Atrial fibrillation (AF or A-fib) is the most common cardiac arrhythmia (heart rhythm disorder). It may cause no symptoms, but it is often associated with palpitations, fainting, chest pain, or congestive heart failure. However, in some people, atrial fibrillation is caused by otherwise idiopathic or benign conditions.
AF increases the risk of stroke. The degree of increase can be substantial, depending on the presence of additional risk factors (such as high blood pressure). It may be identified clinically when taking a pulse, and the presence of AF can be confirmed with an electrocardiogram (ECG or EKG), which demonstrates the absence of P waves together with an irregular ventricular rate.
In AF, the normal regular electrical impulses generated by the sinoatrial node are overwhelmed by disorganized electrical impulses usually originating in the roots of the pulmonary veins, leading to irregular conduction of impulses to the ventricles, which generate the heartbeat. AF may occur in episodes lasting from minutes to days (“paroxysmal”), or be permanent in nature. A number of medical conditions increase the risk of AF, particularly mitral stenosis (narrowing of the mitral valve of the heart).
Atrial fibrillation may be treated with medications to either slow the heart rate to a normal range (“rate control”) or revert the heart rhythm back to normal (“rhythm control”). Synchronized electrical cardioversion can be used to convert AF to a normal heart rhythm. Surgical and catheter-based therapies may be used to prevent recurrence of AF in certain individuals. Depending on the risk of stroke and systemic embolism, people with AF may use anticoagulants, such as warfarin, which substantially reduces the risk but may increase the risk of major bleeding, mainly in geriatric patients. The prevalence of AF in a population increases with age, with 8% of people over 80 having AF. Chronic AF leads to a small increase in the risk of death.