Q. A 51-year-old male comes to the emergency department because of typical chest pain for the one-hour duration. The patient's medical history is significant for diabetes, hypertension, and chronic obstructive pulmonary disease. He has smoked 30 cigarettes/day for the last 20 years. His ECG is shown below. A short time later, the patient vomits twice, becomes unresponsive, and goes into cardiac arrest. Which of the following is the most likely cause of cardiac arrest in this patient?