Temperature-controlled RF ablation with a QDOT catheter: a comparative study of lesion formation

Background Variability in lesion formation with high-power short-duration (HP-SD) and very high-power short-duration (vHP-SD) strategies—especially under different biophysical conditions—remains unclear. Evidence using a temperature-controlled catheter is limited. Objective To compare HP-SD and vHP-SD while accounting for key biophysical variables. Methods In a preliminary study with the Qdot Micro catheter, lesions were created in four porcine hearts using two protocols: 40 W for 40 s and 90 W for 4 s, across target temperatures from 40°C to 60°C. After ablation, tissue was cross-sectioned to measure lesion metrics. Impedance drop, temperature curves, and steam pops were also recorded. Results vHP-SD produced shallower and smaller lesions than the conventional setting (90 W/4 s vs 40 W/40 s: mean maximal depth 2.0 ± 0.5 vs 4.9 ± 0.4 mm; mean lesion volume 42.1 ± 15.4 vs 160.6 ± 49.4 mm³). With the 40 W/40 s protocol, lesion volume increased more with half-saline irrigation, highlighting its strong influence on lesion size. Notably, target temperatures >50°C were not achieved with the 90 W/4 s protocol. Moreover, even at similar AI values, lesion volume varied by temperature target in the 40 W/40 s protocol (40°C vs 47°C vs 50°C with half-saline irrigation: 145.1 ± 23.5 vs 171.2 ± 6.4 vs 251.6 ± 41.1 mm³; P = 0.008). Conclusion Modifying the temperature target has a greater effect on lesion metrics with conventional HP-SD ablation. In vHP-SD, lesion volume can be tuned by adjusting the irrigation solution rather than by increasing the temperature target.