Activation signature valleys are predictive of macroreentrant atrial tachycardia bottlenecks where uniform low voltage and uniform slow conduction reside.

BACKGROUND

The activation signature (AS), that is, the number of recording sites activating per unit time, is useful to detect ventricular tachycardia isthmus location.

OBJECTIVE

We used the AS for atrial tachycardia (AT) analysis.

METHOD: In 40 index cases with macroreentrant AT, plus 4 repeat ablations, it was supposed that circuit bottlenecks, the locations of which are predicted ablation targets, could be defined by local activation time intervals in the cardiac cycle having minimized sites activating. Predicted and actual target parameter values were compared for voltage and electrical conduction vs peripheral (nontarget) sites.

RESULTS

Of 44 procedures, 35 had 1 predicted target, 7 had 2 targets, and 2 had 3 targets, as determined using the signature (N = 55 total targets). In 26 of 44 procedures, a predicted target approximately overlapped the actual target. The mean peripheral voltage was 0.71 ± 0.47 mV vs 0.29 ± 0.27 mV at the actual target and 0.28 ± 0.21 mV at the predicted target (P < .001). The peripheral voltage standard deviation was 1.14 ± 1.02 mV vs 0.20 ± 0.15 mV at the actual target and 0.26 ± 0.22 mV at the predicted target (P < .001). The coefficient of variation of the nearest-neighbor activation time difference, with lower values indicative of uniform slow conduction, was 1.99 ± 0.46 ms peripherally vs 1.50 ± 1.08 ms at the actual target and 0.73 ± 0.23 mV at the predicted target (P < .001).

CONCLUSION

The AS detects potential bottlenecks for predictive targeting in patients with AT, using differing criteria and often varying locationally from actual targeting, yet identifying areas with similarly uniform low voltage and uniform slow conduction. Predicted targets often coincide with voltage fissures, where sluggish conduction reinforces the excitable gap.