Mean LA velocity histograms for 21 patients in sinus rhythm (A) and 10 patients in AF (B) at the time of imaging. The mean velocity and the percent of velocity values greater than 0.2 m/s are marked each panel. The area of each histogram is normalized to unity. Panel (C) displays mean velocities from the top tertile of blood flow within the left atrium for the groups in panels (A-B). A signfican reduction (i.e. increased stasis) for persistant AF is evident.