Atrial fibrillation occurs when the top part of the heart, called the atria, beats at around 300 beats per minute and leads to ineffective contraction of the atria. This predisposes to clots forming in the left atrium that can break off and travel to the brain and block circulation and result in strokes. Anticoagulation is the treatment of choice but there is considerable controversy about how to do this. Coumadin, aspirin, Plavix, fish oil, and nattokinase are discussed.