Identify the hallmark feature of ventricular tachycardia (VT).

The hallmark feature of ventricular tachycardia (VT) is the presence of three or more consecutive ventricular beats at a rate greater than 100 beats per minute. VT typically arises from abnormal electrical activity in the ventricles and can lead to a drastically elevated heart rate, which is often sustained, potentially resulting in hemodynamic instability.

In VT, the ventricular beats are originating in the ventricles themselves, causing a rapid heart rhythm that can have significant clinical implications, especially if it progresses to more severe forms of tachycardia or leads to ventricular fibrillation. Identifying this characteristic is crucial for diagnosis and subsequent treatment, as VT can be life-threatening.

Other options do not accurately describe VT; for instance, less than three consecutive beats cannot constitute tachycardia, a normal heart rate with P waves suggests a different rhythm altogether (such as sinus rhythm), and frequent premature atrial contractions pertain to atrial activity, not ventricular events. Consequently, the definition that best represents the essence of ventricular tachycardia is the presence of three or more consecutive ventricular beats at an elevated heart rate.