How a Topological Mindset May Offer Extra Control During Mapping and Ablation of Left-Sided Reentrant Atrial Tachycardia.

Background: Reentry (macro or localized) is historically described as multiple pathways that are separated by barriers (either anatomic or functional) and involve active and passive loops (identified by electro-anatomic and entrainment mapping, EAM/ETM). Some reentrant atrial tachycardia (AT) cases are characterized by challenging activation patterns and unexpected ablation responses. A recent translational study, focusing on topology (TOP) and the role of boundaries, suggests that thinking topology within EAM/ETM might offer extra control during mapping and ablation of reentrant AT. We aimed to propose and prospectively validate a workflow (EAM/ETM+TOP) in which we integrate topological thinking within an EAM/ETM workflow for mapping and ablation of left-sided (left atrium) AT.

Methods: The integrated workflow was performed in 88 left atrium reentrant AT cases. After EAM/ETM, the number of loops and potential ablation strategy were verified against the number of critical and noncritical boundaries (critical boundary [CB], non-CB). Linear radiofrequency lesions were deployed to connect both CBs, preferably by one direct CB-CB line.

Results: EAM/ETM+TOP-based mapping was feasible in all cases and led to a diagnosis of a 2B topology with single-loop activation in 33 cases and a≥3B topology with dual-loop activation in 55 cases. In 87 out of 88 cases, subsequent ablation via a direct CB-CB approach (n=75), an indirect CB-non-CB-CB (n=9), or an indirect CB-non-CB-non-CB-CB approach (n=3) led to successful termination of AT. No unexpected changes in tachycardia cycle length occurred. After a median follow-up of 356 (inter-quartile range, 228-537) days, 16 patients experienced recurrence of AT (18%).

Conclusions: Thinking topology within an EAM/ETM workflow may offer extra control during mapping and ablation of left-sided reentrant AT.