A Fractionation-based Local Activation Wave Detector for Atrial Electrograms of Atrial Fibrillation

Abstract

Atrial fibrillation (AF) electrograms (EGMs) present high heterogeneity of morphologies and amplitudes that turns the detection of their local activation waves (LAWs) a very hard task to perform. In this study, a novel fractionation-based LAW detector for bipolar EGMs is introduced. The method modifies traditional Botteron's band-pass filtering, decreasing its low cut-off frequency from 40 to 20 Hz, thus benefiting slow local activations detection. Furthermore, high and low amplitude activations in complex fractionated atrial electrograms (CFAEs) are equalized, thus facilitating the detection of low amplitude activations. A minimum refractory period of 50 ms is imposed between activations, however, additional minor activations are later sought for intervals longer than the median cycle length. All the LAWs from a set of 40 real bipolar EGMs, mostly CFAEs, were manually annotated by expert physicians and served to evaluate performance. Detections closer than 40 ms to a manual annotation were considered as correct. Detection results provided 95.41%, 92.13% and 96.37% in Sensitivity, Accuracy and Precision for CFAEs, respectively, whereas for less fractionated EGMs they were 100% in any case. Therefore, the new LAW detector has provided robust performance even under highly fractionated EGMs.