Cerebral microembolic signal burden during pulsed field ablation: Preliminary results from robotically-assisted transcranial doppler and magnetic resonance imaging

Background: Transcranial Doppler (TCD) has been used to monitor the burden of cerebral microembolic signals (MESs) during atrial fibrillation (AF) ablation. MES burden is considered a surrogate marker for stroke risk and has never been reported during AF ablation with pulsed field ablation (PFA). Purpose: To assess the MES burden during AF ablation with point-by-point radiofrequency (RF) versus single-shot PFA. Methods: Fifteen consecutive paroxysmal and persistent AF patients underwent catheter ablation via either single-shot (2000V) PFA [n=7, median age: 56yo (range:53-73), 85.7% males] or point-by point (45W) RF [n=8, median age: 58yo (range 56-74), 62.6% males] under uninterrupted oral anticoagulation and a periprocedural ACT≥300s. Peri-procedural TCD was performed via a robotically-assisted ultrasound system, which includes an artificial Intelligence-powered robotic headset designed to automate signal acquisition and reduce interoperator variability of TCD findings (Figure 1). Ablation-related asymptomatic cerebral embolism (CE) was assessed via diffusion-weighted imaging (DWI) sequences at magnetic resonance imaging (MRI) performed 24-48h post-ablation. Results: Among the 7 PFA patients, the median number of applications to achieve PV isolation was 35 (range:33-42). Five (71.4%) patients showed multiple MESs clustered in a shower-like pattern (Figure 2). The overall number of MES-showers was 51 [median: 9 (range:8-15)] and they were temporally correlated with a PFA application. Shower formation was more common after a PFA application to the right superior pulmonary vein [(PV); 19 cases (37.3%)], followed by the right inferior PV [16 cases (31.4%)], the left inferior PV [14 cases (27.5%)], and the left superior PV [2 cases (3.9%)]. A single shower-like pattern was documented among the 8 RF patients, following a stem-pop while ablating at the right inferior PV antrum. There were no procedure-related complications and none of the 15 patients showed any post-ablation neurological symptoms. The mean time from ablation to MRI was 29±4hours; DWI imaging revealed no acute cerebral microembolic lesions. Conclusion: PFA generated a relevant number of MESs frequently clustered in short-lasting shower-like patterns. The composition of MESs, their exact mechanism of formation, and the impact on neurological outcomes are unknown and will be addressed in future studies.