Final answer:
Adenosine is the preferred intervention for terminating narrow-complex tachycardias that are symptomatic and supraventricular in origin (SVT).
Step-by-step explanation:
The preferred intervention for terminating narrow-complex tachycardias that are symptomatic (but stable) and supraventricular in origin (SVT) is adenosine.
Adenosine is commonly used to convert SVT to a normal sinus rhythm. It works by temporarily blocking the AV node and interrupting the reentry pathway responsible for SVT. Adenosine is administered intravenously and has a very short half-life, which allows the heart's electrical system to reset.
Other mentioned drugs like epinephrine, amiodarone, and atropine may be used for other cardiac conditions but are not the preferred interventions for terminating narrow-complex, stable, supraventricular tachycardias.