A Retrospective Register Study to Map the Frequency of Short Duration Atrial Fibrillation (AF) Among All Patients Admitted to Roskilde Sygehus in Denmark in 2010

The study is a retrospective register study of all patients discharged from Roskilde Hospital with a primary diagnosis of AF in 2010. All data will be collected from the patient's medical records and only data from this specific admission will be recorded. No follow-up of the patients after discharge will be performed in this study. The study does not involve any randomization or any drug testing.