P-wave Measurements and Electrical Reconnection of the Posterior Left Atrium after Catheter Ablation for Atrial Fibrillation

Background: Recurrent atrial arrhythmias (RAAs) following posterior left atrial isolation (PLAI) for atrial fibrillation are common and are associated with reconnection of the PLA and pulmonary veins. We aimed to show that P-wave duration (PWD) and P-wave area under the curve (PWAUC) changes in patients undergoing PLAI can be measured using signal-averaged electrocardiogram (SAECG), and that reversal of these changes in patients with RAAs can be used to noninvasively detect reconnection. Methods: SAECG recordings before and after PLAI in 52 patients were analyzed for changes in PWD and PWAUC and also in 26 of these patients who had a repeat procedure for RAA. Results: PWD and PWAUC reduced significantly in most leads following PLAI (mean 104 ± 11 ms to 93 ± 15 ms [P < 0.001] and 3.53 ± 1.23 microvolt seconds (μVs) to 2.87 ± 1.23 μVs [P = 0.001], respectively). Reconnection was observed in 20 of 26 patients at the repeat procedure. Compared to after the first procedure, reconnected patients had increased PWD and PWAUC (e.g., the increase in V4 was 14.1 ± 20.9 ms [P = 0.01] and 0.98 ± 1.17 μVs [P = 003], respectively) at the repeat procedure, while nonreconnected patients had decreased PWD and PWAUC (in V4, it was decreased by 11.5 ± 7.0 ms [P = 0.05] and 0.97 ± 0.33 μVs [P = 0.001]). A change in lead V4 PWAUC > −0.29 μVs for detecting reconnection had a sensitivity of 94% and specificity of 100% (receiver operator characteristic area under the curve 0.97, P = 0.005). Conclusions: PLAI reduces PWD and PWAUC while reconnection increases them both. SAECG may be able to detect reconnection of the PLA noninvasively. (PACE 2010; 1324–1334)