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Figure 5 Mechanical activation maps in the "bull's-eye" projection from representative heart failure patients before and after cardiac resynchronization therapy (CRT). (A) A patient with LBBB. (B) A patient who previously received a right ventricular pacer (RV) for bradycardia and was RV paced at baseline. Time to peak systolic strain was color coded with lines representing isochrones of mechanical activation times at 50-ms intervals. The X indicates sites of lead placement, and the arrow indicates the direction of the propagating mechanical activation. Time to peak strain of sites adjacent to anterolateral (AL P) and posteromedial (PM P) papillary muscles are shown. A decrease in interpapillary muscle time delay was associated with decreased mitral regurgitation (MR).