The occurrence rate of atypical atrial flutter may be higher after pulsed field ablation compared to cryoballoon ablation

Background

Pulsed field ablation (PFA) has emerged as a non-inferior single shot ablation modality compared to thermal modalities. Based on our previous work, where we showed that the rate of fibroblast activation seems to be more pronounced after pulmonary vein isolation (PVI) with cryoballoon ablation (CBA) compared to PFA, we hypothesized that the rate of occurrence of atypical atrial flutter might be higher after PFA due to less pronounced/ nonhomogeneous lesion formation.

Methods

Baseline and periprocedural ablation data of 300 patients (n=200 PFA, n=100 CBA) having undergone 1^st-do PVI in two German centers for either paroxysmal or persistent atrial fibrillation (AF) were analyzed. Primary endpoint of our study was to observe the rate of atypical flutter or atrial tachycardia after PVI with PFA vs. CBA. Secondary endpoint was to observe the rate of AF recurrence after PFA compared to CBA. The events were censored after 500 days of follow-up (FU).

Results

The study included predominantly male patients with mean age of 66 years. The baseline characteristics were well balanced within the groups as well as the history of prior cardiac surgery (7.5% vs 4.0%, p=0.7; Table 1). More of the patients treated with CBA tended to have longer history of AF without reaching the level of significance (38.6 vs. 30.4 months, p=0.1). The procedural characteristics in respect to radiation time and procedure time were balanced within the groups, while the radiation dose was significantly higher in CBA group (1412.5 µGym²vs. 723 µGym², p<0.001). Median FU was 319 days. Atypical atrial flutter after PVI with PFA occurred significantly more often than after PVI with CBA (9.5% vs 4%, p=0.04) (Figure 1), while AF recurrence was similar after PVI with CBA vs. PFA (17.5% vs. 22.0%, p=1.0) (Figure 2).

Conclusion

Our study shows that within 500 days of follow up the rate of atypical atrial flutter after PVI with PFA is significantly higher than after CBA, possibly suggesting nonhomogeneous ablation lesion formation with current PFA-devices. The recurrence of AF was similar between the groups within 500 days of FU. Longer FU and larger patient cohorts with 3-D Mapping are needed to observe if this difference persists and if the individual mechanism of atrial flutter is different in PFA due to different method of cell death.

Table 1. Baseline and Procedural Characteristics

PFA, pulse field ablation; CBA, cryoballoon ablation; AF, atrial fibrillation, LVEF, left ventricular ejection fraction; LA, left atrium; BMI, body mass index, CAD, coronary heart disease; PVI, pulmonary vein isolation; AAD, antiarrhythmic drugs;