The investigation of the tolerability and the cost, due to the drug change to novel oral anticoagurants (rivaroxaban) from warfarin in patients with nonvalvular atrial fibrillation in the perioperative period

INTERVENTION: Xarelto is administered to patients at the dose of 15mg/day. CONDITION: Nonvalvular Atrial Fibrillation PRIMARY OUTCOME: 1)Inpatient days; 2)In‐hospital medical expense (including outpatient therapy) SECONDARY OUTCOME: Tolerability (existence or nonexistence of hemorrhage and orischemic events) INCLUSION CRITERIA: 1)The patients with nonvalvular atrial fibrillation who are scheduled to undergo surgery recommended to use Heparin 2)Patients who received sufficient explanation before participation in this study, understood it and gave written consent based on their free will