Post ablation mapping and inducibility of atrial tachycardia in different pulsed field ablation technologies

Pulsed field ablation (PFA) is a rapidly developing non-thermal ablation method leading to irreversible electroporation by application of short electrical pulses. Several PFA catheters with different designs, voltage output and energy delivery have been developed (1), therefore lesion durability and size may differ between the systems. This study was designed to compare lesion sizes and to evaluate if large posterior wall lesions leading to small interlesion distances are associated with roof dependent flutter inducibility and occurrence at follow up.

Consecutive patients who presented for atrial fibrillation ablation with PFA using three different ablation technologies were included. All patients underwent high density post ablation mapping. Peak-to-peak electrogram bipolar amplitude < 0.5 mV was defined as low-voltage area threshold (Varipulse and PulseSelect; 5); for Affera cases, unipolar low-voltage maps were created with a cutoff of 0.05 mV.

Interlesion distance was measured

a) at the left atrial roof

b) at the posterior wall at the minimal distance between the PV lesions and at the

c) lower margin of the PV ablation lesion.

In a subset of patients, atrial stimulation until the atrial refractory period was performed after PV ablation. Follow up was scheduled at 3, 6 and 12 months.

69 patients were included. Baseline characteristics showed no significant differences between the three groups (see table 1). PV isolation was achieved in all cases. Interlesion distances differed significantly between PFA systems (see table 2). Burst stimulation in 37 patients did not induce sustained atrial tachycardia. After a mean follow-up of three months, one patient experienced sustained atrial tachycardia (perimitral flutter).

To our knowledge, this study is the first to comparatively assess interlesion distances between three current PFA ablation systems. The study shows considerable variability in lesion size and therefore interlesion distance. So far there is no sign for an increased number of roof dependent flutter episodes during follow up.