For patients without a history of coronary artery disease, medications including beta-blockers, calcium channel blockers (amlodipine), and nitrates should be stopped 48 hours before undergoing a cardiac stress test, as these agents affect the accuracy of stress testing.
Such medications may cause a false negative by masking ischemic changes on the electrocardiogram or stress test imaging. Additionally, they may cause a false positive result by creating artificial ischemic changes on the electrocardiogram. Stopping these agents 48 hours prior to the stress test allows for 4-5 half-lives to pass, thereby reversing the hemodynamic effects of these medications. In contrast to the above patient, if a patient has a known history of coronary artery disease, their antianginal medications (nitrates, beta-blockers, and calcium channel blockers) should be continued to evaluate the efficacy of the patient's treatment regimen with exertion. Indications for stress testing can include pre-operative assessment, identification of the extent/existence of coronary artery disease, evaluation of the efficacy of current cardiac treatment, and identification of appropriate and safe levels of exercise.
Fletcher et al. review the indications and utility of cardiac stress testing. For asymptomatic men older than 45 who have certain risk factors (hyperlipidemia, hypertension, smoking, diabetes mellitus, history of myocardial infarction or sudden death in a young, first-degree family member), cardiac stress testing can provide insightful prognostic information for a patient's risk of a future cardiac event. Guidelines recommend that asymptomatic patients meeting the risk factor criteria mentioned previously should undergo a stress test before initiating a new exercise regimen.
Makaryus et al. discuss stress myocardial perfusion imaging as a cardiac risk-assessment tool for elderly preoperative patients. They find that the sensitivity of stress testing for detecting coronary artery disease increases with age; however, in contrast, the specificity of this test declines with increasing age. They hypothesize that this is due to the increased prevalence and greater severity of coronary artery disease in elderly patients.
Illustration A summarizes contraindications to cardiac stress testing. Illustration B shows the different types of cardiac stress testing and evaluation methods available.
Answer 1: Caffeine interferes with the results of stress testing; however, it is only necessary to withhold consumption for 24 hours before the stress test.
Answer 2: Aspirin does not affect the quality of the results obtained from stress testing, and there is no need to hold this medication prior to the test.
Answer 4: Increasing metformin and skipping a meal may trigger a hypoglycemic episode, particularly with the amount of exertion involved in an exercise stress test. Patients should be instructed to avoid eating within 4 hours prior to the test; however, their diabetes medication should be taken after, not before, the test.
Answer 5: Although smoking cessation should be stressed at every patient encounter, for the purposes of maintaining the accuracy of the stress test, cigarette smoking should only be stopped for the day of the test.
Fletcher GF, Mills WC, Taylor WC. Update on exercise stress testing. Am Fam Physician. 2006 Nov 15;74(10):1749-54.
PMID:17137006 (Link to Abstract)
Makaryus AN, Diamond JA. Nuclear stress testing in elderly patients: a review of its use in the assessment of cardiac risk, particularly in patients undergoing preoperative risk assessment. Drugs Aging. 2007;24(6):467-79.
PMID:17571912 (Link to Abstract)