Safety of pacemaker implantation prior to radiofrequency ablation of atrioventricular junction in a single session procedure

RF current delivery may cause acute and chronic dysfunction of previously i mplanted pacemakers. The aim of this study was to assess prospectively the effects of RF energy on Thera I and Kappa pacemakers in 70 consecutive pati ents (mean age 70 +/- 11 years, mean left ventricular ejection fraction 48 +/- 15%) who underwent RF ablation of the AV junction for antiarrhythmic dr ug refractory atrial fibrillation (permanent in 42 patients, paroxysmal in 28). These pacing systems incorporate protection elements to avoid electrom agnetic interference. The pacemakers (Thera DR 7960 I in 20 patients, Thera SR 8960 I in 30, Kappa DR 600-601 in 8, Kappa SR 700-701 in 12) were impla nted prior to RF ablation in a single session procedure and at ere transien tly programmed to VVI mode at a rate of 30 beats/min. Capsure SP and Z unib ipolar leads were used. During RF application there was continuous monitori ng of three ECG leads, endocavitary electrograms, and event markers. Comple te AV block was achieved in all cases after 3.6 +/- 2.9 RF pulses and 100 /- 75 seconds of RF energy delivery. The mean lime of pacemaker implantatio n and RF ablation was 60 +/- 20 minutes. Transient or permanent pacemaker d ysfunction including under/oversensing, reversion to a "noise-mode" pacing, pacing inhibition, reprogramming, or recycling were not observed. Leads im pedance, sensing, and pacing thresholds remained in the normal range in the acute and long-term phase (average follow-up 18 +/- 12 months). In conclus ion, Thera I and Kappa pacemakers exhibit excellent protection against inte rference produced by RF current. The functional integrity of the pacemakers and Capsure leads was observed in the acute and chronic phases. Thus, the implantation of these pacing systems prior to RF ablation of the AV junctio n can be recommended.