New-onset arrhythmias are a common complication of cardiac surgery. Atrial fibrillation is the most common arrhythmia encountered postoperatively, although ventricular arrhythmias and conduction disturbances can also occur. Postoperative arrhythmias are an important cause of increased morbidity, prolonged hospitalization, and higher medical costs. Prophylactic pharmacological and non-pharmacological treatments are highly useful in avoiding these problems.