A 68-year-old previously healthy man presents to the emergen…
A 68-year-old previously healthy man presents to the emergency department with a transient episode of confusion and difficulty speaking that occurred approximately one hour ago and lasted about 20 minutes. A non-contrast computed tomography scan of the brain shows no abnormalities. An electrocardiogram reveals new-onset atrial fibrillation with a ventricular rate of 96 beats/minute. Which of the following medications should be initiated?