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Figure 1 The 12-lead electrocardiogram of ventricular tachycardia (VT) (left panel), pace-mapping at site 5 (inferoseptal left ventricle) (middle panel), and pace-mapping at site 6-8 (basal lateral left ventricle [LV]) (right panel) in Patient 3 are shown. The pace-map at site 5 is a much closer match of VT with stimulus to QRS interval (S-QRS) <40 ms (no conduction delay) than the pace-map at site 6-8, which does not resemble VT but has a S-QRS delay of 65 ms. Entrainment mapping indicated that site 5 was an outer loop site and site 6-8 was an isthmus site in the re-entry circuit. Patient 3 in Figure 2 shows the S-QRS map and voltage map of this patient.