A 56-Year-Old Man Comes to the Emergency Department Due to Palpitations

question 368

Multiple Choice

A 56-year-old man comes to the emergency department due to palpitations and lightheadedness over the last 2 hours.  He has a history of hypertension but no other cardiac conditions and never before had similar symptoms.  The patient drinks 1 to 2 alcoholic beverages daily but does not smoke cigarettes or use illicit drugs.  Blood pressure is 132/76 mm Hg and pulse is 116/min and irregular.  Cardiopulmonary examination is normal, except for tachycardia.  Resting ECG shows atrial fibrillation.  The patient undergoes transesophageal echocardiography, which reveals normal cardiac anatomy and no intracardiac thrombi.  Electrical cardioversion is performed.  After the intervention, sinus rhythm is restored, and amiodarone therapy is begun to maintain normal sinus rhythm.  Which of the following cardiac electrophysiologic changes are most likely to occur in this patient due to the medication?

• A)A
• B)B
• C)C
• D)D