Lesion metrics analysis of very high-power vs. high-power short duration radiofrequency ablation in a porcine ex vivo model

High-power, short-duration ablation (HP-SD) is a well-established protocol in electrophysiological procedures using radiofrequency (RF) energy. Recently, an alternative approach has become available, offering a very high-power, short-duration energy delivery (vHP-SD). This study aims to investigate the differences in lesion formation between a vHP-SD ablation protocol and a HP-SD protocol, with consideration of contact force levels, in a porcine ex vivo model.

RF ablations were performed on a porcine ex vivo model using cardiac ventricular muscle preparations in a circulating saline bath. Energy was applied according to two ablation protocols: vHP-SD (90 watts for 4 seconds) and HP-SD (50 watts for 15 seconds), delivered by an irrigated-tip ablation catheter. Ablations were conducted at six levels of contact force (CF: 5, 10, 15, 20, 25, and 30 g). The resulting lesions were analyzed macroscopically and compared in terms of depth, maximum diameter, and volume.

A total of 120 lesions (vHP-SD: 60, HP-SD: 60) were performed and analyzed. Lesion depth in both the vHP-SD (5g: 2.9 ± 0.3 mm to 30 g: 3.2 ± 0.3 mm; p = 0.061) and HP-SD protocols (5 g: 4.4 ± 0.7 mm to 30 g: 4.7 ± 0.7 mm; p = 0.224) showed no statistically significant increase with higher contact force (Figure 1A and 1B).

Similarly, maximum lesion diameter showed no notable variation with increased pressure in either protocol (vHP-SD: 5g: 7.5 ± 0.8 mm to 30g: 7.4 ± 1.1 mm; p = 0.995 / HP-SD: 5g: 9.0 ± 0.9 mm to 30g: 9.6 ± 1.5 mm, p = 0.693) (Figure 1C and 1D).

Lesion volume also remained consistent regardless of contact force in both protocols (vHP-SD: 5g: 92 ± 23 mm3 to 30g: 100 ± 31 mm3; p = 0.769 / HP-SD: 5g: 200 ± 59 mm3 to 30g: 246 ± 108 mm3; p = 0.520) (Figure 1E and 1F).

In direct comparison, lesions from the vHP-SD protocol were significantly shallower, narrower in diameter, and lower in volume than those from the HP-SD protocol (all p < 0.001).

Lesions created with the vHP-SD protocol are less extensive than those generated with HP-SD ablation, particularly in terms of depth, width, and volume. Increasing contact force has minimal effect on lesion metrics. Therefore, the vHP-SD protocol is better suited for areas with thinner myocardium, while the HP-SD protocol should be used when deeper lesions are needed.