Please cite this article in press as: E.J. Ciaccio, et al., Optimization of novel spectral estimator for fractionated electrogram analysis is helpful to discern atrial fibrillation type, Comput. Methods Programs Biomed. (2014), http://dx.doi.org/10.1016/j.cmpb.2014.06.006 ARTICLE IN PRESS COMM-3812; No. of Pages 8 c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e x x x ( 2 0 1 4 ) xxx–xxx jo ur nal ho me p ag e: www.intl.elsevierhealt h.com/journals/cmpb Optimization of novel spectral estimator for fractionated electrogram analysis is helpful to discern atrial fibrillation type Edward J. Ciaccio * , Angelo B. Biviano, Hasan Garan Department of Medicine, Division of Cardiology, Columbia University Medical Center, New York, USA a r t i c l e i n f o Article history: Received 13 January 2014 Received in revised form 11 June 2014 Accepted 13 June 2014 Keywords: Atrial fibrillation Dominant frequency Electrograms Parameters Spectral estimation a b s t r a c t Introduction: Paroxysmal versus persistent atrial fibrillation (AF) can be distinguished based on differences in the spectral parameters of fractionated atrial electrograms. Maximization of these differences would improve characterization of the arrhythmogenic substrate. A novel spectral estimator (NSE) has been shown previously to provide greater distinction in AF spectral parameters as compared with the Fourier transform estimator. Herein, it is described how the differences in NSE spectral parameters can be further improved. Method: In 10 persistent and 9 paroxysmal AF patients undergoing electrophysiologic study, fractionated electrograms were acquired from the distal bipolar ablation electrode. A total of 204 electrograms were recorded from the pulmonary vein (PV) antra and from the anterior and posterior left atrial free wall. The following spectral parameters were measured: the dominant frequency (DF), which reflects local activation rate, the DF amplitude (DA), and the mean spectral profile (MP), which represents background electrical activity. To optimize differences in parameters between paroxysmal versus persistent AF patients, the NSE was varied by selectively removing subharmonics, using a threshold. The threshold was altered in steps to determine the optimal subharmonics removal. Results: At the optimal threshold level, mean differences in persistent versus paroxysmal AF spectral parameters were: DA = +0.371 mV, DF = +0.737 Hz, and MP = -0.096 mV. When subharmonics were not removed, the differences were substantially less: DA = +0.301 mV, DF = +0.699 Hz, and MP = -0.063 mV. Conclusions: NSE optimization produces greater spectral parameter difference between per- sistent versus paroxysmal AF data. Quantifying spectral parameter differences can be assistive in characterizing the arrhythmogenic substrate. © 2014 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Fractionated atrial electrograms are useful to characterize the arrhythmogenic atrial fibrillation (AF) substrate for catheter ∗ Corresponding author at: Presbyterian Hospital 7W-318, 630 West 168th Street, Columbia University, New York, NY 10032, USA. Tel.: +1 212 305 5447; fax: +1 212 342 0447. E-mail address: ciaccio@columbia.edu (E.J. Ciaccio). ablation [1–4]. Since fractionated electrograms are complex, frequency analysis is often used for characterization [4]. It has been shown that there are significant differences in the spectral parameters of paroxysmal versus persistent AF elec- trograms. It would be desirable to maximize these differences http://dx.doi.org/10.1016/j.cmpb.2014.06.006 0169-2607/© 2014 Elsevier Ireland Ltd. All rights reserved.