Stress tests: How to make a calculated choice

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Applied Evidence

Stress tests: How to make a calculated choice

J Fam Pract. 2007 April;56(4):287-E1

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References

1. Snow V, Barry P, Fihn SD, et al. Evaluation of primary care patients with chronic stable angina: guidelines from the American College of Physicians. Ann Intern Med 2004;141:57-64.

2. Diamond GA. A clinically relevant classification of chest discomfort. J Am Coll Cardiol 1983;1:574-575.

3. Morise AP. Are the American College of Cardiology/American Heart Association guidelines for exercise testing for suspected coronary artery disease correct? Chest 2000;118:535-541.

4. Shaw LJ, Peterson ED, Shaw LK, et al. Use of a prognostic treadmill score in identifying diagnostic coronary disease subgroups. Circulation 1998;98:1622-1630.

5. Gibbons RJ, Balady GJ, Bricker JT, et al. ACC/AHA 2002 guideline update for exercise testing: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Committee on Exercise Testing). 2002. Available at: www.acc.org/qualityandscience/clinical/guidelines/exercise/exercise_clean.pdf. Accessed on March 6, 2007.

6. Gibbons RJ, Chatterjee K, Daley J, et al. ACC/AHA/ACP-ASIM guidelines for the management of patients with chronic stable angina: A report of the American College of Cardiology/American Heart Association task force on practice guidelines (Committee on Management of Patients with Chronic Stable Angina). J Am Coll Cardiol 1999;33:2092-2197.

7. Pellikka PA, Sarano ME, Nishimura RA, et al. Outcome of 622 adults with asymptomatic, hemodynamically significant aortic stenosis during prolonged follow-up. Circulation 2005;111:3290-3295.

8. Lewis JF, McGorray S, Lin L, et al. Exercise treadmill testing using a modified exercise protocol in women with suspected myocardial ischemia: Findings from the national heart, lung and blood institute-sponsored women’s ischemia syndrome evaluation (WISE). Am Heart J 2005;149:527-533.

9. Klocke FJ, Baird MG, Lorell BH, et al. ACC/AHA/ASNC guidelines for the clinical use of cardiac radionuclide imaging—executive summary: A report of the American College of Cardiology/American Heart Association task force on practice guidelines (ACC/AHA/ASNC committee to revise the 1995 guidelines for the clinical use of cardiac radionuclide imaging). J Am Coll Cardiol 2003;42:1318-1333.

10. Lee TH, Boucher CA. Clinical practice. noninvasive tests in patients with stable coronary artery disease. N Engl J Med 2001;344:1840-1845.

11. Myers J, Voodi L, Umann T, Froelicher VF. A survey of exercise testing: Methods, utilization, interpretation, and safety in the VAHCS. J Cardiopulm Rehabil 2000;20:251-258.

12. Ashley EA, Myers J, Froelicher V. Exercise testing in clinical medicine. Lancet 2000;356:1592-1597.

13. Cosmai EM, Heller GV. The clinical importance of electrocardiographic changes during pharmacologic stress testing with radionuclide myocardial perfusion imaging. J Nucl Cardiol 2005;12:466-472.

14. Kwok JM, Miller TD, Hodge DO, Gibbons RJ. Prognostic value of the duke treadmill score in the elderly. J Am Coll Cardiol 2002;39:1475-1481.

15. Morise AP, Olson MB, Merz NB, et al. Validation of the accuracy of pretest and exercise test scores in women with a low prevalence of coronary disease. The NHLBI-sponsored Women’s Ischemia Syndrome Evaluation (WISE) Study. Am Heart J 2004;147:1085-1092.

16. InfoRetriever [web site] Clinical Rules and Calculators (2007). InfoRetriever Search Results, Exercise Testing, Diagnostic Tests, Chest Pain. Available at: www.infopoems.com/irsearch/display_article.cfm?resource=D&article=34. Accessed on January 26, 2007.

17. Morrow K, Morris CK, Froelicher VF, et al. Prediction of cardiovascular death in men undergoing noninvasive evaluation for coronary artery disease. Ann Intern Med 1993;118:689-695.

18. Kwok JF, Christian TE. Effective use of the exercise stress test to detect and predict coronary artery disease. Emerg Med 2001;33:12-22.Available at: www.emedmag.com/html/pre/fea/features/051501.asp. Accessed on March 7, 2007.

On examination, document murmurs, rhythm abnormalities, vascular bruits, and abnormal pulses. Limit laboratory studies to recent cardiac damage screening if indicated. Screen with a resting ECG for arrhythmias, conduction abnormalities or preexisting cardiac damage. ST-segment (≥1 mm) and T-wave changes such as inversions secondary to strain or old injury or conduction abnormalities such as bundle branch blocks and prolonged QT interval may obscure exercise treadmill testing findings. Consider spirometry for patients with asthma or chronic lung disease.

