Parallel Study on Surface and Invasive Recordings Across Catheter Ablation Steps of Paroxysmal Atrial Fibrillation

Catheter ablation (CA) is the star treatment of atrial fibrillation (AF). However, important issues regarding its procedure have only been superficially explored. While universal CA effect is assessed, the role of right (RPVI) and left pulmonary vein isolation (LPVI) is ignored. Although coronary sinus (CS) is the prevailing CA reference, how CS itself is modified by CA is unknown. This work evaluates the effect of each ablation step on the atrial substrate and CS funtion. Five-minute lead II and bipolar CS recordings of 29 patients undergoing paroxysmal AF CA were acquired before CA, after LPVI and after RPVI (end of CA). Separate lead II and CS analysis was performed. Duration, amplitude, area and slope rate were calculated for each surface and invasive activation, then signal-averaged. Dispersion, morphology variability (MV) and time-domain heart-rate variability (HRV) features were also calculated. Non-parametric tests were recruited to compare each feature among all and in pairs of different ablation steps with Bonferroni correction. Variation of each feature was calculated in percentages. In surface recordings, duration was significantly shortened after LPVI (Delta = -13%, p = 0.001) and HRV showed a trend for attenuation (Delta < -25%, p < 0.069) after RPVI. In CS recordings, HRV showed an increasing trend after LPVI (Delta > +73%, p < 0.048), tending to decrease after RPVI (Delta <-33%, p < 0.064). Higher dispersion in variations was observed in CS than surface recordings. LPVI causes major alterations in atrial substrate, more prominently observed from lead II analysis. Notwithstanding, HRV variations are better illustrated in CS recordings. A combined analysis of both is recommended.