High-density characterization of the sinus rhythm: a new functional substrate map of scar-related atrial tachycardia

BackgroundReentrant atrial tachycardias (ATs) utilize critical isthmus (CI) for the maintenance of the circuit. The electrophysiological characteristics and clinical implications of the targeted CI regions of reentrant ATs during sinus rhythm (SR) were not clear. Therefore, our research aims at studying the electrical properties of the CI sites for scar-related reentrant ATs and the functional substrate mapping identified during SR.MethodsPatients mapped with high-density catheters during SR and reentrant ATs were retrospectively analyzed. The CI regions of the reentrant ATs were confirmed by the combination of the activation map and the entrainment. The substrate mapping was analyzed for wavefront propagation, conduction velocity, and electrogram patterns.ResultsTwenty patients with 22 reentrant ATs that underwent high-density maps were analyzed at 2 hospitals. Mapping performed during SR identified a scar region of 23.0 +/- 13.6% of the left atrium. Regions of the CI in SR were characterized by low voltage (0.3 +/- 0.2 mV), conduction slowing (0.4 +/- 0.2 m/s), and fractionated electrogram (duration 62.5 +/- 13.9 ms). Substrate mapping during SR showed that the regions of the CI located with the low-voltage zone in 16 out of 22 CI (72.7%), the deceleration zone in 15 out of 22 CI (68.2%), and late atrial activation in 12 out of 22 CI (54.5%). Targeting regions of CI achieve 94% of termination or change of the reentrant circuit. At 6.2 +/- 7.1 months, there was 75% freedom from atrial arrhythmia.ConclusionsNovel high-density mapping can identify the functional substrates during SR and guide ablation. Low-voltage areas with conduction slowing are putative predictors of the CI for the maintenance of the reentrant ATs.

Automated summary

This study aims to investigate the electrophysiological characteristics and clinical implications of the critical isthmus (CI) for the maintenance of scar-related reentrant atrial tachycardias (ATs) during sinus rhythm (SR), and to map the functional substrate of the CI during SR. The results showed that the CI regions during SR were characterized by low voltage, conduction slowing, and fractionated electrogram. Targeting these regions achieved a high rate of termination or change of the reentrant circuit.