Local coronary flow alterations induced by pulsed field ablation without detectable ECG changes
A Borachok, G Amoros-Figueras, Q Castellvi, S Casabella-Ramon, M Soriano-Amores, A Ivorra, J GuerraAbstract
Background/Introduction
Pulsed field ablation (PFA) is an emerging therapy for cardiac arrhythmias that creates non-conductive lesions through irreversible electroporation while sparing adjacent structures. When delivered near to coronary arteries, PFA can induce transient coronary vasospasm [1], but its haemodynamic and electrocardiographic impact remains poorly characterised.
Purpose
To evaluate coronary flow and ECG changes associated with PFA-induced vasospasm at different distances from the application site.
Methods
Four domestic swine (59 ± 6 kg) underwent thoracotomy and pericardial suspension under general anaesthesia, as described in [2]. A coronary flow probe was placed on the distal left anterior descending (LAD) coronary artery for continuous blood flow measurement (Figure 1A), and surface ECG was continuously recorded. PFA (450 kHz, Vpp = 2 kV) was delivered at epicardial sites over the LAD. Flow recordings and ECG data were analysed prior to ablation ("pre-PFA") and immediately afterwards, during the vasospasm ("post-PFA"). Applications were classified as "near" (≤ 1 cm) or "far" (> 1 cm) depending on their distance from the measurement point (Figure 1B). For ECG analysis, 30-60 s of signal were selected before and after each PFA. Cardiac cycles within each segment were superimposed and averaged to detect subtle electrical differences between pre- and post-PFA.
Results
Vasospasm occurred in all LAD-targeted PFA applications. "Near" sites showed a significant increase in local flow velocity (pre vs. post: 15.5 ± 4.6 mL/min vs. 28.3 ± 2.6 mL/min; p < 0.05), consistent with transient luminal narrowing and resulting flow acceleration as predicted by fluid dynamics (Figure 1C) [3]. "Far" sites exhibited no significant change (pre vs. post: 14.5 ± 5.9 mL/min vs. 15.4 ± 4.7 mL/min; p = ns). ECG averaging analysis revealed no detectable electrical changes post-PFA (Figure 2).
Conclusions
PFA-induced vasospasm of the LAD transiently alters local coronary flow without affecting surface ECG. These changes are confined to the immediate vicinity of the vasospasm and dissipate with distance, preserving distal baseline perfusion. These findings suggest that vasospasm in the clinical setting may not necessarily be associated with ECG changes. Further studies in smaller coronary branches are warranted to assess compensatory capacity in vessels with more limited flow reserve.Figure 1.Blood flow measurementsFigure 2.Averaged surface ECG waveforms