INAPPROPRIATE SINUS TACHYCARDIA AFTER RADIOFREQUENCY ABLATION OF PARA-HISIAN ACCESSORY PATHWAYS

Introduction: Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinic al significance of IST following RFA of para-Hisian accessory pathways (APs). Methods and Results: Twenty-eight patients (pts) with para-His ian APs underwent RFA, An AP was defined as para-Hisian whenever its a trial and ventricular insertions were associated with a His-bundle pot ential greater than or equal to 0.1 mV, RF current was always delivere d at the atrial aspect of the tricuspid annulus, to a site where the H is-bundle potential was < 0.15 mV, Time-and frequency-domain analysis of heart rate variability was performed in 22 patients, before and aft er RFA, Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred, Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure, In 5 of them, IST disappe ared spontaneously within 72 hours, whereas in 1 pt beta-blockers were required for 2 months. The atrial potential amplitude (1.217 +/- 0.26 4 mV vs 0.882 +/- 0.173 mV, P = 0.009) and AN potential amplitude rati o (2.633 vs 1.686, P = 0.05) were significantly higher in pts who deve loped IST than in those who did not. A marked decrease in heart rate v ariability was observed only in pts who developed IST. Conclusion: IST is a relatively frequent complication after RFA of para-Hisian APs: i t is generally short-lasting and usually does not require any treatmen t. IST after catheter ablation is likely to depend upon transient para sympathetic denervation of the sinus node.