Backgrounds: Catheter ablation of recurrent atrial tachyarrhythmia after Maze operation is challenging due to complex arrhythmia circuits. The aim of this study was to clarify the characteristics and ablation outcomes of atrial tachyarrhythmias after Maze operation. Methods and Results: Twenty-eight cases who underwent catheter ablation of post-Maze procedure atrial tachyarrhythmia (42 sessions; 1.5 per patient) in our 5 teaching affiliate hospitals were retrospectively analyzed. Cox-Ⅳ Maze procedure and left atrial Maze were performed in 19 cases and 5 cases, respectively. Mean interval between the surgery and index ablation was 62.4 months. In total, 46 atrial tachyarrhythmias were studied. Reentrant atrial tachycardia (AT) was the most common form (n=36), whereas 4 atrial fibrillation (AF) and 2 focal AT were also observed. Identified tachyarrhythmia circuits were as follows; 16 peri-mitral, 9 left atrial localized reentry (4 septal, 3 posterior, 1 left atrial appendage, 1 anterior), 6 right atrial lateral incision-related, 5 cavo-tricuspid isthmus dependent, 3 roof dependent, 2 right atrial localized reentry (1 coronary sinus, 1 cavo-tricuspid isthmus), 1 bi-atrial reentry, 1 pulmonary vein-left atrial reentrant tachycardia, 2 focal AT (1 para-hisian, 1 coronary sinus), and 1 atrio-ventricular nodal reentry. Termination of targeted tachyarrhythmia was achieved in 34 sessions (81%). AT/AF recurrence free rate at 12, 24, 36 months of follow-up were 91.8%, 81.6%, and 65.3%, respectively. Seven cases underwent multiple sessions (two 2 nd sessions, three 3 rd sessions, and two 4 th sessions). In these cases, de-novo atrial tachyarrhythmias were detected in the repeat procedures. Conclusions: Most of the atrial tachyarrhythmias after Maze operation were incision/gap-related reentrant ATs, among which peri-mitral AT and LA localized reentry were the most prevalent. Although these challenging tachyarrhythmias can be treated with the contemporary mapping techniques, de-novo tachyarrhythmias can emerge in a remote period.

Background and Objective: Ectopic beats originating from the pulmonary vein (PV) trigger atrial fibrillation (AF). The purpose of this study was to clarify the electrophysiological determinant of AF initiation from the PVs. Methods: Pacing studies were performed with a single extra stimulus mimicking an ectopic beat in the left superior pulmonary veins (LSPVs) in 62 patients undergoing AF ablation. Inducibility of AF, effective refractory period (ERP) and conduction properties within the PVs were analyzed. Results: A single extra stimulus in LSPV induced AF in 20 patients (32% of all patients) at the mean coupling interval (CI) of 172 ms. A CI-dependent anisotropic conduction at the AF onset was visualized in a 3D-mapping. Onset of AF was site-specific with reproducibility in each individual. Mean ERP in LSPV in the AF inducible group was shorter than that in the AF non-inducible group (182 ± 55 ms vs 254 ± 51 ms, P<0.0001). LSPV ERP dispersion was greater in the AF inducible group than in the AF non-inducible group (45 ± 28 ms vs 27 ± 19 ms, P<0.01). Circumferential intra-PV conduction time (IPVCT) exhibited decremental properties in response to shortening of CI, and the prolongation of IPVCT in the AF inducible site was greater than that in the AF non-inducible site (P<0.05) in each individual. Conclusions: Location and coupling interval of an ectopic excitation ultimately determine the initiation of AF from the PVs. ERP dispersion and circumferential conduction delay may lead to anisotropic conduction and reentry within the PVs that initiate AF.