Sample Entropy Analysis of Noisy Atrial Electrograms during Atrial Fibrillation

Most cardiac arrhythmias can be classifed as atrial futter, focal atrial tachycardia, or atrial fbrillation. Tey have been usually treated using drugs, but catheter ablation has proven more efective. Tis is an invasive method devised to destroy the heart tissue that disturbs correct heart rhythm. In order to accurately localise the focus of this disturbance, the acquisition and processing of atrial electrograms form the usual mapping technique. Tey can be single potentials, double potentials, or complex fractionated atrial electrogram (CFAE) potentials, and last ones are the most efective targets for ablation. Te electrophysiological substrate is then localised by a suitable signal processing method. Sample Entropy is a statistic scarcely applied to electrograms but can arguably become a powerful tool to analyse these time series, supported by its results in other similar biomedical applications. However, the lack of an analysis of its dependence on the perturbations usually found in electrogram data, such as missing samples or spikes, is even more marked. Tis paper applied SampEn to the segmentation between non-CFAE and CFAE records and assessed its class segmentation power loss at diferent levels of these perturbations. Te results confrmed that SampEn was able to signifcantly distinguish between non-CFAE and CFAE records, even under very unfavourable conditions, such as 50% of missing data or 10% of spikes.