Intrascar ventricular tachycardia: New concept of scar-reentrant ventricular tachycardia

Temporal and Spatial Pacemap Parameters for Identification of Cardiac Surfaces with Critical Sites for Ventricular Tachycardia

INTRODUCTION

Multi-surface pacemapping may help identify the surface of interest in scar-related ventricular tachycardia. This study aimed to investigate the performance of pacemap parameters for detecting critical sites through multi-surface mapping.

METHODS AND RESULTS

In 26 patients who underwent scar-related ventricular tachycardia ablation, pacemap parameters including a matching score, the difference between the longest and shortest stimulus-QRS intervals (Δs-QRS), and the distance between the good pacemap sites were measured. The parameters were compared between surfaces with and without critical sites and ablation outcomes. A total of 941 pacemaps at 56 surfaces targeting 35 ventricular tachycardias were analyzed. A greater Δs-QRS (40 vs. 8 ms, P<0.001) and longer distance between two good pacemap sites (24 vs. 13 mm, P<0.001) were observed on the surfaces with critical sites. A similar trend was seen in multi-surface pacemapping for the same ventricular tachycardias (52 vs 18 ms in Δs-QRS, P=0.021; 37 vs. 12 mm in distance, P=0.019), although the best pacemap scores were comparable (94 vs. 87, P=0.295). The Δs-QRS >20 ms and the distance >19 mm showed high positive likelihood ratios (19.8 and 6.1, respectively) for discriminating the surface harboring the critical site. Ablation of ventricular tachycardias fulfilling these parameters was successful on the surfaces, but without the required multi-surface ablation.

CONCLUSION

Temporal (Δs-QRS) and spatial (distance) parameters for good pacemap match sites were excellent markers for detecting the surface harboring critical sites in scar-related ventricular tachycardia. A multi-surface pacemapping can successfully identify the surface of interest. This article is protected by copyright. All rights reserved.