Treatment Options for Vasovagal Syncope: A Clinical Dilemma

An otherwise healthy 25-year-old woman presents to the general cardiology clinic as a referral for recurrent transient loss of consciousness. For the prior few years, she has had occasional spells during which she collapsed but with some warning. One spell occurred after taking a hot shower, one after she hurt her wrist during a soccer game, and one during a particularly stressful fight with her boyfriend. Before the episodes, she endorses a prodrome of diaphoresis, nausea, and weakness. The episodes tend to occur around menses. There are no preceding palpitations, dyspnea, or chest pain. Her family members, who have witnessed some episodes, have not noticed any seizure-like activity during the spells. She recovers back to baseline neurologic function within a few minutes. On one recent occasion, she collapsed after prolonged standing, causing her right shoulder to dislocate from falling. She has no family history of cardiac disease or sudden cardiac death. She denies tobacco, alcohol, or illicit drug use.

On examination, her blood pressure (BP) is 110/80 mm Hg, heart rate (HR) is 80 bpm, oxygen saturation is 98% on room air, and temperature is 37°C. Orthostatic vital signs are performed and her BP decreases to 100/75 mm Hg with HR 89 bpm upon standing for 3 min. A complete physical examination is unremarkable. Pregnancy testing is negative. Her electrocardiogram shows normal sinus rhythm without abnormality. Transthoracic echocardiography is unremarkable. Tilt-table testing is performed and shows a drop in BP from 110 mm Hg systolic to 95 mm Hg with HR that initially goes from 60 to 86 bpm while upright and then falls back to 60 bpm; this does not reproduce her symptoms.

A 30-day event monitor is ordered but is unremarkable. Therefore, she undergoes an implantable loop recorder (ILR) implantation. At 6 months, she has an episode of collapse associated with the following rhythm disturbance during an extremely stressful time (Figure 1).

Figure 1

Figure 1

Which one of the following is the best next step in management?

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