Atrial fibrillation (AF) is the most common type of arrhythmia. An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. People who have AF may not feel symptoms. However, even when AF isn’t noticed, it can increase the risk of stroke. In some people, AF can cause chest pain or heart failure, especially if the heart rhythm is very rapid.
Click here for more information. http://www.nhlbi.nih.gov/health/health-topics/topics/af/