Resolving Bipolar Electrogram Voltages During Atrial Fibrillation Using Omnipolar Mapping

Background: Low-voltage–guided substrate modification is an emerging strategy in atrial fibrillation (AF) ablation. A major limitation to contemporary bipolar electrogram (EGM) analysis in AF is the resultant lower peak-to-peak voltage (V pp ) from variations in wavefront direction relative to electrode orientation and from fractionation and collision events. We aim to compare bipole V pp with novel omnipolar peak-to-peak voltages (V max ) in sinus rhythm (SR) and AF. Methods and Results: A high-density fixed multielectrode plaque was placed on the epicardial surface of the left atrium in dogs. Horizontal and vertical orientation bipolar EGMs, followed by omnipolar EGMs, were obtained and compared in both SR and AF. Bipole orientation has significant impact on bipolar EGM voltages obtained during SR and AF. In SR, vertical values were on average 66±119% larger than horizontal ( P =0.004). In AF, vertical values were on average 31±96% larger than horizontal ( P =0.07). Omnipole V max values were 99.9±125% larger than both horizontal (99.9±125%; P <0.001) and vertical (41±78%; P <0.0001) in SR and larger than both horizontal (76±109%; P <0.001) and vertical (52±70%; P value <0.0001) in AF. Vector field analysis of AF wavefronts demonstrates that omnipolar EGMs can account for collision and fractionation and record EGM voltages unaffected by these events. Conclusions: Omnipolar EGMs can extract maximal voltages from AF signals which are not influenced by directional factors, collision or fractionation, compared with contemporary bipolar techniques.