Dispersion of Activation in Single-Beat Global Maps During Programmed Ventricular Stimulation Identifies Infarct-Related Ventricular Tachycardia Isthmus Sites.

BACKGROUND

Electrophysiological characterization of ventricular tachycardia (VT) isthmus sites is complex and time-consuming. We aimed at developing and validating a global mapping strategy during programmed ventricular stimulation (PVS) to reveal the underlying electrophysiological properties of the infarct-related substrate and to enable identification of highly heterogeneous activation sites associated with protected VT isthmus sites.

METHODS AND

RESULTS

Experimental study that included 22 pigs with established myocardial infarction undergoing in vivo characterization of the anatomical and functional myocardial substrate associated with potential arrhythmogenicity. High-density sequential activation maps during ventricular pacing and VT were compared with single-beat maps using a 64-pole basket catheter positioned in the left ventricle. Further analyses were performed using a novel local activation time-dispersion score to identify regional activation time heterogeneities on both baseline drive pacing and each of the extrastimuli of the PVS protocol. Basket catheter splines covered a median of 81.2% of the endocardial surface of the left ventricle. Basket-catheter-derived single-beat activation maps (N=16) during pacing showed a linear relationship with high-density sequential activation maps. Induction of ventricular arrhythmias was associated with higher local activation time-dispersion score values on single-beat global maps during PVS (N=6, 46 arrhythmia induction attempts). Single-beat-derived local activation time-dispersion score maps during successive coupled extrastimuli of the PVS showed a progressive increase in the predictive performance to identify monomorphic VT isthmus sites within the scar region (area under the curve = 0.779 in S2, area under the curve = 0.859 in S4; N=7).

CONCLUSIONS

Sixty-four-pole-derived single-beat local activation time-dispersion score global maps during PVS identify infarct-related endocardial regions with highly heterogeneous activation times that are associated with protected VT isthmus sites.