Wolff-Parkinson-White syndrome (WPW) is the most common form of ventricular pre-excitation due to the presence of an accessory atrioventricular conduction pathway. This accessory pathway is called the bundle of Kent. The typical WPW ECG pattern is seen in approximately 0.13%-0.25% of the general population. Only 1%-1.8% of those with a WPW pattern on ECG develop arrhythmias. A familial form of WPW syndrome that is inherited in an autosomal dominant fashion has also been reported.

The accessory pathway is a thin filamentous tissue resulting from failure of atria and ventricles to completely separate; multiple pathways may exist in approximately 10% of patients. Associated congenital anomalies are seen in 7%-20% of patients, and about 10% of patients with Ebstein anomaly possess an aberrant pathway.

The accessory pathway predisposes patients to various supraventricular arrhythmias including atrioventricular reentrant tachycardia (AVRT), atrial fibrillation (AF), and atrial flutter. Extremely rapid ventricular rates sometimes seen in this setting can result in hemodynamic instability and degeneration to ventricular fibrillation.

Symptoms may include palpitations and/or syncope, chest pain, and sudden cardiac arrest, although most patients remain asymptomatic with incidental finding of the characteristic ECG pattern.