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Figure 2 Radial Strain Curves Assessed With Speckle-Tracking Analysis of a Representative Patient

The color-coded curves represent the 6 segments (light blue = septal; yellow = anteroseptal; red = anterior; green = lateral; purple = posterior; dark blue = inferior). (A) Before His bundle ablation and pacemaker implantation, there was no significant delay in time-to-peak radial strain among the 6 segments. (B) After 4 years of permanent right ventricular pacing, a marked heterogeneity in time-to-peak strain for the 6 segments was observed. A time difference >130 ms was present between the time-to-peak radial strain of the septal (arrow) and posterolateral (open arrow) segments. (C) In this patient, upgrade of the conventional pacemaker to a biventricular pacemaker was performed. More than 1 year after "upgrade," the radial strain curves revealed restoration of synchronous left ventricular activation, with no significant delay between the time-to-peak radial strain of the different segments.