RANDOMIZED COMPARISON OF 2 TECHNIQUES FOR TITRATING POWER DURING RADIOFREQUENCY ABLATION OF ACCESSORY PATHWAYS

Impedence Versus Temperature Monitoring. Introduction: The purpose of this study was to prospectively compare the value of impedance and tem perature monitoring during accessory pathway ablation. Temperature and impedance monitoring can be used during radiofrequency ablation of ac cessory pathways to titrate power to achieve adequate but not excessiv e tissue heating. Methods and Results: One hundred thirty-two patients with a single accessory pathway were randomly assigned to undergo abl ation using either impedance monitoring or temperature monitoring. Dur ing impedance monitoring, the endpoint for titration of power was a 5- to 10-Omega decrease in the measured impedance while for temperature monitoring the endpoint was to achieve a temperature of 58 degrees to 62 degrees C. Two protocols were used. In protocol 1 (90 patients), im pedance monitoring was performed with a nonthermistor catheter and tem perature monitoring was performed with a thermistor catheter. In proto col 2 (42 patients), a thermistor catheter was used in all patients. I n protocol 1, the success rate (93% vs 93%; P = 1.0), ablation procedu re duration (57 +/- 56 vs 41 +/- 41 min), fluoroscopy time (48 +/- 29 vs 41 +/- 23 min; P = 0.3), number of applications (6.2 +/- 4.7 vs 5.7 +/- 4.6; P = 0.8), and the number of applications associated with coa gulum formation (0.1 +/- 0.3 vs 0.3 +/- 0.6; P = 0.1) were similar in the two groups. In protocol 2, as in protocol 1, there were no differe nces in the success rate (91% vs 95%; P = 1.0), ablation procedure dur ation (49 +/- 37 vs 62 +/- 55 min; P = 0.4), fluoroscopy time (46 +/- 24 vs 49 +/- 36 min; P = 0.8), number of applications (6.8 +/- 7.0 vs 7.8 +/- 12.1; P = 0.7), or number of applications associated with coag ulum formation (0.3 +/- 0.6 vs 0.2 +/- 0.7; P = 0.6) between the imped ance and temperature monitoring groups. Conclusion: Temperature and im pedance monitoring are equally effective in optimizing the results of accessory pathway ablation.