ISOLATION OF F-WAVE FROM ELECTROCARDIOGRAM USING NEW LMS ALGORITHM Edward J. Ciaccio * , Angelo B. Biviano and Hasan Garan Department of Medicine, Division of Cardiology Columbia University Medical Center, New York, USA Accepted 7 February 2014 Published ABSTRACT The electrocardiogram F-wave arising from atrial electrical activity is an important global measure for assessment of atrial ¯brillation (AF). However, successful F-wave extraction from the ventricular waveform can be problematic. Herein, a new F-wave isolation technique is introduced. For analysis, electrocardiogram lead I (termed un¯ltered or UNF-signals) was retrospectively analyzed (39 AF patients, 8.4-s recordings, 8192 sample points, 96 recordings in total). To measure the e±cacy of isolation techniques, a synthetic F-wave (7.29 Hz) and an interference were added to each electrocardiogram signal. In the resulting composite signals, the average electrocardiogram QRST complex template was subtracted from each actual QRST (AVG-isolation). The QRST template was also adjusted using a new adaptive least mean-squares (LMS) algorithm, and subtracted from each actual QRST (termed LMS-isolation). Four spectral parameters were measured to assess isolated F-wave quality: the dominant amplitude (DA), dominant fre- quency (DF) and mean/standard deviation in spectral pro¯le (MP/SP). Signi¯cant parameter di®erences between UNF/LMS and between AVG/LMS were determined. The electrocardiogram F-wave spectral parameters were sig- ni¯cantly improved by incorporating LMS-isolation as compared to no isolation ( p < 0:001). The F-wave spectral parameters were also signi¯cantly improved using LMS-isolation as compared with AVG-isolation (DA/MP/SP: p < 0:001; DF: p < 0:05). The DF was correctly identi¯ed as 7:29  0:10 Hz using ensemble spectral analysis with the following percentages (UNF: 24.0%, AVG: 69.8%, LMS: 80.2%), and Fourier spectral analysis with the following percentages (UNF: 15.6%, AVG: 60.4%, LMS: 75.0%). The LMS algorithm is helpful to isolate the electrocardiogram F-wave from the ventricular component as measured by spectral analysis, when compared to the use of an average QRST subtraction template. Keywords: Atrial ¯brillation; Electrocardiogram; F-wave; Least mean squares; Spectral estimation. INTRODUCTION The electrocardiogram F-wave is a surface lead mani- festation of ¯brillatory activity in the atria. Increasing attention has been given to this waveform, and its isolation from the ventricular signal is a matter of con- siderable interest and importance. 1 The potential applications of quantitative analysis of the F-wave, when it can be accurately separated from the ventricular component of the electrocardiogram, are many. For example, a large F-wave amplitude can be predictive of procedural termination in persistent AF patients, and it can be predictive of the freedom from recurrence in this patient group. 2 F-wave amplitude is useful as a nonin- vasive measure of AF regularity and is estimative of the characteristics of epicardial electrical activity. 3 The * Corresponding author: Edward J. Ciaccio, Department of Medicine, Division of Cardiology, Columbia University, Room PH7W- 318, 630 West 168th Street, New York NY 10032, USA. Tel: 212-305-5447; Fax: 212-342-0447; E-mail: ciaccio@columbia.edu Biomedical Engineering: Applications, Basis and Communications, Vol. 26, No. 6 (2014) 1450067 (10 pages) DOI: 10.4015/S1016237214500677 June 6, 2014 12:52:15pm WSPC/240-BME 1450067 ISSN: 1016-2372 3rd Reading 1450067-1