Ablation protocol
To obtain a range of lesion sizes, myocardial lesions were created at separate sites with contact force set at 5, 15 and 25g, and power settings set at 20, 30 and 40 W. For each contact force and power setting, RF delivery was delivered for 10, 20, 30, 45 and 60 seconds. The catheter was placed perpendicularly and parallelly to the tissue (Figure 1B). Three lesions for each combination of settings were created (270 lesions for each catheter). After creating every lesion, the ablation electrode and the electrode–tissue interface were examined for char formation. The incidence of an audible pop was noted.