Endocardial impedance mapping during circumferential pulmonary vein ablation of atrial fibrillation differentiates between atrial and venous tissue

Circumferential pulmonary vein ablation (CPVA) is an effective treatment for atrial fibrillation (AF). Accurate left atrial (LA) mapping is essential for creating lesions at the LA–pulmonary vein (PV) junction, avoiding PV stenosis. The purpose of this study was to establish whether endocardial impedance varies within the LA and PVs and whether it is a useful tool for mapping and ablation. Pilot Phase: Three-dimensional LA maps were created using CARTO. Impedance (Z) was measured using a radiofrequency generator at multiple points in the LA, PV ostia (PVO), and deep PVs in 79 patients undergoing their first AF ablation (group 1) and 29 patients undergoing repeat CPVA (group 2). Prospective Phase: In an additional 20 patients, using pilot phase data, one operator defined catheter tip location as either LA or PVO based on CARTO and fluoroscopy. A second operator blinded to CARTO simultaneously did the same based on impedance at 15 ± 4 points per patient. Group 1: Z LA was 99.4 ± 9.0 Ω. Z PVO was higher (109.2 ± 8.5 Ω), rising further as the catheter advanced into deep PV (137 Ω ± 18). Z PVO differed from Z LA by 9 ± 4 Ω. Group 2 had a lower Z LA and Z PVO compared with group 1 ( P