Atrial fibrillation is a heart condition in which the upper chambers of the heart (the atria) beat irregularly and too fast because they receive extra, "abnormal" electrical signals. This causes the atria to quiver (fibrillate), affecting the heart's ability to pump blood to the body. As a result, your brain and other organs may not be getting the full blood supply they need.
AFib becomes more difficult to treat over time. It can lead to irreversible heart damage or the formation of blood clots inside the heart, which in turn may lead to a stroke. AFib causes about 1 in 7 strokes.
AFib can be detected through an electrocardiogram (EKG or ECG) that records electrical signals generated by the heart. A Holter monitor may also be worn for one or more days to detect AFib, and more recently, wearable technology such as SmartWatches may also help detect when someone is in AFib.