Relationship Between Sinus Rhythm Late Activation Zones and Critical Sites for Scar-Related Ventricular Tachycardia

Abstract

Background It is not known if the most delayed late potentials are functionally most specific for scar-related ventricular tachycardia (VT) circuits. Methods and Results Isochronal late activation maps (ILAM) were constructed to display ventricular activation during sinus rhythm over eight isochrones. Analysis was performed at successful VT termination sites and prospectively tested. 33 patients with 47 scar-related VTs where a critical site was demonstrated by termination of VT during ablation were retrospectively analyzed. In those that underwent mapping of multiple surfaces, 90% of critical sites were on the surface that contained the latest late potential. However, only 11% of critical sites were localized to the latest isochrone (87.5–100%) of ventricular activation. The median percentage of latest activation at critical sites was 78% at a distance from the latest isochrone of 18 mm. Sites critical to reentry were harbored in regions with slow conduction velocity, where 3 isochrones were present within a 1 cm radius. 10 consecutive patients underwent ablation prospectively guided by ILAM, targeting concentric isochrones outside of the latest isochrone. Elimination of the targeted VT was achieved in 90%. Termination of VT was achieved in 6 patients at a mean ventricular activation percentage of 78%, with only 1 requiring ablation in the latest isochrone. Conclusions Late potentials identified in the latest isochrone of activation during sinus rhythm are infrequently correlated with successful ablation sites for VT. The targeting of slow conduction regions propagating into the latest zone of activation may be a novel and promising strategy for substrate modification.

Utility of ripple mapping for identification of slow conduction channels during ventricular tachycardia ablation in the setting of arrhythmogenic right ventricular cardiomyopathy

“…The median ratio of RMCC ablated per patient was 1 (IQR, 0.6-1). 13 The latest activation ripple is consistent with the latest isochrones of activation in these patients ( Figures 1D-F and 2D). In contrast, Figure 2C shows examples of retrospectively identified RMCC remnants following ablation.…”

“…(corresponding to the latest isochrones of RMCC) comprise optimal ablation targets 13,[17][18][19][20]. Current techniques using endocardial and epicardial VT substrate ablation in ARVC provide 71% long-term VT-free survival 21.…”

A Prospective Study of Ripple Mapping the Post-Infarct Ventricular Scar to Guide Substrate Ablation for Ventricular Tachycardia

“…13,14 Adjustment of the voltage threshold has been used to identify channels of preserved myocardium within scar, but because voltage is annotated to the electrogram peak, these regions are usually formed of far-field signal. 15 Manual tagging of abnormal potentials or manual adjustment of activation time using color-coded isochronal activation maps can highlight local activation through scar, but are challenging with high-density point collection, and annotation as a single activation time is suboptimal at sites with fractionated or multiple late 12 Adjusting the window-of-interest post QRS has been used to highlight sites of late activation but ignores all local signals within the time window spanned by the QRS complex. 16 In this study, we found that RM overcame some of the practical limitations of characterizing the VT substrate using conventional 3-dimensional mapping techniques.…”

Challenges and Pitfalls of Entrainment Mapping of Ventricular Tachycardia

“…20 In Figure 2B, a multicomponent local electrogram signal is recorded during VT. One component is mid-diastolic and highly fractionated (A), with a lower amplitude than the component activated during the QRS (B). Pacing performed at 10 mA resulted in acceleration of the tachycardia with nearconcealed fusion.…”