A guide to sensitivity, specificity, and likelihood ratios for stress tests

Exercise treadmill testing

Sensitivity varies from 45% to 67% and specificity 72% to 90% with operator and patient variables.⁶ An abnormal test in a man at a heart rate of 85% of predicted maximum for age has a sensitivity of about 65% and a specificity of 85% for CAD. In women, one meta-analysis demonstrated a sensitivity of only 61% and a specificity of only 70%.⁸

PSMI

Pharmacologic stress myocardial imaging is similar to exercise treadmill testing. Dipyridamole and adenosine PSMI with thallium T1 201 or technetium Tc 99m have a similar sensitivity of 90%, and specificity of 70% for detection of CAD.⁶

Echocardiography

Overall sensitivity for exercise echocardiography was about 85% and for dobutamine stress echocardiography 82%. Dobutamine has a higher sensitivity than vasodilator echocardiography.⁶

Likelihood ratios (LR) for exercise treadmill testing and PSMI

Based on a review of coronary artery disease with chest pain as the symptom and a reference standard of a coronary angiogram with >70% narrowing of one or more arteries, or >50% left main, the LR varies for sex and for each different study. The positive LR (LR+) for exercise treadmill testing is 3.00 for men and 2.00 for women. The negative LR (LR–) for exercise treadmill testing is 0.650 for men and 0.560 for women. LR+ for exercise treadmill testing with thallium imaging is 5.9 (generally), but 2.20 for women; LR–is 0.200 and is 0.340 for women. Dipyridamole PSMI, LR+ is 3.30 and LR- is 0.180.¹⁶

The decisive factors

Absolute contraindications to exercise treadmill testing include recent MI; significant aortic stenosis,⁷ and weight exceeding equipment capacity. Relative contraindications to exercise treadmill testing (which can be superseded if the benefits of exercise outweigh the risks) include: hypertension (systolic >200 mm Hg/diastolic >110 mm Hg),⁵ left main coronary stenosis and stenotic valvular disease. (For more on “Contraindications to exercise testing,” see TABLE 2.)

The role of imaging: Important, yes—routine, no

An important element of stress testing is, of course, the imaging method(s) that will be used. The options include myocardial perfusion imaging with thallium Tl 201 or technetium Tc 99m, and echocardiography.

FAST TRACK

The Bruce exercise treadmill testing protocol may not be appropriate for the elderly; a ramp method may be better

Indications for myocardial perfusion imaging with exercise treadmill testing are a high pretest probability for CAD, an abnormal baseline ECG such as left bundle branch block, previous myocardial damage or coronary revascularization, or a previous equivocal or unexpected exercise ECG result. In women with an intermediate pretest probability for CAD, the sensitivity and specificity of an exercise treadmill testing is less than in men, which suggests that nuclear imaging would improve this test.⁸ There is, however, insufficient data to justify initial routine stress imaging tests in women.¹

TABLE 2
Contraindications to exercise testing

ABSOLUTE
Acute myocardial infarction (within 2 days) High-risk unstable angina Uncontrolled cardiac arrhythmias causing symptoms or hemodynamic compromise Symptomatic severe aortic stenosis Uncontrolled symptomatic heart failure Acute pulmonary embolus or pulmonary infarction Acute myocarditis or pericarditis Acute aortic dissection
RELATIVE CONTRAINDICATIONS (CAN BE SUPERSEDED IF THE BENEFITS OF EXERCISE OUTWEIGH THE RISKS)
Left main coronary stenosis Moderate stenotic valvular heart disease Electrolyte abnormalities Severe arterial hypertension (in the absence of definitive evidence, the committee suggests systolic blood pressure of >200 mm Hg or diastolic blood pressure of >110 mm Hg) Hypertrophic cardiomyopathy and other forms of outflow tract obstruction Mental or physical impairment leading to inability to exercise adequately High-degree atrioventricular block
Source: Gibbons RJ, Balady GJ, Bricker JT, et al. ACC/AHA 2002 guideline update for exercise testing: A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Committee on Exercise Testing). 2002. Available at: www.acc.org/qualityandscience/clinical/guidelines/exercise/exercise_clean.pdf Accessed: March 6, 2007.

Of the 2 agents used for myocardial perfusion imaging, technetium Tc 99m has more favorable imaging characteristics.⁹ It has a shorter half-life (6 hours) than thallium Tl 201 (73 hours), and larger doses of technetium Tc99m may be used, permitting the assessment of ventricular function.¹⁰

Echocardiography may also be done with either exercise treadmill testing or PSMI to evaluate relative myocardial perfusion. While radionuclide technique assesses relative myocardial perfusion, echocardiography also evaluates global and regional function. Indications for echocardiography are similar to myocardial perfusion imaging but also include the need for prognostic information after MI, and to assess physiologic significance of a lesion or to determine the success of an intervention.