Patient selection. *Reasons for exclusion: 20 patients had indication for OAC treatment other than AF (VTE or secondary prevention of recurrent VTE) or previous diagnosis indicating valvular AF (mitral stenosis or mechanical heart valves); 5 patients had no documented weight; and 3 patients had no documented sCr level. Abbreviations: AF, atrial fibrillation; b.i.d., twice daily; OAC, oral anticoagulation; sCr, serum creatinine; VTE, venous thromboembolism