Also known as preexcitation syndrome, Wolff-Parkinson-White (WPW) syndrome is a condition in which there is an extra, abnormal electrical pathway in the heart that can cause an abnormal heart rhythm (arrhythmia). The condition is believed to be present from birth (a congenital heart defect). In most cases, WPW causes symptoms only when the heart rate is very fast (tachycardia). In other cases, the condition may cause no symptoms at all. However, some WPW patients carry a small risk of developing a potentially fatal heart rhythm known as ventricular fibrillation.

Some individuals do not need treatment for WPW, either because they have no symptoms or because the condition resolves on its own as patients get older. Other cases will require treatment, including an invasive procedure called catheter ablation that destroys the abnormal pathway.  In rare cases, patients may need open-heart surgery. Medications (e.g., antiarrhythmics) may also be prescribed.