Simplifying atrial tachycardia ablation: high density mapping of slow conduction sites during sinus rhythm identifies critical isthmuses of atrial tachycardias
S Hess, A Bernard, A K Gamer, F Cuculi, A JadidiAbstract
Background
Identifying the critical isthmus (CI) for atrial tachycardia (AT) often requires mapping during tachycardia. This study investigates whether sinus rhythm (SR) mapping can reliably detect and eliminate all potential slow conduction zones predisposing to AT.
Methods
Patients with a history of AT (focal or reentrant) who underwent catheter ablation with 3D high-density mapping were enrolled. Activation and voltage mapping was performed during AT, with SR restored by overdrive pacing or cardioversion when necessary. SR voltage maps (n=32) and paced maps from crista terminalis (n=5) with cutoff values of 0.05 mV to 0.5 mV were then obtained and compared to AT maps to identify CI, defined by electrograms with diastolic potentials and prolonged, fragmented morphology at slow conduction sites with optimal post-pacing interval (PPI). Ablation targeted these slow conduction areas during SR, with procedural success confirmed by acute AT non-inducibility and follow-up.
Results
Thirty-seven patients (mean age: 70.80 ± 9, 16 (43.24%) female, 23 Redo procedures) presented with AT. Voltage mapping during AT revealed a mean value of bipolar voltage (including both the near-field and far-field components), near-field and far-field EGM duration of 0.26 ± 0.27 mV and 95.79 ± 40.19 ms at CI. The mean value of bipolar voltage (near-field and far-field component), near-field and far-field EGM duration during SR corresponding to CI in AT were 0.31 ± 0.21 mV and 86.30 ± 31.30 ms, respectively. SR voltage maps reliably identified CIs, showing prolonged, fractionated EGMs with low bipolar voltage. Ablation during SR achieved AT non-inducibility in all cases, with arrhythmia freedom in 28/37 (75.68%) cases at mean follow up of 7.14 month.
Conclusion
The findings demonstrate that targeting conduction abnormalities during SR is sufficient for procedural success, eliminating the need for successive tachycardia induction, mapping and ablation.