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Figure 4 QRS duration and notching. (A) Total duration of the QRS complex of mitral annulus (MA) ventricular tachycardia (VT)/premature ventricular contraction (PVC). In anterolateral (AL) and posterior (P) MAVT/PVC, the QRS duration was significantly longer than in the posteroseptal (PS)-MAVT/PVC. The QRS duration was >140 ms in all AL-MAVT/PVC and Pos-MAVT/PVC, whereas it was <140 ms in all PS-MAVT/PVC. (B) Twelve-lead ECGs obtained during pacing from the AL (a), P (b), and PS (c) portion of the MA. Arrows indicate "notching" of the late phase of the QRS complex in the inferior leads.