Gradual power titration using radiofrequency energy: a safe method for slow-pathway ablation in the setting of atrioventricular nodal re-entrant tachycardia.

Aims: In the setting of atrioventricular nodal re-entrant tachycardia (AVNRT), radiofrequency (RF) catheter ablation of the slow-pathway (SP) ensures excellent outcome. However, the risk of complete heart block (CHB) remains real ( approximately 1%) and detrimental. This study reports on a gradual power titration approach using RF energy, which allows a significant decrease in CHB occurrence.

Methods And Results: Slow-pathway ablation was performed in 468 patients (mean age 43.8 +/- 17.2 years, 311 women). Initial settings were 5 W, 60 degrees C, 120 s (temperature-controlled mode). The power was increased by steps of 5 W for every 5 s until slow-accelerated junctional rhythm was obtained, and then further increased to 10 W maximum above this value. The acute success rate, the mean RF pulses applied per patient, and the average power delivered per successful RF applications were 99%, 3.2 +/- 1.1, and 31.7 +/- 3.0 W, respectively. There were nine (1.9%) transient and reversible AV blocks, and one (0.2%) permanent CHB only necessitating pacemaker insertion. The recurrence rate was 3.6% and the follow-up period was 28.1 +/- 14.1 months.

Conclusion: Atrioventricular nodal re-entrant tachycardia RF ablation using gradual power titration is an efficient technique, capable of improving safety since it can decrease CHB occurrence.