Background: Left atrium circumferential ablation (LACA) is a simple, effective treatment for atrial fibrillation (AF), but many pulmonary veins (PV) are not disconnected because of conduction gaps (CG) in the ablation line.
Objective: This study defined the electrogram characteristics at the CGs and at the PV- left atrium (LA) connection site and assessed the effect of modifying ablation endpoints at these sites.
Methods: Forty consecutive patients underwent LACA. Phase I: In 15 patients, electrogram characteristics at the LA-PV connection, CGs at the ablation line, and PV disconnection rate were evaluated during LACA with current ablation endpoints (80% reduction in electrogram amplitude or 0.1 mV). Phase II: 25 patients underwent LACA with modified endpoints according to the results of Phase I.
Results: Phase I: Fifty-five PVs were analyzed, 17 during sinus rhythm (SR) and 38 during AF. LA-PV connections were characterized by multicomponent electrograms (ME) without an isoelectric line (0.45 +/- 0.43 mV, 77 +/- 21 ms). After LACA, 55% of PVs were disconnected. In 85% of nondisconnected veins, ME (0.11 +/- 0.02 mV) were recorded at CGs where ablation caused PV disconnection. Phase II: Ninety-five PVs, 52 during AF and 43 during SR underwent LACA with modified ablation endpoints at ME sites: Disappearance of late component and voltage reduction to <0.05 mV. Eighty-five per cent of PV were disconnected (95% in SR and 77 % in AF, P <.01).
Conclusion: MEs identify LA-PV connections and CGs. Modification of ablation endpoints at these sites should facilitate PV disconnection during LACA.