Atrial fibrillation is where the top half of my heart isn't beating with the rest of my heart resulting in an irregular heartbeat. I hate being more tired and being short of breath because my heart isn't pumping enough blood. I also have to take Coumadin for a blood thinner to take care of any blood clots that might form. I have to have my blood tested twice a week for the next six months! This disease is the pits, but I'm still alive and on PT!