A common heart rhythm disorder is atrial fibrillation. One in three 55-year-olds can expect to develop atrial fibrillation during their lifetime. In atrial fibrillation, the heart beats irregularly and often too fast. Atrial fibrillation does not always cause symptoms, and up to 1 in 3 people with atrial fibrillation have the condition without knowing it. Atrial fibrillation increases the risk of blood clots forming in the heart. Such blood clots can follow the large blood vessels to the brain and cause a stroke. The risk of stroke due to atrial fibrillation increases with age >65 years, diabetes, high blood pressure and other cardiovascular diseases. Anticoagulation therapy effectively reduce the risk of stroke in those with atrial fibrillation, and are recommended for most people with atrial fibrillation. Atrial fibrillation is easily detected with an ECG test. Long-term recording of the ECG increases the possibility of detecting paroxysmal atrial fibrillation.