Symptoms of atrial fibrillation occur when the upper chambers of the heart (atria) beat in a disorganized fashion. Atrial fibrillation is a type of arrhythmia. Characteristic symptoms include shortness of breath, palpitations, and lightheadedness. In some cases, chest pain can be an associated symptom, particularly if there is also cardiovascular disease present. (Chest pain or pressure warrants urgent medical evaluation.) Other symptoms of atrial fibrillation are fatigue, confusion, and a reduced tolerance for exercise.

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