Pre-Excited Atrial Fibrillation in Wolff-Parkinson-White (WPW) Syndrome: A Case Report and a Review of the Literature

Fig. 1.. The first collected electrocardiogram (ECG) at the emergency department admission depicted a mildly wide complex tachycardia with a slurred QRS upstroke and slightly irregular cycle length. The initial differential diagnosis included antidromic atrioventricular re-entry tachycardia (AVRT), atypical AV node re-entry tachycardia (AVNRT) with a bystander accessory pathway (RP not compatible with typical AVNRT), atrial tachycardia (AT) or atrial flutter conducted through an accessory pathway (possibly with 2:1 conduction), or theoretically any supraventricular tachycardia (SVT) with aberrancy due to phase-3 bundle branch block.

Fig. 2.. The ECG monitoring revealed phases of irregular tachycardia cycle lengths, thereby confirming pre-excited atrial fibrillation. Utilizing algorithms capable of predicting accessory pathway (AP) location, the ECG suggested the presence of a left lateral AP. Identifying the correct location is best achieved when there is maximal pre-excitation, as observed in this tracing. ECG, electrocardiogram.

Fig. 3.. The ECG during sinus rhythm displayed a short PR interval (90 msec) and a mild delta wave, which was more pronounced in the inferior leads. ECG, electrocardiogram.

Fig. 4.. A 3D mapping reconstruction was utilized to illustrate the left lateral localization of the accessory pathway (latero-lateral view). This 3D map, obtained with the CARTO system (Biosense Webster, Inc., Irvine, CA, USA), highlights the precise radiofrequency delivery locations. The red and pink dots on the map represent the targeted zone, with red dots indicating areas with a higher ablation index compared to the pink dots. 3D, three-dimensional.