Abstract 9570: Adenosine Triphosphate Facilitates Dormant Conduction across Left Atrial Lines in Patients With Atrial Fibrillation Who Underwent Catheter Ablation

Introduction: The addition of left atrial lines including a roof line, bottom line, and mitral isthmus line after pulmonary vein (PV) isolation may lead to a favorable outcome of atrial fibrillation (AF) ablation. Transient reconduction of the isolated pulmonary vein (PV) is induced by administration of adenosine triphosphate (ATP) and elimination of dormant conduction improves outcome of AF ablation. The potential role of ATP in other arrhythmic substrates, such as left atrial lines, remains unclear. The aim of this study was to investigate the characteristics and frequency of dormant left atrial line conduction. Methods: Sixty-four patients (50 men; mean age 65±10; 3 paroxysmal, 26 persistent, 35 Longstanding persistent) who underwent first ablation of left atrial lines were enrolled in this study. A roof line, bottom line and mitral isthmus line were performed in 63 patients, 44 patients and 64 patients, respectively. Irrigated ablation catheters were used through steerable sheaths with a max power of 35W at the endocardial surface and 30W in the coronary sinus. ATP (20mg) was given greater than 10 minutes after completion of left atrial lines to reveal dormant conduction. Results: Completion of a roof line, bottom line and mitral isthmus line was achieved in 97% (61/63), 98% (43/44), and 95% (61/64), respectively. Following administration of ATP, dormant conduction was observed in 3.2% at a roof line, 2.3% at a bottom line, and 3.2% at a mitral isthmus line. Persistent reconduction was observed in 1.6% at a roof line and 2.3% at a bottom line. Transient reconduction was observed in 1.6% at a roof line and 3.2% at a mitral isthmus line. Following additional ablation, dormant left atrial line conduction was eliminated in all patients. The frequency of dormant left atrial line conduction was similar to that of dormant PV conduction (6.3% vs 7.8%., P=0.7) Conclusion: Administration of ATP could reveal dormant left atrial line conduction. Dormant conduction was evenly induced among PVs and left atrial lines.