Evaluating Sudden Onset of Palpitations

In Episode 41 of Med School Question of the Week for USMLE, Faustine Ramirez, MedSchoolCoach expert tutor, answers this medical school question: A 42-year-old woman presents to the emergency department with sudden onset of palpations. She has a history of anxiety and panic attacks, hypertension, and hypothyroidism. Her medications include sertraline, buspirone, lisinopril, and levothyroxine. She typically eats a varied diet but her oral intake has been limited as she recently completed a course of antibiotics for a community acquired pneumonia. She drinks 2-3 cups of coffee daily and occasionally uses recreational drugs. She is afebrile, heart rate is 170/min, respiratory rate is 18/min, and blood pressure is 142/84. She appears very anxious and is mildly diaphoretic. She is alert and oriented to person, place, and time. Pupils are 3 mm, equal, round, and reactive to light. Extremities are warm and well perfused and radial pulses are 2+ bilaterally. The remainder of the examination is unremarkable. EKG is performed (see in the video). What is the most likely cause of these findings?

• Hyperkalemia
• Panic attack
• Dehydration
• Levothyroxine
• Caffeine
• Cocaine
• Buspirone
• Amoxicillin
• Azithromycin