A 19-year-old white male presents to the emergency department (ED) in Connecticut after an episode of shortness of breath and syncope while at home. He reports having experienced recurrent episodes of palpitations and fatigue in the week before presentation. Yesterday, the patient sought medical attention for these symptoms at his pediatrician’s office. An electrocardiogram (ECG) was performed, but it was normal; the patient was sent home wearing a Holter monitor (also known as an ambulatory electrocardiography device). Today, while mowing the lawn, the patient again felt a sudden onset of palpitations, accompanied by shortness of breath and light-headedness. He went inside the house, where he suddenly “passed out” (according to the patient’s girlfriend). The girlfriend also states that he was unresponsive for a couple of minutes and that the patient exhibited no seizurelike activity or incontinence. She noted that he was “pretty much himself” once he regained consciousness. He was then brought by ambulance to the ED; a rhythm strip was acquired en route (see top image). Prophylactic transcutaneous pacer pads were placed by the emergency medical services (EMS) team.
In the ED, the patient describes his palpitations as irregular, forceful beats, with a sensation of a racing heart. They occur spontaneously, without any clear inciting factors. He denies having any chest pain or shortness of breath at the time of questioning in the ED. He has not experienced any similar events prior to these, and he is usually active and athletic. The patient denies having any recent fevers, upper respiratory infections, cough, or sore throat. He denies having any recent headaches, neck stiffness, tinnitus, vertigo, or focal neurologic deficits. He also denies experiencing any bleeding (eg, no hematochezia or melena). The patient has been eating a regular diet and has not had any recent weight loss. His past medical history is only significant for a cervical spine fracture secondary to a diving accident that occurred 3 years ago. He has no residual deficits or physical limitations. The patient is otherwise healthy, with no known cardiac, neurologic, or pulmonary disease. He has no known family history of sudden death or premature cardiac disease. He does not take any regular medications, and he denies any drug abuse, tobacco use, or alcohol consumption. The Holter monitor had been removed before he began to mow the lawn; therefore, no results were available to ED staff.
On physical examination, the patient appears to be in no acute distress, but he is noted to have moderate anxiety. He is nontoxic-appearing and alert. His vital signs include a temperature of 96.7°F (35.9°C), a pulse rate between 40-120 bpm, a respiratory rate of 16 breaths/min, and a blood pressure of 102/46 mm Hg. His oxygen saturation is 96% while breathing room air. His head and neck examination is unremarkable. No jugular venous distention or carotid bruits are noted. His lungs are clear to auscultation bilaterally. His cardiac examination reveals an irregular, tachycardic rhythm. There is no discernible murmur with or without Valsalva maneuvers or hand clenching. His abdomen is soft, nontender, and nondistended. No clubbing, cyanosis, or edema is noted in his extremities. His neurologic examination is normal. On skin examination, multiple, bilateral macular erythematous lesions with large central pallor are noted on his thighs.
An ECG is obtained (see bottom image). What is the diagnosis? How would you approach this patient’s treatment?