This plateau occurs between the P wave and the QRS complex. If the ST segment appears below the level of the PQ junction, a doctor will likely confirm that the person has an ST segment depression.

The P waves are positive in leads I, II, aVF, and V4-V6; hence, this is a sinus tachycardia. However, there is AV dissociation: The P waves are dissociated from the QRS complexes and the PR ...