They can be associated with forms of pre-excitation syndrome.

In all pre-excitation syndromes, at least one more conductive pathway is present.

Pre-excitation syndrome is a condition where the ventricles of the heart become depolarized too early, which leads to their partial premature contraction.

The condition is categorized as an electrical abnormality called pre-excitation syndrome and symptoms include rapid heart, dizziness, chest palpitations, fainting and sometimes cardiac arrest.

Wolff-Parkinson-White syndrome (WPW) is a pre-excitation syndrome in which individuals are predisposed to supraventricular tachyarrhythmias (rapid and irregular heart beats).

Wolff-Parkinson-White syndrome (WPW) is one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes.

A short PR interval may indicate a pre-excitation syndrome via an accessory pathway that leads to early activation of the ventricles, such as seen in Wolff-Parkinson-White syndrome.