Optimization of novel spectral estimator for fractionated electrogram analysis is helpful to discern atrial fibrillation type

• A novel spectral estimator is used to discern paroxysmal versus persistent atrial fibrillation fractionated electrograms.
• The estimator is improved by selectively imparting antisymmetry to basis vectors used to construct the power spectrum.
• This preprocessing step leads to improved differentiation of spectral parameters in paroxysmal versus persistent atrial fibrillation fractionated electrograms.
• The improvement is potentially useful to better discern regions of atrial fibrillation substrate that should be targeted for catheter ablation.
• This method has been shown to provide better discernment of atrial fibrillation type as compared with the Fourier transform estimator.

IntroductionParoxysmal 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.MethodIn 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.ResultsAt the optimal threshold level, mean differences in persistent versus paroxysmal AF spectral parameters were: ΔDA = +0.371 mV, ΔDF = +0.737 Hz, and ΔMP = −0.096 mV. When subharmonics were not removed, the differences were substantially less: ΔDA = +0.301 mV, ΔDF = +0.699 Hz, and ΔMP = −0.063 mV.ConclusionsNSE optimization produces greater spectral parameter difference between persistent versus paroxysmal AF data. Quantifying spectral parameter differences can be assistive in characterizing the arrhythmogenic substrate.