Which of the following is an example of a first-line antiarrhythmic for stable sustained VT?

• A. Lidocaine
• B. Adenosine
• C. Digoxin
• D. Epinephrine

Answer: (A)

For stable sustained ventricular tachycardia, you want a drug that rapidly suppresses the abnormal ventricular rhythm without causing hemodynamic instability. Lidocaine fits this role as a class Ib antiarrhythmic that blocks sodium channels and preferentially diminishes automaticity in ischemic or diseased ventricular tissue. This reduces ventricular ectopy and can terminate the rhythm quickly when given IV, making it a strong first-line option in this scenario.

Adenosine works by terminating AV nodal-dependent tachycardias, which are not VT, so it won’t reliably treat VT. Digoxin mainly affects atrial tachyarrhythmias and provides rate control or inotropy rather than rhythm control for VT. Epinephrine is reserved for resuscitation and unstable situations; in a patient who is stable, it’s not the rhythm-control agent of choice.