Abstract 3506: Electrophysiological Features of Atrial Tachyarrhythmia after Left Atrial Roof Line during Catheter Ablation of Atrial Fibrillation
Backgrounds; Several reports have suggested that the atrial tachyarrhythmia (AT) after catheter ablation for atrial fibrillation (AF) is generally caused by focally driven reentrant arrhythmia around the catheter modified pulmonary vein (PV). Left atrial roof line (LARL) could be associated with the increased incidence of following AT. We aimed to study the pathogenesis of AT after LARL.
Methods; Consecutive 98 patients with AF underwent catheter ablation were enrolled in this study (mean age; 61, Male; 67, chronic; 29, structural heart disease; AF period 58 months). All antiarrhythmic drugs were discontinued for at least 5 half-lives before the study. Atrial tachyarrhythmia was induced by intensive burst pacing (up to 150 ms from at least 3 sites including coronary sinus and right atrium) under isoproterenol infusion (1–2 mcg / min) after the electrical isolation of PVs. In cases of AF induced by pacing and/or of chronic AF, LARL was additionally created, and then the same induction protocol was conducted again. Electrical circuit course was estimated from pacing return cycle length.
Results; LARL was required to prevent AF perpetuation in 65 patients (68%). Electrical conduction block at PV ostia was successfully created in 63 of 65 patients (97%). Although burst pacing could induce AF in 58 patients (59%) and roof dependent AT in 9 (9%) was induced before LARL, and AF was induced in 28 of 65 patients (43%) after LARL. 112 AT episodes (92 stable and 20 unstable circuits) were observed after LARL. The estimated circuits were successfully determined in 79 of 92 stable AT (87%), including tricuspid ishmus (35%), mitral ishmus (14%), septum (10%), right pulmonary veins (9%), coronary sinus ostium (5%), left pulmonary veins (3%) and superior vena cava (2%). Endocardial catheter ablation (CA) successfully terminated 80 (87%) of 92 stable AT. If the mitral ishmus was involved, radiofrequency application from endocardial site terminated AT in 5 of 14 patients (38%).
Conclusion; 1) LARL facilitates to prevent the perpetuation of AF; but re-entrant AT could be highly induced. 2) Scar boundary after LARL and preexistent electrical conduction abnormalities is likely to allow the increased macro reentrant AT away from PV.