Substrate characterization and catheter ablation in patients with scar‐related ventricular tachycardia using ultra high‐density 3‐D mapping

Background Ablation of scar-related ventricular tachycardia (VT), especially in non-inducible VT or hemodynamically unstable patients, can be challenging. Thus, we evaluated feasibility of an ultra high-density 3D-mapping approach to characterize the ventricular substrate and, if possible, to map VT. Methods and results Twenty-two patients (67±2 years, mean LV-EF 36±3%) with both ischemic and non-ischemic cardiomyopathy and documented VT underwent mapping and catheter ablation using a 64-electrode mini-basket catheter. Substrate characterization included ultra high-density voltage maps, identification of areas of slow conduction and late potentials. Whenever VT was inducible activation mapping was performed. In 13/22 patients the presumed clinical VT (in 16/22 any VT) was inducible. A total of 50 maps were generated (22 substrate maps, 28 during VT), mapping time was 33±4 minutes, number of points was 10937±1923. Low voltage areas were related with the site of origin in all mapped VT. Isochronal maps indicated areas of slow conduction in 14/22 patients, all in border zone scar. In 95% of patients late potentials were found. Mapping time during VT was 9±2 minutes, number of points 6740±1140. Covered cycle length was 82±5% (16 re-entry, 10 focal and 2 undetermined). During 4 months follow-up 90% remained free from VT recurrence. Conclusion Ultra high-density mapping in patients with scar-related VT is feasible, safe and enables detailed insight into tachycardia mechanisms. Critical sites can be identified (1) by precise substrate characterization when VT is not inducible or hemodynamically not tolerated and (2) during short lasting episodes of VT in order to guide catheter ablation. This article is protected by copyright. All rights reserved