Wolff-Parkinson-White (WPW) syndrome is a relatively common heart condition that causes the heart to beat abnormally fast for periods of time. The cause is an extra electrical connection in the heart. This problem with the heart is present at birth (congenital), although symptoms may not develop until later in life. Many cases are diagnosed in otherwise healthy young adults. Sometimes the extra electrical connection won’t cause any symptoms and may only be picked up when an electrocardiogram (ECG) test is carried out for another reason. In these cases, further tests will be done to determine if treatment is required.