Po-04-133 impact of a close indifferent electrode on atrial unipolar and bipolar electrograms

Although intracardiac unipolar electrograms (egms) are frequently recorded using Wilson Central Terminal (WCT) as a reference, this may sometimes result in a mis-annotation due to larger noises. A novel multielectrode mapping catheter (OptrellTM, Biosense Webster, CA), equipped with a close indifferent electrode embedded in the catheter shaft (TRUErefTM technology), may improve the quality of egms. We systemically compared the amplitude and morphology of the unipolar- and bipolar- egms between WCT-based egms and TRUErefTM-based egms. Patients undergoing catheter ablation were studied. Right atrium was mapped under sinus rhythm, using the OptrellTM catheter catheter. The catheter was sequentially placed on the myocardial surface to record intracardiac signals, and each site was mapped with the two configurations (WCT-based and TRUErefTM-based) before moving the catheter to another site. In seventeen patients (mean age 60±17 years, 82% male) studied, right atrial mapping was undertaken during sinus rhythm. Median number of points acquired per patient were, 1277 [1052-1481] and 1347 [1183-1556] for maps using TRUErefTM and WCT, respectively. A total of 19948 for TRUErefTM and 20911 points for WCT were analyzed. Unipolar egm amplitude, bipolar egm amplitude and dV/dt acquired using TRUErefTMwere all significantly larger than those recorded with WCT (2.45 [1.50-3.86] vs 2.07 [1.32-3.21], p<0.0001; 1.60[0.96-2.96] vs 1.53 [0.66-2.92], p<0.0001; 0.42 [0.20-0.80] vs 0.39 [0.17-0.76], p<0.0001, respectively, see Figure). When each patient was analyzed individually, unipolar egm amplitude recorded using TRUErefTM was significantly larger than those acquired with WCT in 14 out of 17 patients (82%), and comparable in three (18%). Median bipolar egm amplitude recorded using TRUErefTM was significantly larger than those acquired with WCT in three patients (18%), and comparable in 14 (82%). Median dV/dt recorded using TRUErefTM was significantly larger than those acquired with WCT in three patients (18%), comparable in 13 (76%), and smaller in one (6%). Unipolar recording using a close indifferent electrode significantly affects egm characteristics. Our result may be of relevance when intracardiac mapping is performed using TRUErefTM technology.