Atrial fibrillation (AF) usually causes the hearts lower chambers, the ventricles, to contract faster than normal. When this happens, the ventricles cant completely fill with blood. Thus, they may not be able to pump enough blood to the lungs and body. This can lead to signs and symptoms, such as: Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast) Shortness of breath Weakness or problems exercising Chest pain Dizziness or fainting Fatigue (tiredness) Confusion Atrial Fibrillation Complications AF has two major complicationsstroke and heart failure. Stroke During AF, the hearts upper chambers, the atria, dont pump all of their blood to the ventricles. Some blood pools in the atria. When this happens, a blood clot (also called a thrombus) can form. If the clot breaks off and travels to the brain, it can cause a stroke. (A clot that forms in one part of the body and travels in the bloodstream to another part of the body is called an embolus. ) Blood-thinning medicines that reduce the risk of stroke are an important part of treatment for people who have AF. Atrial Fibrillation and Stroke Heart Failure Heart failure occurs if the heart cant pump enough blood to meet the bodys needs. AF can lead to heart failure because the ventricles are beating very fast and cant completely fill with blood. Thus, they may not be able to pump enough blood to the lungs and body. Fatigue and shortness of breath are common symptoms of heart failure. A buildup of fluid in the lungs causes these symptoms. Fluid also can build up in the feet, ankles, and legs, causing weight gain. Lifestyle changes, medicines, and procedures or surgery (rarely, a mechanical heart pump or heart transplant) are the main treatments for heart failure. 
What are the symptoms of Atrial Fibrillation ?