Statistical characterisation of endocardial breakthroughs in atrial fibrillation

Author: Jay Nguyen

Nguyen, Jay, 2022 Statistical characterisation of endocardial breakthroughs in atrial fibrillation, Flinders University, College of Science and Engineering

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Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans. During AF, phenomena known as endocardial breakthroughs have been observed, which have been proposed as the mechanism for maintaining AF. An important question that is not fully understood is whether endocardial breakthroughs occur randomly, or if they perhaps represent ‘drivers’ of AF. In this study, the statistical properties of endocardial breakthroughs were analysed by applying the Renewal theory. It was recently proposed as a quantitative framework for phase singularities, a stochastic electrical activity during atrial fibrillation. This study was based on the HD-grid catheter data from AF patients. Pre-processing of the signal and phase mapping were provided by Flinders Heart Rhythm Research Group. Then novel custom image algorithm was developed to detect endocardial breakthroughs and calculate the inter-formation times. Subsequently, statistical analyses were performed to test the statistical distribution of inter-formation times and the impact of different factors on the formation of endocardial breakthroughs during AF. This study found that the inter-formation times of endocardial breakthroughs were statistically independent and has an exponential distribution in AF patient's hearts. It means that endocardial breakthrough is a stochastic process with no underlying constant driver and does not constantly drive AF. It also means that Renewal theory is applicable to understand endocardial breakthroughs. The exponential probability distribution of inter-formation times and means that the formation rate of endocardial breakthroughs is measurable. The measurable rate allows the characterisation of endocardial breakthroughs during the maintenance of AF. Another finding was that clinical types of AF have a significant impact on the formation of endocardial breakthroughs. It is consistent with previous studies on the role of endocardial breakthroughs in AF progression. Its incidence was found to relate to the damage of sustained AF. Its propagation contributes to the complexity of electrical patterns sustaining AF.

Keywords: atrial fibrillation, endocardial breakthroughs, Renewal theory, electrogram data, signal processing, phase mapping, inter-formation times

Subject: Engineering thesis

Thesis type: Masters
Completed: 2022
School: College of Science and Engineering
Supervisor: A\Prof Anand Ganesan, Dr Dhani Dharmaprani, A\Prof Kenneth Pope