Which discriminant helps distinguish VT from AF with rapid ventricular response?

Which discriminant helps distinguish VT from AF with rapid ventricular response?

• A. Onset
• B. Stability
• C. QRS morphology
• D. Rate

Answer: (B)

Stability of how the rhythm behaves and the patient’s hemodynamic status is the key here. Ventricular tachycardia typically produces a steady, regular ventricular rhythm, even when the heart rate is high. In contrast, atrial fibrillation with rapid ventricular response yields an irregularly irregular ventricular rhythm because the atrial activity is chaotic and the ventricular response varies from beat to beat. So, looking at whether the rhythm is stable and regular versus irregular and unstable helps you tell VT apart from AF with RVR. The other features can be misleading: onset can occur abruptly in both, rate can be high in either, and QRS morphology can be variable or mimic VT if there is aberrant conduction.

Stability of how the rhythm behaves and the patient’s hemodynamic status is the key here. Ventricular tachycardia typically produces a steady, regular ventricular rhythm, even when the heart rate is high. In contrast, atrial fibrillation with rapid ventricular response yields an irregularly irregular ventricular rhythm because the atrial activity is chaotic and the ventricular response varies from beat to beat. So, looking at whether the rhythm is stable and regular versus irregular and unstable helps you tell VT apart from AF with RVR. The other features can be misleading: onset can occur abruptly in both, rate can be high in either, and QRS morphology can be variable or mimic VT if there is aberrant conduction.