Assessment of acute EIVM effect by EAM
LA bipolar voltage mapping was performed before and immediately after EIVM by using the duodecapolar PentaRay catheter and the CARTO3 v6 or v7 EAM system (Johnson & Johnson, Irvine, CA) with the Tissue Index Proximity tool activated to ensure tissue contact for each recorded electrogram. The rhythms during which voltage mapping was performed was SR, AF or PLMAF before EIVM and SR, AF or PLMAF after EIVM. For patients in whom EIVM acutely changed the atrial rhythm (n=8 [29%], including AF to PMLAF, n=4; PMLAF to sinus rhythm, n=3; PMLAF to roof-dependent flutter, n=1), we performed no specific correction to take into account the correlation of electrogram amplitude to the type of atrial rhythm. The scar area in the VOM region was defined as the area with bipolar voltage <0.05 mV. The PV was excluded from scar area analyses because PV volume acquisition may vary substantially between procedures. The scar area was delineated by using the “Area Measurement” tool of the CARTO3 software. Scar areas in the VOM region before and immediately after EIVM were compared to assess the acute EIVM effect (Figure 1).