Impact of Pulmonary Vein Isolation on Atrial Fibrillation Organisation: Correlation of Intracardiac and Surface Electrocardiogram Measures.

Introduction: Electrical activity in atrial fibrillation (AF) ranges from organized focal drivers to multiple wavelet re-entry. Understanding the effect of pulmonary vein isolation (PVI) on AF organization is clinically important, as it may optimize treatment strategies and outcomes. This study investigates the impact of PVI on AF organization and explores whether ventricular response regularity, measured from surface electrocardiograms (ECGs), reflects AF dynamics and electrophenotype.

Methods: Patients undergoing first-time PVI at Imperial College Healthcare NHS Trust between 2014 and 2022 were assessed pre- and post-PVI. AF organization was quantified using Shannon entropy (ShEn) and Sample entropy (SampEn) from coronary sinus (CS) electrograms. Ventricular response regularity was evaluated using surface ECG RR interval (RRI) variability and SampEn.

Results: PVI reduced ShEn and SampEn across all CS channels (e.g., SampEn CS 3-4: pre-ablation = 0.907 ± 0.512 vs. post-ablation = 0.790 ± 0.446, p < 0.001). Atrial ShEn and SampEn were correlated with ventricular response both pre- and post-ablation (e.g., correlations between atrial SampEn CS 3-4 and the following ventricular metrics: percentage of RRIs > 50 ms difference: r = 0.077, p = 0.008; normalized mean RRI difference: r = 0.144, p < 0.001; and normalized SampEn: r = 0.168, p < 0.001).

Conclusion: The reduction in atrial ShEn and SampEn post-PVI indicates increased AF organization. The significant correlation between atrial entropy and ventricular variability suggests that AF organization affects ventricular response, assessed via surface ECG metrics. These findings highlight the potential of ECG-based measures as proxies for intracardiac AF organization.