Esophageal heating characteristics of very high-power short duration radiofrequency ablation in a myocardial phantom model

Background: Very high short duration radiofrequency catheter ablation can rapidly achieve pulmonary vein isolation, however safety to the esophagus during posterior left atrial ablation is uncertain. This study looked to characterise lesion formation and esophageal thermal effects with very high-power short duration (vHPSD), and to compare it with high power short duration (HPSD) and low power long duration (LPLD) radiofrequency ablation, using esophageal heating and esophageal temperature probe (ETP) measurements. Methods: A thermochromic gel phantom model of posterior left atrial wall with an embedded ETP was used to assess heating kinetics during radiofrequency ablation (RFA). RFA was performed at 30W/20s (LPLD), 50W/5s (HPSD), 90W/3 and 90W/4s (vHPSD). Continuous ETP temperature was recorded, and thermal mapping of esophageal temperature was performed. Results: 90W/3s (5.17±0.01 mm) and 90W/4s (5.62±0.06 mm) produced broader lesions than 50W/5s (4.17± 0.11 mm, p<0.0001) and 30W/20 s (3.95±0.38 mm, p<0.01), with similar depth. The ETP underestimated the peak esophageal temperature across all ablation settings with the highest temperature disparity in 30W/20s (3.70±0.60°C, p=0.0007), 90W/3s (2.87±0.06°C, p<0.0001) and 90W/4s (2.53±0.25°C, p=0.0016) groups. Thermal latency was greatest in 90W/4s, followed by 90W/3s, 50W/5s and 30W/20s. Consecutive applications of RFA energy led to heat accumulation and greater esophageal heating, most marked with 90W/4s (41.13±0.12°C), and 30W/20s (40.90±0.10°C). Conclusion. vHPSD produces broader lesions with comparable depth which may result in improved PVI lesion contiguity, however, repeated successive applications with vHPSD may lead to greater esophageal heating and inaccurate ETP monitoring due to temperature disparities and thermal latency.