 Better Life with Dr. Sanjay Gupta. Atrial fibrillation, or AFib, it's a type of irregular heartbeat that's pretty common and becoming even more common. Now, in some people, AFib doesn't have any symptoms, but other people might experience chest pain, heart palpitations, shortness of breath, fatigue. AFib is also the leading cause of stroke in the United States, and according to the CDC, strokes linked to AFib