Electroanatomic remodeling of the left atrium in patients undergoing repeat pulmonary vein ablation: mechanistic insights and implications for ablation.

INTRODUCTION: There is limited information describing late changes in the electroanatomic characteristics of the left atrium (LA) associated with recurrence after an anatomical circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF).

METHODS AND RESULTS: Forty-seven patients (57 +/- 8 years) undergoing a repeat ablation after CPVA were included. Using an electroanatomic mapping system, we measured the bipolar voltage by averaging points in the pulmonary vein (PV)-LA junction and four other LA sites. Conduction velocity and AF cycle length (AFCL) were also measured and the results are compared with the first procedure. After an initial decrease observed at the end of the first procedure, voltage and conduction velocity returned to intermediate values in all LA sites, with lower voltage at the LIPV antrum (P = 0.004), and lower conduction velocity across the LIPV and RSPV (P < 0.001). Conduction gaps were more prevalent at the septal aspect of the right PV encircling lines (85%), between the left atrial appendage (LAA) and the LSPV (70%) and lines at the posterior wall (71%). There was a nonsignificant increase in AFCL, with a more widespread distribution of organized electrograms (32.4% vs 46.6%).

CONCLUSION: Recurrence after CPVA is associated with a reverse process of voltage and conduction velocity increase across ablated areas, especially the PV-LA junction, and is related to the presence of conduction gaps, which are distributed mostly at the septal aspect of the lines encircling the right PVs and at the LAA-LSPV area. Organization of atrial electrograms seen during AF ablation is maintained at a repeat procedure.