Atrial fibrillation (AF) is a common arrhythmia that may or may not be associated with underlying organic heart disease. In the past, the most common cause of AF was rheumatic valvular heart disease with mitral valve involvement and left atrial enlargement. With the near elimination of rheumatic fever, other cardiac disorders such as hypertensive heart disease, coronary disease, and cardiomyopathy are the predominant causes of AF. In addition, this arrhythmia may occur in the absence of significant heart disease and may develop as a result of intra-atrial conduction disturbance or from atrial reexcitation in association with accessory atrioventricular nodal conduction pathways of the reentrant type. Also, primary AF increases in frequency with advancing age such that 5% of patients in the over-70 age group have this arrhythmia.
Atrial fibrillation with the loss of synchronized atrial contraction has important hemodynamic consequences. Cardiac output may be reduced by 10% or more