Abstract 2438: Local Bipolar Atrial Electrogram Monitoring during the Extensive Encircling Pulmonary Vein Isolation: Implications of the ``QS Pattern” in the Local Bipolar Atrial Electrogram after the Ablation
BACKGROUND During the extensive encircling pulmonary vein (PV) isolation (EEPVI) for atrial fibrillation (AF), it is crucial to recognize whether or not a sufficient lesion was created by an ablation in each ablation site. The local electrogram (EG)-based criteria to predict a sufficient local lesion formation, however, remain to be established. This study was performed to define local EG-based criteria for the local lesion formation during the EEPVI for AF.
METHODS Among 31 patients (pts) with AF who had successful EEPVI during coronary sinus pacing, bipolar local EGs at 2271 ablation sites (73+/-19 sites/pt, posterior wall (PW) of the left atrium (LA)/anterior LA-PV junction=976/1295 sites) before and after energy delivery were reviewed. In EEPVI, ipsilateral PVs, antral regions and parts of the PW of the LA were isolated as a whole by linear ablation at the PW of the LA and semi-linear ablation at the anterior LA-PV junction. Each energy application was performed with a temperature controlled mode (maximal temperature: 55 degrees Celsius, maximal output: 35 watt) and duration of 25 to 35 seconds.
RESULTS After the ablation, all PVs, antral regions and parts of the PW of the LA were successfully isolated in all 31 pts (duration of each energy application: 31+/-3 sec/site, total energy application time: 37+/-10 min/pt). After the effective ablation at each site, the local EGs exhibited predominant reduction in the amplitude of positive deflection (Ap) as compared to that of negative deflection (An) (% reduction in Ap vs An: 91+/-10 vs 30+/-59%; p<0.01, Ap/An ratio before vs after ablation: 2.3+/-3.4 vs 0.3+/-0.1; p<0.01) as well as total amplitude reduction (67+/-22%) and EG widening (57+/-43%), and the morphology of the local EG changed to the ``QS” or ``rS” patterns. At 25 sites without those morphological changes, residual LA-PV conduction gaps were observed and additional ablations were required to achieve a complete EEPVI in 20 pts.
CONCLUSION We propose that a morphological change of local EGs to ``QS” or ``rS” patterns with predominant attenuation of positive deflection of local EGs can reflect sufficient local lesion formation and can be one of the practical endpoints for energy delivery at each ablation site during the EEPVI.