A 65 year old male with a history of hypertension, stage IV kidney disease on dialysis presents to the emergency department with dizziness and palpitations for 1 hour. He denies chest pains. His temperature is 37.0 C, blood pressure 80/40, heart rate 150, respirations 24, and oxygen saturation 85% on room air. Physical examination reveals pulmonary rales throughout his lung fields, elevated jugular venous pressure, a regular tachycardic rhythm without murmurs, and trace lower extremity pitting edema. Laboratory studies are normal. His ECG is below.
Which of the following is the most appropriate initial therapy?
A. Intravenous amiodarone
B. Intravenous beta-blockers
C. Intravenous calcium channel blockers
D. Emergent direct current cardioversion