Review Question - QID 214315

A 65-year-old man presents to the emergency department with a sensation of palpitations. He states this feeling had started 2 days ago and has been worsening. The patient has a past medical history of hypertension, diabetes, peripheral vascular disease, and chronic obstructive pulmonary disease. He recently stayed at a cabin in the mountains and went on daily hikes. A review of systems is notable for abdominal pain and nausea and vomiting during this time frame. He also feels like he sees a glare around lights at night that is new. His temperature is 98.1°F (36.7°C), blood pressure is 112/73 mmHg, pulse is 122/min, respirations are 16/min, and oxygen saturation is 98% on room air. An ECG is performed as seen in Figure A. Which of the following is the most likely etiology of this patient’s symptoms?