Atrial fibrillation (AF) is the most common arrhythmia to occur after cardiac surgery. It is associated with postoperative complications including increased risk of stroke, prolonged hospital stay and increased costs. The study consisted of three randomized, prospective trials. In the first study intravenous metoprolol showed to be more effective than oral metoprolol in the prevention of AF after cardiac surgery. In the second study intravenous hydrocortisone reduced the risk of postoperative AF by 37% compared with placebo. In study three intravenous metoprolol therapy showed to be as effective as intravenous amiodarone in the prevention of postoperative AF after cardiac surgery.