The disparities in the electrogram voltage measurement during atrial fibrillation and sinus rhythm.

INTRODUCTION: The peak electrogram voltage is a typical metric applied at each site for voltage mapping. However, the peak amplitude depends on the direction and complexity of the wavefront propagation. The root-mean-square (RMS) measure of the amplitude is a temporal integral that represents the steady-state value. The objective of this study was to investigate the disparities between the electrogram voltage during SR and AF by using 2 recording modalities: the conventional peak voltage and an RMS measurement.

METHODS AND RESULTS: This study enrolled 20 patients (age = 59 +/- 13) with paroxysmal AF undergoing catheter ablation guided by Ensite array. The unipolar electrogram voltage during SR and AF (7 seconds in duration) was obtained from the same sites, and labeled by the 3-dimensional (3D) geometry. Overall 1,200 electrograms were analyzed from equally distributed mapping sites in the left atrium. A point-by-point comparison of the unipolar peak negative voltage (PNV) showed less agreement (Bland and Altman test: 10.4% outside 2 standard deviations, and intraclass correlation coefficient [ICC]= 0.64). The RMS voltage demonstrated agreement between SR and AF for all sites (BA test: 5.9% of the sites, and the ICC = 0.81). The probability of predicting a low-voltage during AF using the voltage during SR was significantly lower when using the PNV measurement compared to that when using the RMS voltage (15% vs 61%, P < 0.05).

CONCLUSION: The peak electrogram unipolar voltage during AF did not represent the voltage during SR. The RMS amplitude may be an alternative metric for voltage mapping to characterize the myocardial substrate.