Does the Number of Simultaneously Activated Electrodes During Phased RF Multielectrode Ablation of Atrial Fibrillation Influence the Incidence of Silent Cerebral Microembolism?

Background: Asymptomatic cerebral embolus (ACE) detected by diffusion-weighted magnetic resonance imaging (DW-MRI) following atrial fibrillation (AF) ablation has been reported at varying rates with different ablation techniques.

Objective: To evaluate the incidence of ACE after phased radiofrequency ablation for AF with procedural modifications that potentially reduce the embolic load.

Methods: One hundred twenty consecutive patients with AF underwent MRI before ablation, 24 hours after ablation, and at 4-6 weeks. In all patients, simultaneous activation of pulmonary vein ablation catheter electrode pairs 1 and 5 was forbidden. While in 60 group 1 patients, a maximum of 4 electrode pairs could be activated at a time, and in 60 group 2 patients, ablation was limited to a maximum of 2 pairs. All patients were on uninterrupted phenprocoumon, with an attempted activated clotting time of >300 seconds during ablation.

Results: Both patient groups were comparable. A total of 28 DW-positive lesions were detected in 24 of 120 patients (20%). Seventeen group 1 patients (28.3%) were positive for new asymptomatic DW cerebral lesions compared with 7 group 2 patients (11.7%) (P = .039). During MRI follow-up, 3 patients (2.5%) were diagnosed with a small T2-positive asymptomatic glial scar. Procedure time was longer in group 2 patients than in group 1 patients (159 ± 39 vs 121 ± 15; P < .001).

Conclusions: Limiting the number of simultaneously activated electrode pairs to 2 significantly reduces the rate of ACE in patients treated with a multielectrode duty-cycled phased radiofrequency catheter system for AF. This reduction corresponds with a significant prolongation of the total procedure time.