Quantification and analysis of atrial focal activity in atrial fibrillation using electrocardiographic imaging and flattening algorithms

Abstract

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia, yet understanding its causes and finding effective treatments remains a challenge. To address this, researchers are developing innovative approaches based on the identification and analysis of focal sources, which have been recognised as important in AF initiation. Non-invasive techniques, such as body surface potential mapping (BSPM) and electrocardiographic imaging (ECGI), have emerged as valuable tools for studying AF mechanisms. However, analyzing the data obtained from these techniques is currently impractical, and there is a lack of a standardized reference system available for comparing atrial regions and patients. The integration of ECGI with flattening algorithms shows promise as an experimental tool that converts complex 3D atrial geometry into a 2D representation, enabling localized and quantitative analysis of cardiac electrical activity. In this context, the objective of this study is to combine these methodologies and establish a pipeline for constructing a common reference system that facilitates quantitative and localized analysis of focal sources in the left atria (LA). To do so, this research employed ECGI data obtained from a cohort of nine patients who underwent ablation procedures provided by Universitat de València, along with a flattening algorithm developed at Universitat Pompeu Fabra. Preprocessing of the data involves optimizing geometries and providing inputs for the flattening algorithm. Moreover, a new region division is introduced to enable a more localized and specific analysis of the pulmonary veins (PV) and left atrial appendage (LAA). A statistical analysis is conducted, quantifying the total number of focal sources and foci density in different regions and investigating the differences in patient outcomes between termination and non-termination cases. The results of the study indicate differences between patients and groups as observed through the regional analysis. However, due to the limited number of patients involved, it is not yet possible to draw definitive clinical conclusions. Overall, the study provides a novel approach to quantitatively and locally analyze focal sources in the LA, and offers to advance our understanding of AF initiation mechanisms and provide valuable insights in ablation therapy guidance.