Differences in continuous spectra of fractionated electrograms in paroxysmal versus persistent atrial fibrillation

Quantitative measurements are helpful to discern fractionated electrograms in paroxysmal and persistent atrial fibrillation (AF), and may be useful to detect optimal ablation sites. However, electrical activation events can be transient, leading to erroneous estimates of electrogram properties. Measurement of continuous changes in electrogram frequency content may improve analysis.

Fractionated local electrograms from 10 paroxysmal and 10 persistent AF patients were acquired from outside the pulmonary vein ostia and left atrial free wall using the distal bipolar ablation catheter electrode, and analyzed over continuous 16 second intervals. A New Spectral Estimator (NSE) updated the frequency spectrum and spectral parameters once per millisecond. The tallest spectral peak (dominant frequency or DF) was determined. Statistical tests of variability were used to determine significant differences between paroxysmal and persistent AF.

Changes in the value of the DF over 16 seconds were caused by transient drifts in the frequency of the dominant peak, or by changes in which peak had the highest amplitude. The continuous DF and the spectral profile parameters were more highly variable in paroxysmal as compared with persistent AF patients (p<0.001). There was found to be a gradient from high to low variability of DF in paroxysmal AF, from the left superior pulmonary vein antrum to the left atrial free wall.

The results suggest that atrial electrical activation becomes more stable and focused at a narrow frequency range in persistent as compared to paroxysmal AF. The NSE implemented for continuous update of spectral parameters, enables a rapid characterization of fractionated electrograms with high time-frequency resolution and low computational cost.