Ultra High-Density Mapping and Ablation of Localized Micro-Reentrant Tachycardias: Insight From the CHARISMA Registry

Background: Recent advancements in ultra-high-density mapping (UHDM) featuring automated functionalities have enhanced our understanding of micro-reentrant atrial tachycardias (mAT) circuits and the precise localization of the origin. Purpose: To evaluate the diagnostic support provided by an automated UHDM algorithm in guiding the ablation of mATs. Methods: Consecutive patients eligible for AT ablation in 22 Italian centers were prospectively enrolled. All ATs were comprehensively mapped in either the left or right atrium utilizing the RHYTHMIA mapping system. The LUMIPOINT tool was systematically employed to confirm electrogram fragmentation within this defined area. Results: Among 159 ATs analyzed, 97 (61.0%) were identified as macro-reentrant ATs, 50 (31.4%) as focal ATs and 12 (7.5%) as mATs. Concerning the mAT group, the targeted activity was localized in the anterior wall in 4 cases (33.3%), in proximity to PVs in 3 cases (25%), along the left ridge in 2 cases (16.6%), and at the roof, in the free wall and along the CTI in 1 case (8.3%), respectively. Low voltage areas (< 0.1 mV) were detected in all mAT cases and colocalized with the origin site. Over a median of 288 [248–349] days of follow-up, 5 (3.1%) patients suffered from an AT/AF arrhythmia recurrence: 3 (3.1%) were in the MAT group, 1 (2%) in the focal AT and 1 (8.3%) in the mAT group. Conclusion: A novel automated algorithm for mAT identification, coupled with ORION catheter, enables mAT description and transcatheter ablation of the localized origin of this rare form of AT results in a satisfactory procedural success rate. Trial Registration: Catheter Ablation of Arrhythmias With High-Density Mapping System in the Real World Practice (CHARISMA). http://clinicaltrials.gov/ Identifier: NCT03793998.