Review Question - QID 210370

A 64-year-old woman presents to the emergency room with rapidly worsening chest pain and shortness of breath. She developed dull substernal chest pain 3 hours ago while watching a movie with her grandchildren. Her past medical history is notable for hyperlipidemia, hypertension, and knee osteoarthritis. She takes atorvastatin and lisinopril. She has a 15-pack-year smoking history and drinks 2-3 glasses of wine with dinner each night. She recently returned to the United States from a month-long trip to China. Her temperature is 98.6°F (37°C), blood pressure is 154/90 mmHg, pulse is 118/min, and respirations are 25/min. On exam, she appears uncomfortable but is able to respond to questions in complete sentences. A normal S1 and S2 are heard on cardiac auscultation. Her symptoms do not improve with sublingual nitroglycerin. Multiple troponin levels are taken and are normal. An electrocardiogram is shown in Figure A. What is the underlying cause of this patient’s condition?