Local modifications in tissular conditions before PFA increases acute lesion size

Pulsed field ablation (PFA) is a novel nonthermal cardiac ablation technology based on irreversible electroporation. Although calcium-enhanced electroporation to treat solid tumors has proved successful, the applicability of this technique to create deeper lesions in the left ventricle remains unknown.

This study aimed to determine whether changes in local tissular conditions may have an impact on lesion formation in PFA.

5 anesthetized pigs received local epicardial injections of 200 mM calcium chloride (CaCl₂) and PFA treatments. Local injections of phosphate-buffered saline (buffer) solution combined with PFA treatments and local injections of CaCl₂ without PFA treatments were also performed. Acute lesion formation was assessed after 2 hours by 2,3,5-triphenyltetrazolium chloride staining.

We performed 31 ablations (21 CaCl₂ + PFA, 10 buffer + PFA, 3 CaCl₂ alone). Histological staining of acute lesions revealed that the CaCl₂ + PFA lesions were larger than buffer + PFA lesions (width CaCl₂ + PFA vs buffer + PFA 5.9 ± 0.9 mm vs 4.3 ± 0.9 mm; P < .01). Injection of CaCl₂ alone did not produce any observable lesion. In 48% of CaCl₂ + PFA lesions, ventricular fibrillation was induced compared with 0% in buffer + PFA lesions.

In this proof-of-concept study, we show for the first time that changes in local tissular conditions may have an impact on lesion formation in PFA. The combination of calcium injection and PFA induced ventricular fibrillation in half of the applications.