Atrial fibrillation is the most common arrhythmia found in clinical practice. It also accounts for 1/3 of hospital admissions for cardiac rhythm disturbances, and the rate of admissions for AF has risen in recent years. Approximately 2.2 million individuals in the United States and 4.5 million in the European Union have AF. The incidence of atrial fibrillation increases with age. The prevalence in individuals over the age of 80 is about 8%. In developed countries, the number of patients with atrial fibrillation is likely to increase during the next 50 years, due to the growing proportion of elderly individuals.