Supraventricular arrhythmias: Pathology review

A 73-year-old female presents to the emergency department with shortness of breath. She is concerned her “COPD is flaring up.” Past medical history is notable for hypertension, chronic obstructive pulmonary disease, and type II diabetes mellitus. She has been smoking one pack of cigarettes per day for twenty years. Temperature is 37.0°C (98.6°F), pulse is 136/min, respirations are 22/min, blood pressure is 104/72 mmHg, and oxygen saturation is 92% on room air. The patient is currently speaking in three to four word sentences and demonstrates increased work of breathing. There are bilateral rales throughout the lung fields, and the electrocardiogram from triage is shown below:  


Based on this patient's electrocardiogram, which of the following is the most likely diagnosis?