A 72-year-old man comes to the physician because of a 2-month history of intermittent retrosternal chest pain and tightness on exertion. He has type 2 diabetes mellitus, osteoarthritis of the right hip, and hypertension. Current medications include insulin, ibuprofen, enalapril, and hydrochlorothiazide. Vital signs are within normal limits. His troponin level is within the reference range. He undergoes dobutamine infusion with simultaneous cardiac imaging. The following is seen:Before infusion: normal left ventricular contractility, ejection fraction 60%During infusion: decreased apical contractility, ejection fraction 45%Five minutes after infusion: normal left ventricular contractility, ejection fraction 60%Which of the following best explains the observed findings?

Question

A 72-year-old man comes to the physician because of a 2-month history of intermittent retrosternal chest pain and tightness on exertion. He has type 2 diabetes mellitus, osteoarthritis of the right hip, and hypertension. Current medications include insulin, ibuprofen, enalapril, and hydrochlorothiazide. Vital signs are within normal limits. His troponin level is within the reference range.  He undergoes dobutamine infusion with simultaneous cardiac imaging.  The following is seen:Before infusion: normal left ventricular contractility, ejection fraction 60%During infusion: decreased apical contractility, ejection fraction 45%Five minutes after infusion: normal left ventricular contractility, ejection fraction 60%Which of the following best explains the observed findings?

Quizplus · Accepted Answer

Eductional Objective: Stable angina results from fixed coronary artery stenosis that limits blood flow to downstream myocardium, preventing the myocardial oxygen supply from increasing during exertion.  Dobutamine mimics the effects of exercise and increases myocardial oxygen demand; it can be used during stress testing to provoke areas of ischemic myocardium, which can be recognized on imaging by a localized and transient decrease in contractility (ie, wall motion defect).

A 72-Year-Old Man Comes to the Physician Because of a 2-Month