A 65-year-old man arrives at the emergency department complaining of substernal chest pain and intermittent palpitations that began this morning. The patient has a history of coronary artery disease and stable angina, both of which are medically managed. He takes metoprolol at high doses, atorvastatin, and aspirin at low doses. The patient reports that he has been traveling for the past week and that his medications ran out two days ago. The temperature is 37 degrees Celsius (98.6 degrees Fahrenheit), the blood pressure is 148/82 mm Hg, and the pulse rate is 112/min. The electrocardiogram shows sinus tachycardia with a 1-mm ST segment depression in the lateral leads. Which of the following is most likely responsible for this patient's presentation?

Question

Quizplus · Accepted Answer

Eductional Objective: Cells can adjust their sensitivity to a prolonged environmental stimulus by upregulating or downregulating surface membrane receptors. Prolonged beta blockade increases beta-adrenergic receptor upregulation and sensitivity to circulating catecholamines, resulting in an enhanced beta-adrenergic response upon abrupt beta blocker discontinuation (ie, beta blocker withdrawal syndrome).

A 65-Year-Old Man Arrives at the Emergency Department Complaining of Substernal