Abnormal heart rhythm characterized by rapid and irregular beating. Often it starts as brief periods of abnormal beating which become longer and possibly constant over time. Most episodes have no symptoms. Occasionally there may be heart palpitations, fainting, shortness of breath or chest pain. Atrial fibrillation increases the risk of heart failure, dementia and stroke. Hypertension and obesity are common risk factors for atrial fibrillation. Caffeine consumption does not appear to be associated with its development but excessive alcohol consumption (binge drinking) us linked to atrial fibrillation.