Introduction:
The energy applied under temperature control (TC) has a more predictable effect than the one applied under power control. The currently introduced cooled-tip DiamondTemp catheter (DT) restores the ability to adjust radiofrequency (RF) power to the temperature at the electrode-tissue interface. It also enables high-power (HP) ablation procedures. Aim of the study was to assess how often ablation with TC at a 50 W nominal setting meets HP ablation criteria. We analyzed the influence of the learning curve on the results.

Material and methods:
The course of 3350 applications performed using DT in 20 patients (14 M, age 55 ±13 years) with atrial fibrillation/left atrial flutter was analyzed. 24 applications with 1–2 s duration were excluded. Average (P_avg), minimal (P_min), and maximal (P_max) power were evaluated. The percentage of applications > 45 and > 50 W (P_min > 49 W) was assessed.

Results:
From 3326 applications with the duration > 2 s only 1430 (43%) were between 3 and 10 s (excellent catheter/muscle contact). There was an insignificant trend to increase the percentage of short applications during the learning curve (p = 0.054). P_min > 45, > 49 or > 50 W was recorded during 3130 (94.1%), 2963 (89.1%) and 98 (1.1%) applications, respectively. P_avg 45 or 50 W was recorded during 3230 (97.1%) and 2700 (81.2%) applications, P_max during 3296 (99.1%) and 3269 (98.3%) applications. The percentage of applications with P_avg and P_min > 45/> 50 (49) W (but not P_max) significantly decreased during the procedures in the second subgroup of patients.

Conclusions:
P_max seems not to be as good a criterion for classification of application as HP. Most TC applications performed with the DT meet the criteria for HP ablation. The learning curve impacts the percentage of HP applications.