Figure 2. (A, B, C) ECG examples of sinus and paced P-wave duration. From top to bottom, ECG leads I, II, and III. In each example, sinus P-wave (left) duration (ms) and paced P-wave (right) duration (ms). Example A: Bipolar atrial pacing. Examples B and C: unipolar atrial pacing (note stimulus artifact; black arrow).