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Figure 1 VT Exit Site Localization

Shown, for 4 patients (AP, PB, AP, and LS), are maps of the 15 endocardial regions initially sampled in VT at electrophysiologic study and those more thoroughly sampled (circled). Shaded circles represent regions of earliest activation, sometimes multiple. X marks the site of earliest phase angle, the scintigraphic VT exit site. Electrophysiologic and scintigraphic exit disagreed only in AP, upper left, where phase analysis identified an adjacent segment. See Online Video 1. VT = ventricular tachycardia.