Radiofrequency ablation of atrial insertion of left-sided accessory pathways guided by the "W Sign"

The aim of this study was to evaluate the efficacy of radiofrequency (RF) ablation of the atrial insertion of left-sided accessory pathways with guidance by a specific morphologic characteristic of the local electrogram, which we call the "W sign." This represents the shortest local atrioventricular (AV) interval during sinus rhythm in patients with manifest preexcitation or the shortest local VA interval during AV reciprocating tachycardia and/or ventricular pacing in patients with concealed accessory pathways.

The transseptal technique was used in 31 patients (18 men, 13 women; aged 32 +/- 13 years), and RF ablation of 33 accessory pathways (26 manifest and 7 concealed) was attempted. Patients presented with palpitations (n = 16), presyncope (n = 10), or syncope (n = 5). The clinical arrhythmia was AV reciprocating tachycardia (n = 24) or atrial fibrillation (n = 7). In 21 patients (68%) electrophysiologic study and RF ablation were performed at a single session. Accessory pathways were left posteroseptal (n = 5) or left free wall (n = 28). The "W sign," formed from merging of the local atrial and ventricular electrograms, was identified at all successful sites prior to ablation. Ablation was successful in all patients. A median of 7 RF lesions were delivered per patient. The fluoroscopy time was 76 +/- 48 minutes; total procedure time was 5.4 +/- 1.9 hours. No significant complications occurred. Early recurrence (< or = 24 hours) occurred in 1 patient; during 6 +/- 4 months, accessory pathway conduction recurred in another patient.

We conclude that RF ablation of the atrial insertion of left accessory pathways can be very successful when guided by the "W sign."