Spatial Correlation of Left Atrial Low Voltage Substrate in Sinus Rhythm versus Atrial Fibrillation: Identifying the Pathological Substrate Irrespective of the Rhythm

Abstract

Background: Low voltage substrate (LVS) identified during electroanatomical mapping is a potential target for atrial fibrillation (AF) ablation. However, it is not clear how the location and extent of LVS correlate between mapping in sinus rhythm (SR) and AF. Objectives: (1) Identify voltage dissimilarities between mapping in SR and AF. (2) Identification of regional voltage thresholds that improve cross-rhythm substrate detection. (3) Comparison of LVS between SR and native vs. induced AF. Methods: Forty-one ablation-naive persistent AF patients underwent high-density voltage mapping in SR and AF. Each patients voltage information was mapped to a joint geometry for analysis. Global and regional voltage thresholds in AF were identified which best match LVS < 0.5mV and < 1.0mV in SR. Additionally, the correlation between SR-LVS with induced vs. native AF LVS was assessed. Results: Substantial voltage differences (median: 0.52, IQR: 0.33-0.69, max: 1.19 mV) with predominance of the posterior/inferior LA wall exist between the rhythms. An AF threshold of 0.34mV for the entire atrium provides an accuracy, sensitivity and specificity of 69%, 67% and 69% to identify SR-LVS < 0.5mV, respectively. Lower thresholds for the posterior wall (0.27 mV) and inferior wall (0.3 mV) result in higher spatial concordance to SR-LVS (4% and 7% increase). Concordance with SR-LVS was higher for induced AF compared to native AF (AUC: 0.80 vs. 0.73). AF-LVS < 0.5mV corresponds to SR-LVS < 0.97mV using high-definition mapping (AUC: 0.73). Conclusion: The proposed voltage thresholds during AF maximise the consistency of LVS identification as determined during SR. Regional thresholds can further improve concordance.

A Review of Healthy and Fibrotic Myocardium Microstructure Modeling and Corresponding Intracardiac Electrograms

“…Different studies demonstrated discrepancies when using the same voltage threshold (for example, 0.5 mV) to distinguish healthy from pathological tissue when mapping during different rhythms (sinus rhythm and AF) ( Rodríguez-Mañero et al, 2018 ; Nairn et al, 2020b ; Nairn et al, 2022 ). Nairn et al (2022) looked at how the amplitude of EGMs changed when electroanatomical mapping was performed under three different rhythms (sinus rhythm, native AF, and induced AF). The authors proposed not only one single cut-off voltage value for the entire atrium but regional voltage thresholds to minimize the discrepancies between different mapping rhythms.…”