Symptoms. The most prominent symptoms that result from atrial fibrillation include heart palpitations. These are where the individual feels the heart is beating too hard or fast and lightheadedness from lack of oxygen supply to the brain. Other symptoms include pain in the chest, dizziness, fatigue, confusion, loss of consciousness, inability to exercise, and shortness of breath. Most symptoms are a result of oxygen deprivation due to the heart not effectively pumping oxygenated blood to the brain, lungs, and other regions of the body because of the atrial fibrillation.