what is the most likely cause of his condition

Question

A 56-year-old man with known coronary artery disease presents to the emergency department complaining of chest discomfort and palpitations for 2 hours. On arrival, the vital signs include blood pressure 122/76 mm Hg, heart rate 180/min, respiratory rate 22/min, temperature 37.0℃ (98.6℉), and blood oxygen saturation (SpO2) 98% on room air. A 12-lead electrocardiogram demonstrated ST-segment elevation in the anterolateral leads. The troponin level was 0.8 ng/mL (normal 0–0.4 ng/mL). The patient declined primary percutaneous intervention and was treated with antifibrinolytics in the coronary care unit. After 1 hour of treatment, the patient loses consciousness and the blood pressure falls to 60/40 mm Hg. Cardiac monitoring shows the electrocardiogram (ECG) pattern in lead 2 shown in the picture. What is the most likely cause of his condition?