What is the first-line treatment for stable supraventricular tachycardia (SVT)?

The first-line treatment for stable supraventricular tachycardia (SVT) is to initiate vagal maneuvers. These maneuvers, which include techniques like the Valsalva maneuver or carotid sinus massage, aim to stimulate the vagus nerve and increase parasympathetic tone. This can help to slow down the heart rate and potentially terminate the arrhythmia by interrupting the reentrant circuit responsible for SVT.

Vagal maneuvers are a non-invasive approach, making them appropriate for stable patients who are not experiencing severe symptoms or hemodynamic instability. If these maneuvers are unsuccessful in resolving the tachycardia, other treatments like adenosine or cardioversion may be considered based on the patient's condition and response. However, in the context of stable SVT, initiating vagal maneuvers is the preferred first step in management.