OBJECTIVES: This study investigated the outcomes and management associated with stroke prevention treatments in patients with non-valvular atrial fibrillation (NVAF) in Europe. The primary objective of this analysis was to assess the management of patients treated with vitamin K antagonists (VKA). METHODS: We conducted an observational retrospective cohort study of patients with NVAF in the Longitudinal Patient Database (CEGEDIM) in France, Italy, the UK, Spain and Germany. The analysis included patients >=18 years old with recorded AF diagnosis, treated with VKA, and without rheumatic valvular disease or prosthetic valves prior to the index date (date of 1stvisit during inclusion period – May 2010 to April 2012 - , or date for first AF diagnosis, if this falls during this period.  Only patients with >=1 year of data were included to ensure adequate data availability. Using recorded INR measures, we estimated the average time within therapeutic range (TTR), INR between 2 and 3 for patients eligible to apply the Rosendaal Method. RESULTS: In France 1,110 patients were assessed, in Germany 1,208, in Italy 1,230, & the UK 2,702. Insufficient data were retrieved in Spain (n=12). INR was measured 9.6 times/year in France, 9.5 times/year in Germany, 9.8times/year in Italy, and 13.1 times/year in the UK. In France, 48% of the patients had TTR >=70% of their time; in Germany, 44%; in Italy, 46%, and in the UK, 65%. CONCLUSIONS: Treatment outcomes with VKAs, in particular stroke and bleeding, depend on maintaining patients’ INR values within recommended range. The results show that the majority of patients in France, Germany and Italy, & 1/3 of patients in UK did not achieve recommended TTR and therefore were at increased risk of stroke or major bleeding. Further research is needed to demonstrate the correlation between these estimates and stroke and major bleeding rates within countries.