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

PURPOSE: The QDOT-MicroTM 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-MicroTM (TFC-ablation) and Thermocool SmartTouch SFTM (PC-ablation).

RESULTS: Both TFC-ablation and PC-ablation produced similar lesions in volume (218±116 vs 212±107 mm3 , p=0.65); however, lesions using TFC-ablation were larger in surface area (41.3±8.8 vs 34.8±8.0 mm2 , p<0.001) and shallower in depth (4.0±1.0 vs 4.2±1.1 mm, p=0.044). Average power tended to be lower in TFC-alation (34.2±8.6 vs 36.9±9.2, p=0.005) 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=0.021), they were particularly observed in low-CF (10g) and high-power ablation (50W) 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. This article is protected by copyright. All rights reserved.