PURPOSE OF REVIEW: Rapid atrial arrhythmias affect the elderly who undergo cardiac or noncardiac operations annually and have been associated with prolonged hospital stays. This article focuses on new issues leading to the improved understanding of the pathophysiology and mechanisms of postoperative atrial arrhythmias. RECENT FINDINGS: New risk factors and a prediction rule for postthoracotomy atrial fibrillation are discussed. Settings in which amiodarone prophylaxis against atrial fibrillation after cardiac surgery is appropriate are contrasted with evidence for postthoracotomy atrial fibrillation. Once atrial fibrillation develops, rate versus rhythm control strategies are reviewed. The most recent recommendations of the American Heart Association Task Force on the management of patients with atrial fibrillation are highlighted. SUMMARY: Recent approaches directed at prophylaxis and acute therapy of atrial arrhythmias are discussed as are recommendations to prevent thromboembolic events.