A 15-year-old South Asian male patient with no significant medical history presented with recurrent presyncope and syncope to the emergency department for the previous week. Syncope would occur after prodromal presyncope with faintness and lightheadedness and would be brief, often lasting a few seconds, without any epileptic features. He reported, on average, several episodes of each daily, with the latter occurring as many as 10 times per day, each lasting a few seconds in duration. He did not report any recent antecedent viral infection with COVID-19 as of the onset of the pandemic, head trauma, medication use, or travel history. The patient also refuted any lifestyle modification with respect to dietary intake and physical activity and routinely performed his usual activities of daily living. Prior to the onset of symptoms, he was physically active and regularly participated in vigorous sporting activities such as football (soccer) at his local high school. Two weeks earlier, he received the Pfizer-BioNTech COVID-19 vaccine booster with the initial two-dose sequence eight months prior. Additionally, he was also vaccinated with the Gardasil  human papillomavirus (HPV) vaccine three months previously. COVID-19 polymerase chain reaction testing was negative upon admission.
His vital signs on presentation revealed a blood pressure of 105/53 mmHg and a regular heart rate of 107 beats per minute, with pulse oximetry of 100% on room air. He was afebrile with a body mass index of 19.3 kg/m2. His orthostatic vital signs were normal. On physical examination, he was alert and oriented without any neurological deficits. His heart sounds were normal, with vesicular breath sounds on auscultation of the lung fields. There was no peripheral edema. Further advanced testing included a two-dimensional transthoracic echocardiogram, computed tomography of the brain, magnetic resonance imaging and angiography of the brain, and 24-hour ambulatory electroencephalogram, all of which were normal. Inpatient telemetry revealed sinus tachycardia during the syncopal episodes (Figure 1). Tilt table testing was not performed due to its unavailability in our setting.
During his ensuing three-day hospitalization, the patient was initiated on fludrocortisone 0.1 mg every eight hours and ivabradine 2.5 mg every 12 hours. He was also advised on lifestyle modification with respect to increasing sodium and fluid intake, avoiding sun exposure to prevent dehydration, and following a moderate-intensity exercise regimen. His constellation of symptoms, including exercise tolerance and fatigue, gradually abated to where he experienced decreasing episodes of syncope on consecutive days, and on the penultimate day and day of discharge, he did not experience any. At one-month post-discharge, the patient's medical regimen was de-escalated to fludrocortisone twice daily as monotherapy, and there were no other serious adverse events.