The dominant morphology of fractionated atrial electrograms has greater temporal stability in persistent as compared with paroxysmal atrial fibrillation

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Abstract

Background

Measurements of both the dominant frequency (DF) and the time series morphology of complex fractionated atrial electrograms (CFAE) are useful to distinguish persistent from paroxysmal atrial fibrillation (AF). In this study, an algorithm was devised to extract morphologic components according to frequency, and its usefulness for distinguishing CFAE was shown.

Method

CFAE of length 16 s were obtained at two sites each from the four pulmonary vein ostia (PV), and from anterior and posterior left atrial free wall (FW), in nine paroxysmal and 10 longstanding persistent AF patients. The DF was computed for each of two 8 s CFAE segments in each 16 s recording. Each CFAE segment was then transformed into a set of basis vectors, which represent electrogram morphology at each frequency. The dominant morphology (DM) is defined as the ensemble average of sequential signal segments, with the segment length equal to the period at the DF. The DMs of the two 8 s pairs were correlated. Normalized correlation coefficients were tabulated for all data, and separately for PV and FW. The means and coefficients of variation of the DM correlation coefficients were then plotted, and a linear discriminant function was used to classify persistent versus paroxysmal AF data. For comparison with DM results, CFE-mean and interval confidence level (ICL) were also calculated for persistent versus paroxysmal AF data.

Results

Mean correlation of the DM, 1st 8 s versus 2nd 8 s data, was 0.62+0.22 for persistent versus 0.50+0.19 for paroxysmal CFAE for all recording sites (p<0.001). At single anatomical locations, correlation was greater in persistents than paroxysmals at all sites, but achieved significance only at the left superior (p<0.001) and right superior (p<0.05) PV. Spatial variation in correlation coefficient was greater in paroxysmal than persistent AF (not significant). Using the means of DF correlation coefficients, 17/19 patients were classified correctly. The CFE-mean parameter averaged 89.01±20.99 ms in persistents versus 93.96±33.81 ms in paroxysmals (p<0.05), while ICL averaged 94.54±18.52 deflections/8 s for persistents versus 90.70±19.28 deflections/8 s for paroxysmals (p<0.05).

Conclusions

In CFAE recordings, the DM parameter was found to have greater temporal morphologic variation in paroxysmal as compared with persistent AF data (p<0.001). In contrast, only moderate significance between paroxysmal versus persistent AF data was found when using the of CFE-mean and ICL parameters (p<0.05). The DM parameter may thus be useful as a new measure to discern both temporal and spatial variations in CFAE in paroxysmal versus persistent AF recordings.

Section snippets

Background

Isolation of electrical activity in the pulmonary veins (PV) is a first step to prevent atrial fibrillation (AF) when drug therapy fails [1], [2]. This technique as a sole procedure works reasonably well in patients with paroxysmal AF [3]. Ablation of other areas of the left atrium may eliminate arrhythmogenic sites, stop AF, and prevent its recurrence in both paroxysmal [4] and persistent AF substrates [5], although additional procedures may be required, particularly in cases of persistent AF

Clinical data acquisition and electrophysiologic mapping

Atrial electrograms were recorded from 19 patients referred to the Columbia University Medical Center cardiac electrophysiology laboratory for catheter ablation of AF. These recordings were obtained prospectively as approved by the Institutional Review Board, and analyzed retrospectively for this study. Nine patients had documented clinical paroxysmal AF. Normal sinus rhythm was their baseline cardiac rhythm in the electrophysiology laboratory. Induction of AF was done via burst atrial pacing

Results

Examples of CFAE in persistent AF are shown in Fig. 1. The left superior, left inferior, right superior, and right inferior pulmonary vein recordings are given. In each trace there is little or no isoelectric interval, and the large deflections are time-varying. There is some periodicity evident in each of the signals, particularly in panels A, C and D. Note that only the first 1000 sample points, ~1 s, are provided so that the electrogram detail can be observed. The 1st and 2nd 8 s DMs for these

Summary

In this study the concept of a dominant morphology (DM) was introduced for CFAE signals. The DM is defined as the ensemble average of signal segments at the dominant frequency. The DM is representative of the basic shape of the CFAE from one electrical activation interval to the next. The DM may appear more or less like the original CFAE, depending on the periodicity and regularity of the CFAE deflections, and the degree to which the DF dominates the power spectrum. DMs were compared for 1st

Conclusions

The DM can be extracted and compared in paroxysmal and persistent CFAE. There is higher temporal variability in the DM of paroxysmal CFAE. There is also higher spatial variability in the DM of paroxysmal CFAE, although this does not rise to the level of significance (Table 3, Table 4). Extraction and analysis of the DM show that it is useful to quantitate electrogram morphology at the DF so that CFAE in paroxysmal versus persistent AF patients can be compared. The greater spatiotemporal

Conflict of interest statement

The authors have no conflicts of interest.

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