Identification of conduction gaps in the ablation line during left atrium circumferential ablation:: Facilitation of pulmonary vein disconnection after endpoint modification according to electrogram characteristics

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 etectrogram amplitude or 0.1 mV). Phase 11: 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.