Characterization of atrial propagation patterns can help understanding the mechanisms responsible for Atrial Fibrillation (AF) maintenance and guiding appropriate therapy, as in RF ablation. Omnipolar EGM (OP-EGM) is a recently proposed technique to characterize propagation in multi-electrode EGM data regardless of the direction of propagation. The aim of this work was to assess the accuracy of propagation parameters obtained with OP-EGM for different propagation patterns.
Epicardial EGM from a high-density MEA sensor during Sinus Rhythm (SR) and AF were used in this study. An 8x16 MEA was used with inter-electrode distance of 2 mm. We also used a uniform double-layer model of atrial tissue to simulate propagating patterns from a single focal point at different positions relative to the MEA. Conduction velocities (CV), angles (\theta) and voltages were obtained for each clique of four neighbor electrodes using OP-EGM method.
Analysis of simulated data showed good agreement with expected propagation patterns. When focus was placed at 30mm from the bottom of MEA, with simulated CV = 1 m/s, estimated CV (mean$\pm$std) was 1.05+/-0.005 m/s, with estimated \theta = 90.1º+/-2.7º. Estimated CV was 1.1+/-0.25 m/s when focus was at the corner of the MEA and 1.1+/-0.32 m/s when it was at the middle of the MEA. Larger errors appeared in cliques where the plane wave model does not hold. Analysis of clinical data showed good concordance with manual LAT maps, both in SR and AF. In SR, measured CV ranged from 0.49 to 2.12 m/s and the mean interbeat coefficient of variation for CV was of 0.12 (range:0.02-0.34). \theta ranged from 89.96º to 243º, with mean interbeat stdev of 9.5º (range:1.38º-59.6º).
OP-EGM allows to characterize atrial propagation patterns regardless of the relative direction with respect to the MEA. However, model compliance must be assessed to avoid large estimation errors in specific sites.