What is the best management for patients with evidence of asymptomatic ischemia on exercise stress testing?

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What is the best management for patients with evidence of asymptomatic ischemia on exercise stress testing?

J Fam Pract. 2007 January;56(1):53-55

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References

1. Gibbons RJ, Balady GJ, Bricker JT, et al. AHA/ACC 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. American College of Cardiology Web site. Available at: www.acc.org/qualityandscience/clinical/guidelines/exercise/dirindex.htm. Accessed on December 13, 2006.

2. Mark DB, Shaw L, Harrell FE, Jr, et al. Prognostic value of a treadmill exercise score in outpatients with suspected coronary artery disease. N Engl J Med 1991;325:849-853.

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

4. Nishime EO, Cole CR, Blackstone EH, et al. Heart rate recovery and treadmill exercise score as predictors of mortality in patients referred for exercise ECG. JAMA 2000;284:1392-1398.

5. Gibbons RJ, Hodge DO, Berman DS, et al. Long-term outcome of patients with intermediate-risk exercise electrocardiograms who do not have myocardial perfusion defects on radionuclide imaging. Circulation 1999;100:2140-2145.

6. Lauer MS. Exercise electrocardiogram testing and prognosis. Novel markers and predictive instruments. Cardiol Clin 2001;19:401-414.

7. Gibbons LW, Mitchell TL, Wei M, et al. Maximal exercise testing as a predictor of risk for mortality from coronary heart disease in asymptomatic men. Am J Cardiol 2000;86:53-58.

8. Laukkanen JA, Kurl S, Lakka TA, et al. Exercise-induced silent myocardial ischemia can coronary morbidity and mortality in middle-aged men. J Am Coll Cardiol 2001;38:72-79.

9. Multiple Risk Factor Intervention Trial Research Group. Exercise electrocardiogram and coronary heart disease mortality in the Multiple Risk Factor Intervention Trial. Am J Cardiol 1985;55:16-24.

10. Paffenbarger RS, Hyde RT, Wing AL, et al. The association of changes in physical-activity level and other lifestyle characteristics with mortality among men. N Engl J Med 1993;328:538-545.

11. Blair SN, Kohl HW, Barlow CE, et al. Changes in physical fitness and all-cause mortality: A prospective study of healthy and unhealthy men. JAMA 1995;272:1093-1098.

12. Mosca L, Appel LJ, Benjamin EJ, et al. Evidence-based guidelines for cardiovascular disease prevention in women. Circulation 2004;109:672-693.

While risk factor reduction seems logical for all patients who have asymptomatic ischemia, actual evidence of benefit is limited. In the MRFIT study,⁹ high-risk men with asymptomatic ischemia were randomized to either usual care or a special intervention to reduce smoking, blood cholesterol, and diastolic blood pressure. The intervention group had lower cardiac mortality than men who received usual care (22 vs 53 per 1000, P<.002).⁹ As observed in 2 large prospective cohort studies, one of which documented abnormal EST in 17%, males who improved their fitness had 23% (95% CI, 4–42) and 44% (95% CI, 5–59) lower mortality over 18 years of mean follow-up, respectively.^10,11 Smoking cessation is also important, associated with 41% lower mortality (95% CI, 20–57).¹¹

Most of the evidence underlying the above recommendations derives from studies of men and hence may not apply directly to women. The American Heart Association’s guidelines¹² for cardiovascular disease prevention in women do not consider EST results in risk assessment. They rely instead on the Framingham Risk Score to stratify women’s 10-year risk of coronary events as low (<10%), intermediate (10%–20%), and high (>20%), and prioritize recommendations for risk factor reduction according to these levels.¹²

TABLE
Duke Treadmill Scores: 5-year all-cause mortality

ABNORMALITIES OBSERVED ON TREADMILL TESTING
NONE	DTS only	HRR only	CI only	HRR & CI	DTS & CI	HRR & DTS	CI, HRR, & DTS
0.9	3.2	4.0	4.0	8.2	9.2	9.2	18.0
Example: Patients having abnormal Duke Treadmill score and Chronotropic Index but normal Heart rate recovery sustained 5-year, all-cause mortality of 9.2%. Those with abnormal DTS and HRR but normal CI coincidentally had the same 9.2% mortality.⁶
Duke Treadmill Test (DTS): Minutes in standard Bruce protocol –5 × (maximal ST deviation in mm) –4 × (0=no chest pain, 1=angina during EST, 2=EST stopped due to angina).
Heart Rate Recovery (HRR): abnormal if heart rate drops less than 12 bpm measured at least 2 minutes after stopping EST.
Chronotropic Index (CI): represents the ratio of heart rate reserve compared to metabolic reserve.
Normal is near 1.

Recommendations from others

American College of Cardiology/American Heart Association (ACC/AHA) guidelines¹ favor medical treatment for low-risk patients with asymptomatic ischemia (annual cardiac mortality ≤1%—ie, DTS ≥5, or normal HRR or normal CI). The ACC/AHA recommend perfusion imaging (or exercise echocardiography) for patients with asymptomatic ischemia who have intermediate or high-risk DTS.¹ Such imaging can refine prognosis, guide therapy with aspirin, beta blockers, lipid-lowering agents, and angiotensin-converting enzyme inhibitors, and possibly identify patients who might benefit from coronary angiography and revascularization (AHA/ACC Recommendation Class IIa–IIb, Level of Evidence B–C).

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What is the best management for patients with evidence of asymptomatic ischemia on exercise stress testing?

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