A new study published in Heart Rhythm reported more effective results when repeated radiofrequency catheter ablation (RFCA) for atrial fibrillation, using stronger contact force (CF) and higher power levels, was performed, especially in areas with high baseline local impedance (LI). 

Researchers analyzed data from 48 patients (average age 70, 48% female) undergoing repeat atrial RFCA. They examined 1,390 RFCA points and focused on 309 high-quality local electrograms to assess the effectiveness of the ablation. Effectiveness was measured by changes in electrical signals and the drop in LI during ablation.

The researchers reported that 40.5% of the ablation points showed clear signs of effectiveness, with a significantly greater LI drop (19.7 ohms) compared to less effective areas (14.1 ohms). Contact force was most strongly associated with LI drop when both baseline LI was high and power was set to 40 watts or more. In these conditions, the correlation was very strong (R = 0.72). In areas with lower baseline LI, the effect of CF on LI drop was smaller.

Across all settings, using a mean contact force of at least 10 grams consistently resulted in better LI drops, especially when combined with higher power.