Repolarization time map in catheter ablation for scar-related reentrant ventricular tachycardia

Ventricular tachycardias (VTs) associated with scar tissue involve reentry mechanisms influenced by both conduction abnormalities and repolarization heterogeneity. However, existing mapping techniques have predominantly focused on conduction delay.

This retrospective study analyzed 33 consecutive cases of catheter ablation for sustained VT. The EnSite system was employed to measure repolarization time (RT) with a high-pass filter setting of 0.05 Hz. We compared the characteristics and concordance rates of short RT areas, defined as white or red-colored regions, with those identified through conventional mappings in relation to ablation targets. These short RT areas were defined based on the longest interval from the QRS onset to the maximal dV/dt point of unipolar potentials, which was divided into eight equal segments.

Out of 31 VTs across 26 cases, we found that 18 (58%) of the identified ablation targets corresponded to deceleration zones (DZs). Of them, 16 (89%) also overlapped with areas of short RTs. Notably, among the remaining 13 VTs without ablation targets corresponding to DZs, 9 (69%) had ablation targets located in areas with short RTs. The distribution analysis revealed that 84% of short RT regions were located near the exit site, whereas 75% of DZs were situated near the entrance site. The distance between the two was 16 mm (interquartile range: 6.5-27.5 mm).

This study underscored the potential of RT mapping in identifying ablation targets in scar-related VTs. Incorporating both repolarization heterogeneity and conduction delay could significantly enhance the understanding of the intricate circuits involved in these arrhythmias.