If you are experiencing episodes of a racing heart or extreme fluttering, you could have a serious condition called atrial fibrillation, which is often referred to as AFib. Atrial fibrillation is the most common type of treated heart arrhythmia. An arrhythmia is when the heart beats too slowly, too fast, or in an irregular way. When a person has AFib, the normal beating in the upper chambers of the heart is irregular, and blood doesn’t flow as well as it should from the atria to the lower chambers of th...