A swinging rhythm

A previously healthy 45-year-old man was referred to the emergency department post–cardiopulmonary resuscitation after documented ventricular fibrillation (VF). His blood pressure was 80/40 mm Hg. There was no family history of sudden death. His family noted that he drank Chinese steamed herbal medication several hours before admission. He complained of nausea, vomiting, and numbness of the face and limbs, followed by a sudden collapse due to VF. A 12-lead electrocardiogram (ECG) was performed (Figure 1). What are the notable ECG findings? What is the most likely cause for the cardiac arrest?