Single Dose Flecainide for Early Sinus Rhythm Conversion of Perioperative Atrial Fibrillation After Noncardiac Surgery

Inclusion Criteria: * Age ≥ 18 years; * Noncardiac surgery in the last 30 days requiring an overnight hospital admission; * Presence of AF (i.e., atrial fibrillation and/or flutter) with a ventricular heart rate of ≥ 100 beats per minute at any time within 12 hours prior to randomization; * In AF at the time of randomization; AND, * Provided written informed consent. Exclusion Criteria: * History of AF without normal sinus rhythm documented within 90 days prior to randomization; * Hemodynamic instability; * Have any one of the following contraindications to flecainide: 1. known left ventricular ejection fraction ≤ 40%; 2. myocardial infarction within the last 30 days; 3. QRS interval \>140ms; 4. allergy to flecainide; 5. severe uncorrected hypokalemia (\<2.5 mEq/L) or hyperkalemia (\>6.5 mEq/L) at the time of randomization; 6. severe acute liver dysfunction or history of advanced cirrhosis; 7. severe renal insufficiency (eGFR ≤ 30ml/min or dialysis); OR, 8. second or third degree atrioventricular block within the last 30 days, in the absence of a pacemaker device; * Unable to take oral medication; * Previously enrolled in the trial.