LAUSR

Abstract Funding Acknowledgements Type of funding sources: None. Background Ultra-high-power short-duration (UHPSD) ablation with the novel QDOT™ catheter allows to maintain a target temperature by automatically adjusting flow and power during a 4-second application of 90 Watt. However, the optimal contact-force for a sufficient lesion generation is yet to be determined. Methods This study comprised 41 patients with symptomatic atrial fibrillation undergoing pulmonary vein isolation (PVI) with the QDot catheter using the UHPSD mode with 90 W for 4 seconds. All UHPSD applications for circumferential PVI were analyzed. Suboptimal UHPSD applications were defined as either an impedance drop of ≤5% or a cumulative temperature-limited energy ≤330 W. Results A total of 1904 UHPSD applications (46.4 applications per patient) were performed with an average contact force (aCF) of 12.3±6.4 g with a mean maximum temperature (maxTemp) of 48.4±3.8 °C and a mean impedance drop (ImpDrop) of 10±3.2%. An ImpDrop ≤5% occurred in 67 (3.5%) UHPSD applications which was associated with lower aCF (10.6±7 vs. 12.4±6.4 g; p=0.024) and a lower maxTemp (45.8±3.8 vs. 48.5±3.8 °C; p<0.001) as compared to UHPSD applications with an ImpDrop >5%. A cumulative energy ≤330 W was observed in 39 (2%) UHPSD applications. Interestingly, low cumulative energy UHPSD applications (≤330 W) were characterized by a higher aCF (21±9.6 vs. 12.1±6.2 g; p<0.001). Furthermore, low cumulative energy was observed significantly more often in UHPSD applications with aCF <5.6 g or >21.1 g (10.2% vs 3.6%; p=0.004). Conclusion A low but also a high contact-force (<6 and >21g) are associated with suboptimal UHPSD applications. Thus, UHPSD applications require a ’15-gram window’ of contact-force to achieve an optimal cumulative energy.