Left atrial substrate characterization based on bipolar voltage electrograms acquired with multipolar, focal and mini-electrode catheters– the CHAZE-Substrate study

Background Bipolar voltage (BV) electrograms for left atrial (LA) substrate characterization depend on catheter design and electrode configuration. The aim of the study was to investigate the relationship between the BV amplitude (BVA) using four different catheters and to identify their specific LA cutoffs for scar and healthy tissue. Methods Consecutive high-resolution electroanatomic mapping was performed using a multipolar Orion catheter (Orion-map), a duo-decapolar variable circular mapping catheter (Lasso-Map) and an irrigated focal ablation catheter with minielectrodes (Mifi-map). Virtual remapping using the Mifi-map was performed with a 4.5 mm tip-size electrode configuration (Nav-map). BVAs were compared in voxels of 3×3×3 mm3. The equivalent BVA cutoff for every catheter was calculated for established reference cutoff values of 0.1 mV, 0.2 mV, 0.5 mV, 1.0 mV, and 1.5 mV. Results We analyzed 25 patients (72% men, age 68±15 years). For scar tissue, a 0.5 mV cutoff using the Nav corresponds to a lower cutoff of 0.35 mV for the Orion and of 0.48 mV for the Lasso. Accordingly, a 0.2 mV cutoff corresponds to a cutoff of 0.09 mV for the Orion and of 0.14 mV for the Lasso. For a healthy tissue cutoff at 1.5 mV, a larger BVA cutoff for the small electrodes of the Orion and the Lasso was determined of 1.68 mV and 2.21 mV, respectively. Conclusions When measuring LA BVA in scar and healthy tissue, relevant differences were seen between focal, multielectrode and mini-electrode catheters. Adapted cutoffs for scar and healthy tissue are required. ### Competing Interest Statement Sven Knecht has received funding of the "Stiftung für Herzschrittmacher und Elektrophysiologie" and the "Freiwillige Akademische Gesellschaft Basel". Patrick Badertscher has received research funding from the "University of Basel", the "Stiftung für Herzschrittmacher und Elektrophysiologie" and the "Freiwillige Akademische Gesellschaft Basel". Beat Schaer reports speaker's bureau for Medtronic. Stefan Osswald received research grants from the Swiss National Science Foundation and Swiss Heart Foundation, Foundation for CardioVascular Research Basel, and F. Hoffmann-La Roche Ltd., and educational and speaker grants from F. Hoffmann-La Roche Ltd., Bayer, Novartis, Sanofi AstraZeneca, Daiichi-Sankyo, and Pfizer. Christian Sticherling: Member of Medtronic Advisory Board Europe and Boston Scientitic Advisory Board Europe, received educational grants from Biosense Webster and Biotronik and a research grant from the European Union's FP7 program and Biosense Webster and lecture and consulting fees from Abbott, Medtronic, Biosense-Webster, Boston Scientific, Microport, and Biotronik all outside the submitted work Michael Kühne reports personal fees from Bayer, personal fees from Böhringer Ingelheim, personal fees from Pfizer BMS, personal fees from Daiichi Sankyo, personal fees from Medtronic, personal fees from Biotronik, personal fees from Boston Scientific, personal fees from Johnson&Johnson, grants from Bayer, grants from Pfizer, grants from Boston Scientific, grants from BMS, grants from Biotronik, all outside the submitted work. Others have nothing to declare. ### Clinical Trial NCT04095559 ### Funding Statement The study was supported by an investigator sponsored grant (Boston Scientific, ISRRM10392). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics Committee Northwest and Central Switzerland I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Data available on request from the authors