A 56-year-old woman with no known structural heart disease (SHD) presents for follow-up with her cardiologist for "racing heart" episodes that have become more disruptive over the past year. She reports sudden-onset palpitations occurring two to three times per month without recognizable provocation, lasting 20-40 min, often associated with lightheadedness, chest discomfort, and anxiety. Between episodes, she feels well. She has presented to the ED four times in the past 12 months because of similar events. On two occasions, intravenous (IV) adenosine was required; on the most recent visit, IV diltiazem was administered, with rapid termination of the tachycardia. She has tried vagal maneuvers at home with inconsistent success. Her smartwatch tracings during her symptoms show a regular narrow-complex tachycardia at 180-190 bpm with abrupt onset and termination. Her medications include lisinopril 10 mg daily for well-controlled hypertension and sertraline 50 mg daily for depression. She does not smoke and drinks alcohol socially. In the clinic today, she is free of symptoms.

Her vital signs include blood pressure 124/76 mm Hg, heart rate 72 bpm, and oxygen saturation 98% on room air. Physical examination findings are unremarkable.

A 12‑lead electrocardiogram in sinus rhythm shows a normal PR interval, narrow QRS complexes, and no evidence of pre-excitation. An echocardiogram demonstrates normal biventricular function and no significant valvular disease. Laboratory study results, including thyroid function values, are within the reference ranges.

She is frustrated by her recurrent ED visits and worried about the impact of these episodes on her work and quality of life. She is interested in options that would allow her to better manage episodes outside of the hospital. The cardiologist confirms that her symptoms and wearable tracings are consistent with an atrioventricular nodal re-entrant tachycardia form of paroxysmal supraventricular tachycardia (PSVT).