risk for stroke and bleeding events between patients with normal PLT (N=8,322), mild thrombocytopenia (N=1,791) and moderate to severe thrombocytopenia (N=865). A lower risk of stroke and a higher risk for bleeding events was observed in relation to a lower PLT. Adding PLT to conventional risk factors significantly improved prediction for stroke.