Angiographic and histological characterization of pulsed field ablation-induced coronary spasm: Differential effect of 2 waveforms

BACKGROUND: Pulsed field ablation (PFA) near coronary arteries has been associated with acute vasospasm, primarily linked to electric field intensity. However, the impact of other waveform characteristics, such as pulse number, has not been studied and could have physiopathological implications. OBJECTIVE: This study aimed to compare a clinically relevant full PFA waveform against a single-pulse configuration to evaluate differences in vasospasm incidence, severity, recovery kinetics, and associated histological changes. METHODS: 8 anesthetized pigs underwent epicardial PFA directly over the left anterior descending (LAD) artery using 2 protocols: a full waveform (2 kV, 450 pulses) and a single-pulse waveform (2 kV, 1 pulse). Coronary angiography was performed before, immediately after, and every 5 minutes until spasm recovery or 20 minutes. Animals were euthanized >2 hours post-ablation for histological analysis. RESULTS: 37 ablations were performed (23 full, 14 single-pulse). Acute vasospasm occurred in all cases (100%). Mean luminal stenosis was similar between groups (full vs single-pulse: 59 ± 10% vs 68 ± 10%, P = not significant). Lesion depth was greater with full pulses (7.5 ± 1.8 mm vs 3.4 ± 0.8 mm, P < .0001). Histology revealed comparable patterns of internal elastic lamina disruption across both groups. CONCLUSION: Coronary vasospasm, though highly dependent on electric field intensity, exhibited little sensitivity to pulse number, occurring even after a single pulse. This suggests that vasospasm is primarily triggered by field strength rather than by the cumulative energy parameters required for lesion formation. Furthermore, the observation of acute intimal injury suggests that the intima may play a central role in the pathophysiology of PFA-induced vasospasm.