This patient's metoprolol should be withheld for 48 hours before stress testing. In this intermediate-probability patient with a normal electrocardiogram, exercise stress testing is appropriate. Exercise stress is preferred to pharmacologic stressors because it provides a gauge of functional capacity and a contextual understanding of symptoms, and it records hemodynamic response to exercise. The sensitivity of the study to detect obstructive coronary artery disease (CAD) is lowered, however, if patients are taking certain medications. β-Blockers and nondihydropyridine calcium channel blockers can blunt the maximal heart rate that can be achieved with exercise and may limit a patient's ability to reach 85% of the maximal predicted heart rate. However, dihydropyridine calcium channel blockers do not need to be withheld prior to testing. Similarly, digoxin can limit the maximal heart rate and should be withheld. Nitrates are effective antianginal agents but may minimize the ischemic response on stress testing; therefore, they should also be withheld. If, however, a patient has known CAD and the goal of testing is to determine whether symptoms are related to ischemia or to assess adequacy of antianginal therapy, there is no need to stop any of the medications.

There is no evidence that ACE inhibitors, such as lisinopril, or angiotensin receptor blockers alter the sensitivity of exercise stress testing in the diagnosis of CAD, and these agents do not need to be discontinued before testing. For this patient on several medications for hypertension, an appropriate strategy would be to continue hydrochlorothiazide and lisinopril and discontinue metoprolol.