Optimizing Atrial Electrogram Classification Based on Local Ablation Outcome in Human Atrial Fibrillation

Arthur Bezerra1, Takashi Yoneyama1, Diogo Soriano2, Giorgio Luongo3, Xin Li4, Flavia Ravelli5, Michela Masè5, Gavin Chu4, Peter Stafford4, Fernando Schlindwein4, G. Andre Ng4, Tiago Paggi de Almeida4
1Instituto Tecnológico de Aeronáutica, 2Universidade Federal do ABC, 3Karlsruhe Institute of Technology, 4University of Leicester, 5University of Trento


Aims: Changes in atrial fibrillation cycle length (AF-CL) are broadly used as a ‘ground truth’ to assess the effect of substrate modification during AF ablation. Increase in AF-CL following ablation has been reported before persistent AF (persAF) termination. There is, however, no consensus on how much of a change in AF-CL should be considered to characterise significant substrate modification. In this work, we sought to optimize thresholds for changes in coronary sinus CL (CS-CL) after local ablation using different atrial electrogram (AEG)-derived markers. Methods: 834 AEGs were collected from 11 patients undergoing persAF ablation. Pulmonary vein isolation was performed followed by AEG-guided ablation. All patients achieved AF termination as a result of ablation. CS-CL was measured before and after each ablation point. AEGs collected at regions in which ablation resulted in CS-CL increase above a certain threshold were labelled ‘target’, and those below this threshold were labelled ‘non-target’. Thresholds from 0 to 100 ms were investigated. Five AEG-derived markers were tested as classifiers for CS-CL changes: ICL (Biosense Webster), CFEMean (St. Jude Medical), Wave Similarity, Shannon Entropy and AEG-CL. The area under the receiver operating characteristic (AUROC) curve was used to assess the quality of classification for each. Results: Maximum AUROC was found at threshold values between 9 and 14 ms in all markers, with the exception of Shannon Entropy. The average AUROC among the five markers reached a maximum of 0.60 at threshold 10 ms, which is one of the points of smallest variance. Conclusion: Our results show good agreement between the markers, despite their different optimal thresholds. The 10 ms threshold is suggested as a starting setpoint for future studies seeking to identify AF ablation targets based on objective CL-based ‘ground truth’.