Visualization of fibroblast activation using Ga-FAPI PET/CT after pulmonary vein isolation with pulsed field compared with cryoballoon ablation.

BACKGROUND

Pulsed-field ablation (PFA) is a novel ablation modality for atrial fibrillation (AF) ablating myocardium by electroporation without tissue-heating. With its different mechanism of tissue ablation, it is assumed that lesion creation is divergent to thermal energy sources. Ga-fibroblast-activation protein inhibitor (FAPI) PET/CT targets FAP-alpha expressed by activated fibroblasts. We aimed to assess Ga-FAPI uptake in pulmonary veins as surrogate for ablation damage after PFA and cryoballoon ablation (CBA).

METHODS

26 patients (15 PFA, 11 CBA) underwent Ga-FAPI-PET/CT after ablation. Standardized uptake values (SUV) and fibroblast-activation volumes of localized tracer uptake were assessed.

RESULTS

Patient characteristics were comparable between groups. In PFA, focal FAPI uptake was only observed in 3/15 (20%) patients, whereas in the CBA cohort, 10/11 (90.9%) patients showed atrial visual uptake. We observed lower values of SUV (2.85 ± 0.56 vs 4.71 ± 2.06, P = 0.025) and FAV (1.13 ± 0.84 cm vs 3.91 ± 2.74 cm, P = 0.014) along with a trend towards lower SUV and SUV in PFA vs CBA patients, respectively.

CONCLUSION

Tissue response with respect to fibroblast activation seems to be less pronounced in PFA compared to established thermal ablation systems. This functional assessment might contribute to a better understanding of lesion formation in thermal and PFA ablation potentially contributing to better safety outcomes.