Atrial contractile and electrical remodeling is associated with more complex conduction patterns in patients without history of atrial fibrillation: a high-density epicardial mapping study
Authors: Kawczynski M , Maesen B , Zeemering S , Isaacs A , Maessen J , Verheule S , Schotten U , Bidar E 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work was supported by the Netherlands Heart Foundation (CVON2014-09, RACE V Reappraisal of Atrial Fibrillation: Interaction between hyperCoagulability, Electrical remodelling, and Vascular Destabilisation in the Progression of AF), the European Union (ITN Network Personalized Therapies for Atrial Fibrillation: a translational network: PersonalizeAF, grant 860974, CATCH ME: Characterizing Atrial fibrillation by Translating its Causes into Health Modifiers in the Elderly, No. 633196).

Background
Early atrial remodeling refers to a concept where atrial structural, functional, and electrophysiological changes may be present without clinical manifestation of atrial arrhythmias. (1) However, it is currently unknown how electrophysiological and functional atrial properties are related, especially in the early stages of atrial remodeling.

Purpose
To investigate the relationship between electrophysiological properties of the atria, determined by intraoperative high-density epicardial mapping after AF-induction, and echocardiographic and electrocardiographic parameters in patients without a history of AF undergoing cardiac surgery.

Methods
All patients underwent functional and electrophysiological analysis of both atria using preoperative transthoracic echocardiography, electrocardiography, and intraoperative biatrial high-density epicardial mapping. Postoperatively, all patients were continuously monitored for occurrence of new-onset postoperative AF (POAF). In addition to univariable and multivariable analysis, cluster analysis was performed to identify distinct clusters of subjects for epicardial mapping parameters.

Results
The study population consisted of 38 patients undergoing coronary artery bypass grafting, isolated aortic valve replacement, or the combination of both. All patients completed 1-year continuous rhythm monitoring and 19 patients (50%) developed POAF. There was a greater number of waves/cycle (4.57±1.55 vs. 3.98±1.63, p=0.04) and breakthrough (BT) waves/cycle (1.16±0.58 vs. 0.88±0.60, p=0.01) in the RA compared to the LA (Figure 1). Also, there was a lower conduction velocity (CV) in the RA than in the LA (0.71±0.10m/s vs 1.19±0.36m/s, p&lt;0.01) (Figure 1). Average waves/cycle were significantly correlated with reduced P-wave duration and P-wave amplitude (Spearman’s rho=-0.32, p=0.04, and Spearman’s rho=-0.32, p=0.04, respectively). Also, there was significant negative correlation between LA booster function and LA waves/cycle (Spearman’s rho=-0.55, p&lt;0.01). Survival analysis revealed that older age, lower P-wave amplitude, reduced LA booster function, and increased RA waves/cycle were associated with increased occurrence of POAF (Figure 2). Cluster analysis was performed for RA and LA epicardial mapping parameters, which identified 2 distinct clusters: cluster 1 consisted of patients with more complex atrial electrical conduction patterns, and cluster 2 less complex atrial electrical conduction patterns. Multivariable analysis showed that reduced LA booster function was independently associated with a cluster representing more complex atrial electrical conduction patterns in the LA (OR=1.13, 95% CI: 1.02-1.25, p=0.02).

Conclusion
In patients without a history of AF, reduced LA contractile function and lower P-wave amplitude are associated with more complex electrical conduction patterns in acutely induced AF, potentially representing an early step in the atrial remodeling process.