Safety verification of a novel irrigation catheter with flexible tip of laser‐cut kerfs and contact force sensor

Abstract Background and aims The safety evaluation of TactiFlex, a novel contact‐force sensing catheter with a flexible 4‐mm tip irrigated through laser‐cut kerfs, has been ongoing. This study aimed to verify the safety of this type of catheter. Methods Study 1: Radiofrequency (RF) applications at a range of powers (30–50 W), contact forces (10–20 g), and durations (10–60 s) using perpendicular/parallel catheter orientation with half‐normal (HNS) or normal saline irrigation were compared between TactiFlex (4‐mm tip) and TactiCath (3.5‐mm tip) with temperature‐controlled mode in excised porcine hearts. Study 2: The relation between RF applications using TactiFlex and the incidence of steam‐pops in the real clinical cases were examined. Results Study‐1: 576 RF lesions were examined. TactiFlex demonstrated a significantly lower risk of steam‐pops (5[1.7%] vs. 59[20.5%], p < .0001). Compared to 3.5‐mm‐tip catheter (TactiCath), 4‐mm‐tip catheter (TactiFlex) produced smaller lesion volume at perpendicular (193[98–554]mm 3 vs. 263[139–436]mm 3 , p < .0001), but relatively similar lesion volume at parallel contact (243[105–443]mm 3 vs. 278[180–440]mm 3 , p = .06). HNS‐irrigation tended to increase the lesion volume in both catheters and to increase the incidence of steam‐pops with TactiCath, but not with TactiFlex. The cut‐off value of %impedance‐drop ( = absolute impedance‐drop/initial impedance) of 20% predicted steam‐pops with a sensitivity = 100% and specificity = 89.6% in TactiFlex. Study‐2: 5496 RF applications in 84 patients (51AFs/8ATs/3AVNRTs/4AVRTs/17PVCs/4VTs) using TactiFlex were analyzed. Four steam‐pops (0.07%) in three patients with pericardial effusion were observed (%impedance‐drop = 24%/26%/29%/35%, respectively). The cut‐off value of %impedance‐drop = 20%, derived from ex‐vivo study, showed sensitivity = 100% and specificity = 90.1% in detecting steam‐pops. Conclusion TactiFlex reduced the risk of steam‐pops than TactiCath. %impedance‐drop ≤ 20% may be reasonable for safely use with a sufficient safety margin. For 4‐mm‐tip catheter, parallel‐contact may be recommended for larger lesion creation.