TPI Function in Pulsed Field Ablation for Atrial Fibrillation: Hemolysis Control and Organ Protection.

BACKGROUND: In pulsed field ablation (PFA), adequate catheter-tissue contact is crucial as it can effectively reduce the occurrence of hemolysis. Activation of the tissue proximity-indicating (TPI) function ensures effective catheter-tissue apposition. However, to date, no relevant clinical studies have been reported on the correlation between TPI function activation and hemolysis during PFA for atrial fibrillation (AF). OBJECTIVES: To investigate in depth the correlation between the "TPI" function of catheters and postoperative hemolysis following pulsed field ablation (PFA) for atrial fibrillation (AF) from hematological and pathological perspectives. METHODS: By applying PFA treatment in both TPI-ON and TPI-OFF modes to isolated porcine atrial myocardial tissue and in situ atrial myocardium from six pigs, the effects on hemolysis were observed under these two scenarios. RESULTS: In vitro, plasma free hemoglobin (fHb) increased with the number of applications and was lower with TPI-ON than with TPI-OFF at matched application numbers (p < 0.05). In vivo, both groups achieved transmural lesions with comparable lesion depth. Mean fHb values at 5 and 30 min were numerically lower with TPI-ON, but the group-by-time interaction was not significant (p = 0.153). CK and CK-MB increased transiently within 24 h, whereas urea and creatinine showed no consistent between-group pattern; none of the four biochemical group-by-time interactions remained significant after Holm correction. Renal histology showed no irreversible parenchymal injury in either group. CONCLUSION: In this preclinical model, use of the impedance-based TPI function was associated with lower post-PFA hemolysis while preserving acute transmural lesion formation. These findings support further validation of TPI-guided catheter positioning in clinical studies.