Mechanism and outcomes of atrial tachycardia ablation in patients with mitral valve surgery

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardia (AT) is a common rhythm disorder after mitral valve surgery which may comprise both atria. Most of atrial arrhythmias are refractory to antiarrhythmic drugs and catheter ablation is usually required in cases with mitral valvular prosthesis. Purpose We aimed to evaluate the ablation outcomes of AT in patients with previous mitral valve (MV) surgery. Methods A total of 60 symptomatic patients with AT were enrolled. Activation mapping was performed during tachycardia in all patients as well as entrainment mapping when needed. Scar analysis was also performed when left atrial tachycardia detected. Results In 79 procedures, a total of 101 ATs were documented [35 (34.6%) ATs were right-sided, 65 (64.3%) ATs were left-sided and 1(0.9%) AT was biatrial]. Mean number of ATs per procedure was 1.4 ± 0.6. Macroreentry was the primary mechanism in right and left atrium (97% and 66.1%, respectively). Localization and mechanisms of ATs were demonstrated in Figure-1. Anterior wall [53.2%(17.9%-74.6%)], septum [53.7% (34.7%-80.0%)] and roof [40.1% (21.3%-72.5%)] were the left atrial sites with highest ratio of low voltage areas . The mean follow-up duration was 33.4 ± 17.7 months. Freedom from ATa after index procedure was 78.3% at 12 months and 65.9 % at 24 months. After multiple procedures, freedom from ATa was 80%, during the follow-up. Conclusion Left ATs are more common compared to the right ATs and macroreentry is the major mechanism in both right- & left ATs. RF ablation of ATs had favourable long-term outcomes in patients with MV surgery.