Predictors of cerebral microembolization during phased radiofrequency ablation of atrial fibrillation: Analysis of biophysical parameters from the ablation generator

BACKGROUND: Pulmonary vein isolation with phased radiofrequency current and use of a pulmonary vein ablation catheter (PVAC) has recently been associated with a high incidence of clinically silent brain infarcts on diffusion-weighted magnetic resonance imaging and a high microembolic signal (MES) count detected by transcranial Doppler. OBJECTIVE: The purpose of this study was to investigate the potential correlation between different biophysical parameters of energy delivery (ED) and MES generation during PVAC ablation. METHODS: MES counts during consecutive PVAC ablations were recorded for each ED and time stamped for correlation with temperature, power, and impedance data from the GENius 14.4 generator. Additionally, catheter-tissue contact was characterized by the template deviation score, calculated by comparing the temperature curve with an ideal template representing good contact, and by the respiratory contact failure score, to quantify temperature variations indicative of intermittent contact due to respiration. RESULTS: A total of 834 EDs during 48 PVAC ablations were analyzed. A significant increase in MES count was associated with a lower average temperature, a temperature integral over 62°C, a higher average power, the total energy delivered, higher respiration and template deviation scores (P <.0001), and simultaneous ED to the most proximal and distal poles of the PVAC (P <.0001). CONCLUSION: MES generation during ablation is related to different indicators of poor electrode-tissue contact, the total power delivered, and the interaction between the most distal and the most proximal electrodes.