Fibrosis inhibits ablation lesion formation in muscle tissue

Abstract

Abstract Introduction Myocardial fibrosis is a trigger for both atrial and ventricular arrhythmia. Ventricular fibrosis correlates with ventricular tachycardia, ventricular fibrillation, and sudden death. Besides medical therapy, radiofrequency (RF) ablation is an important therapeutical option to treat ventricular arrhythmia. Our study gains insights into effectivity of RF ablation depending on the degree of fibrosis. Methods Using a wet lab, we created with radiofrequency (RF) ablation lesions in parts of restructured beef with a defined, homogenous content of 0, 10, 20 and 50% fiber. We calculated the volume of ablation zones (called lesion volume below). Both common ablation modes low-power long-duration (LPLD: 30 W, 30 s) and high-power short-duration (HPSD: 70 W, 10 s) were tested. Lesion volumes of fibrotic beef were compared to lesion volumes of fibrotic-free beef using an ordinary ANOVA. The effect and interaction of fibrosis and ablation mode to the lesion volume was tested by a two-way ANOVA. Results Higher degrees of fibrosis create smaller lesion volumes (M = mean volume ablation zone): M (0%) = 322 mm3 (SD 187 mm3), M (10%) = 226 mm3 (SD 94.8), M (20%) = 217 mm3 (SD 103 mm3) and M (50%) = 186 mm3 (SD 92.7 mm2). Lesion volumes in fibrotic tissue differ significantly from lesion volumes in fibrotic-free tissue (F(3,124) = 6.94, p<0.001). There is a significant difference in lesion volumes for all degrees of fibrosis compared to fibrosis-free tissue (MD = mean difference of ablation zone volumes between 0% fibrosis and 10, 20 and 50% fibrosis): MD (0, 10%) = 95.6 mm3 (95% confidence interval (20.8–170), p=0.008), MD (0, 20%) = 105 mm3 (95% confidence interval (30.4–180), p=0.003) and MD (0, 50%) = 135 mm3 (95% confidence interval (60.7–210), p<0.001). We also found a significant difference in lesion volumes related to the content of fiber in a comparison of all groups (F(3,120) = 7,49, p≪0.001). There is no significant difference in lesion volumes related to the used ablation mode (F(1,120) = 2.89, p=0.09). There is also no significant difference in lesion volumes related to the interaction between the content of fiber and the ablation mode (F(3,120) = 1.23, p=0.3). Conclusion Lesions created by RF ablation are influenced by fibrosis. A higher content of fibrosis is associated with smaller lesion volumes. Neither LPLD nor HPSD ablation mode shows an advantage in fibrotic tissue. Funding Acknowledgement Type of funding sources: None.