Ninety seconds could be the optimal duration for ventricular radiofrequency ablation: results from a myocardial phantom model

Background: Shallow lesions could be the predominant factor affecting the efficacy of ventricular radiofrequency (RF) ablations. The objective of this study was to assess lesion dimensions and overheating in extended RF ablations up to 180 seconds and compare with that of conventional 30 seconds ablations.

Methods: The Navistar Thermocool irrigated catheter (Biosense Webster, CA, USA) was used in a previously validated myocardial phantom. Ablations were performed with 20W, 30W, 40W and 50W powers for 180seconds. The volume of lesion and overheating were measured at 53°C and 80°C isotherms respectively.

Results: A total of 110 RF lesions were analysed. The lesion depth increment when ablation was extended from the conventional 30 seconds to 90 seconds were 31.2±0.2, 33.6±0.6, 36.3±1.8% of that at 30 seconds, respectively for powers 30W, 40W and 50W. During 30W ablations, at 90 seconds the lesion width and depth were 95.4±1.2%, 91.8±1.6% respectively of the final dimensions at 180 seconds. Similar proportions were observed for 40W and 50W. During 40W ablations, the volume of overheating was 113±6% and 184±11% higher at 90 seconds and 180 seconds respectively compared to that at 30 seconds and was 142±9% and 194±9% for 50W ablations.

Conclusion: Extending RF ablations up to 90 seconds significantly increased the lesion depth (30-40%), however, overheating was present at 40W and 50W powers. Ablations beyond 90 seconds provided little incremental value.