Comparison of cerebral micro-embolization detected by transcranial doppler examination between radiofrequency ablation and pulsed field ablation for atrial fibrillation

Introduction:
Cerebral ischemia is a rare but severe complication after catheter ablation (CA) of atrial fibrillation. Pulsed Field Ablation (PFA) is a promising alternative nonthermal ablation method establishing pulmonary vein isolation via irreversible electroporation and is believed to reduce overall complications. The incidence of ischemic lesions on cerebral MRI after PFA has been described as low as 3%, but data on real-time assessment of microembolic signals (MES) measured by transcranial doppler (TCD) are lacking. Therefore, we sought to compare the incidence of MES assessed by TCD during different procedural steps between PFA and radiofrequency ablation (RFA).

Methods:
Consecutive patients who met the following inclusion criteria were prospectively recruited at the DHZC, Campus Benjamin Franklin, between 2022 and 2024: (a) first-time CA of paroxysmal or persistent atrial fibrillation (b) no anticipated additional left atrial ablation.
TCD was performed using a DWL Multi-Dop T2 system (DWL Elektronische Systeme GmbH) and one pulsed-wave 2-MHz Doppler probe fixed to the patient’s head with the DiaMon (DWL) system. To exclude artifacts, each detected MES was manually controlled by a neurologist after the procedure was completed.
MES were assigned to the following steps: (1) transseptal puncture, (2) introduction of catheters (3) electroanatomical mapping, (4) ablation and (5) removal of the catheters.
All patients gave written informed consent and underwent continuous TCD examination during CA.

Results:
In total, 34 patients were analyzed and 26 patients were included for statistical analysis (see figure 1). CA was successfully performed with single transseptal puncture in all patients. More patients with PFA were ablated under continued oral anticoagulation, requiring significantly less heparin administration (see table 1). However, the ACT (activated clotting time) was similar between the two groups. PFA had significantly higher MES-counts, especially during ablation, compared to RFA.
Two complications occurred in the PFA group (one postinterventional ischemic stroke and one transient phrenic nerve palsy) while no complication was seen in the RFA group (p=0.065). In the patient with ischemic stroke, the MES-count was not elevated above average (n=319 in total, see table 2).


Conclusion:
MES-count varies significantly between RFA and PFA, indicating a higher risk for cerebral lesions in PFA. Further patients will be recruited and pre- and postprocedural MRI will be performed for additional evidence.

Table 1: Ablation and procedural characteristics