Pre-excited atrial fibrillation
Pre-excited atrial fibrillation is atrial fibrillation in which ventricular activation is partially mediated by an accessory pathway, resulting in ventricular preexcitation on the electrocardiogram. [1] In this setting, rapid and irregular antegrade conduction over the accessory pathway can produce a wide-complex, irregular rhythm during atrial fibrillation. [1] This arrhythmia pattern is classically associated with Wolff-Parkinson-White (WPW) syndrome and can evolve into malignant tachyarrhythmias in some patients. [1]
Typical electrocardiographic features
Pre-excited atrial fibrillation is suggested by an irregularly irregular rhythm with beat-to-beat QRS morphology variability due to variable preexcitation. [2] Very short RR intervals during atrial fibrillation with evidence of ventricular preexcitation favor pre-excited atrial fibrillation over alternatives such as ventricular tachycardia. [2]
Clinical significance
Because accessory-pathway–mediated conduction during atrial fibrillation can accelerate ventricular activation, the presentation can deteriorate rapidly and may require urgent rhythm control. [1] Catheter ablation of the accessory pathway can eliminate ventricular preexcitation in affected patients. [1]