Comparison of lesion characteristics using temperature‐flow‐controlled versus conventional power‐controlled ablation with fixed ablation index

Abstract Introduction The QDOT‐Micro TM catheter is a novel irrigated contact force (CF) sensing catheter which benefits from thermocouples for temperature monitoring, allowing temperature‐flow‐controlled (TFC) ablation. We compared lesion metrics at fixed ablation index (AI) value during TFC‐ablation and conventional power‐controlled (PC)‐ablation. Methods A total of 480 RF‐applications were performed on ex‐vivo swine myocardium with predefined AI targets (400/550) or until steam‐pop occurred, using the QDOT‐Micro TM (TFC‐ablation) and Thermocool SmartTouch SF TM (PC‐ablation). Results Both TFC‐ablation and PC‐ablation produced similar lesions in volume (218 ± 116 vs. 212 ± 107 mm 3 , p = .65); however, lesions using TFC‐ablation were larger in surface area (41.3 ± 8.8 vs. 34.8 ± 8.0 mm 2 , p < .001) and shallower in depth (4.0 ± 1.0 vs. 4.2 ± 1.1 mm, p = .044). Average power tended to be lower in TFC‐alation (34.2 ± 8.6 vs. 36.9 ± 9.2, p = .005) compared to PC‐ablation due to automatic regulation of temperature and irrigation‐flow. Although steam‐pops were less frequent in TFC‐ablation (24% vs. 15%, p = .021), they were particularly observed in low‐CF (10 g) and high‐power ablation (50 W) in both PC‐ablation ( n = 24/240, 10.0%) and TFC‐ablation ( n = 23/240, 9.6%). Multivariate analysis revealed that high‐power, low‐CF, long application time, perpendicular catheter orientation, and PC‐ablation were risk factors for steam‐pops. Furthermore, activation of automatic regulation of temperature and irrigation‐flow was independently associated with high‐CF and long application time while ablation power had no significant relationship. Conclusions With a fixed target AI, TFC‐ablation reduced the risk of steam‐pops, producing similar lesions in volume, but with different metrics in this ex‐vivo study. However, lower CF and higher power in fixed‐AI ablation may increase the risk of steam‐pops.