Complete Atrioventricular Block

Relationship of P wave to QRS varies randomly. P waves are absent if there is atrial fibrillation. Escape rhythm may be junctional (narrow complex) or ventricular (broad complex). Even in asymptomatic patients, this carries a risk of sudden death due to ventricular standstill or polymorphic ventricular tachycardia/ventricular fibrillation. The escape rhythm is usually slower and less reliable when it is ventricular.