Experimental Model
A circulating saline bath (400 mL/min, NaCl 3.5 g/L) isotonic to blood, a submersible load cell (KW-201, Tanita, Tokyo, Japan), and a deflectable sheath were assembled. The load cell was installed on the bottom of the bath with 5.0 L saline at 37°C, and a section of the left ventricular myocardium was placed on the ground plate on a load cell apparatus. CF applied to the overlying myocardial tissue through the ablation catheter was measured by the load cell in order to provide the same conditions between the TactiCathTM SE (which has direct CF-sensing capability) and FlexAbilityTM SE catheters. The accuracy of CF in this model was verified by a CF-sensing catheter with EnSite Precision (Abbott) mapping system as shown in Supplementary Figure 1. Briefly, the correlation coefficient between the CF measured by the load cell and CF in the TactiCathTMSE catheter was R = 0.97 for perpendicular catheter placement and R = 0.77 for parallel catheter placement. Temperature, power and impedance values were continuously monitored during RF delivery using the EnSite Precision cardiac mapping system.