Mitsuru Takami, Kimitake Imamura, Hidehiro Iwai, Mitsuhiko Shoda, Atsushi Murakami, Shogo Yonehara, Mari Yamamoto, Hiroyuki Asada, Takahiro Kunigita, Ryosuke Takahashi, Wako Suehiro, Takafumi Tsuboi, Takahito Nakano, Koji Fukuzawa, Hiromasa Otake
BACKGROUND: Although pulsed field ablation (PFA) is generally considered safe, the mechanisms underlying both symptomatic and silent embolic events remain unclear. OBJECTIVES: This study aimed to investigate the timing, number, size, and characteristics of microembolic signals (MESs) during each step of the pentaspline PFA procedure using real-time carotid Doppler monitoring. METHODS: MESs were assessed during ablation procedures in 32 patients, including 27 who underwent pulmonary vein (PV) isolation with the pentaspline PFA system and 5 control patients who received radiofrequency ablation limited to the right atrium. RESULTS: The PFA group showed significantly more MESs than the control group. MESs were detected throughout the PFA procedure, with the highest counts observed during PFA delivery to the right PVs. Bubble signals were seen in all procedural steps. In contrast, high-intensity transient signals, which are mainly composed of solid components, were more common during PFA energy delivery. All 303 overcurrent errors-events in which energy delivery is stopped owing to overcurrent detection-occurred during basket-type PFA applications and were associated with a marked increase in MESs. Basket-configuration energy delivery resulted in a significantly higher number of MESs than the flower configuration, particularly in the right PVs. The size of MESs was significantly larger during PFA energy delivery than during catheter or sheath manipulation. CONCLUSIONS: This study demonstrated the characteristic timing, frequency, and morphology of MESs during pentaspline PFA procedures, providing insights that may help reduce embolic risks in future practice.