Interactions of contact force, impedance, and power during repeated atrial arrhythmia ablation after previous atrial fibrillation ablation.

Background: Acutely effective repeated radiofrequency catheter ablation (RFCA) after previous atrial fibrillation ablation depends on several parameters including local impedance (LI), contact force (CF), and power.

Objective: We aimed to investigate the relationship of LI, CF, and power to the LI drop in a repeated atrial RFCA environment.

Methods: Consecutive patients undergoing repeated atrial RFCA were studied. High-quality local electrograms were analyzed for morphology changes indicating effective RFCA and associated LI dynamics. The influence of baseline LI, mean CF, and power on the LI drop was analyzed. Investigated power levels included ≤25 W, 30 W, and ≥40 W.

Results: A total of 1390 RFCA points from 48 patients (48% female; median age, 70 years) were analyzed. Of 309 analyzed electrograms, 40.5% showed effective RFCA morphology changes with an elevated median LI drop (effective, 19.7 Ω; partially effective, 14.1 Ω; P < .001). CF showed the highest correlation to the LI drop within high baseline LI and when applying ≥40 W (low baseline LI, R = 0.39; intermediate, R = 0.66; high, R = 0.72). Within low baseline LI regions, CF levels showed a lower correlation to the LI drop (≤25 W, R = 0.30; 30 W, R = 0.35; ≥40 W, R = 0.39). A mean CF ≥10 g resulted in elevated LI drops with higher power compared with lower power within all baseline LI tertiles (P < .001 each).

Conclusion: Within high baseline LI regions, CF plays a greater role for the maximum LI drop when higher power is chosen. A mean CF ≥10 g ensures elevated LI drops with increasing power levels.