Review Question - QID 212711

A 25-year-old woman is brought to the emergency department by her boyfriend after passing out at the movies. The boyfriend reports that they were at the movie theater when his girlfriend began complaining that “my heart is going to pop out of my chest.” Shortly after, her head slumped forward and she was unresponsive for about 10-15 seconds. The patient confirms this history and endorses feeling anxious and lightheaded before the episode. She denies sensory or motor changes, incontinence, trauma to the head, or seizure activities. She has had episodes of heart palpitations before but attributes it to her anxiety. A physical examination is unremarkable except for tachycardia and slightly enlarged thyroid. An electrocardiograph (ECG) is obtained (Figure A). What is the most likely explanation for this patient’s condition?