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Stress Echo in Asymptomatic Revascularized Patients Not Useful

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Not Worth the Effort

"The results presented by Harb et al. make a compelling argument that routine periodic stress testing in asymptomatic patients following coronary revascularization is of little clinical benefit" and "probably not worth the effort," said Dr. Mark. J. Eisenberg.

However, the methodology did not address two issues that might bear on the appropriateness of stress echocardiography. First, if the index revascularization was incomplete, treating physicians might be justified in ordering a stress test. This study did not report the rate of incomplete revascularization in the study subjects.

Second, stress echocardiography is reasonable to perform before patients enter cardiac rehabilitation, and this study did not report how many of the tests in this cohort were done for that reason.

Mark J. Eisenberg, M.D., is in the divisions of cardiology and clinical epidemiology at Jewish General Hospital and in the department of epidemiology, biostatistics, and occupational health at McGill University, both in Montreal. He reported no financial conflicts of interest. These remarks were taken from his invited commentary accompanying Dr. Harb’s report (Arch. Intern. Med. 2012 May 14 [doi:10.1001/archinternmed.2012.1910]).


 

FROM ARCHIVES OF INTERNAL MEDICINE

Routine exercise stress echocardiography may not be warranted in asymptomatic patients after coronary revascularization because even though it may identify those at high risk, this does not improve patient outcomes, according to a report published online May 14 in Archives of Internal Medicine.

"Given the very large population of post-PCI and post-CABG patients, careful consideration is warranted before the screening of asymptomatic patients is considered appropriate at any stage after revascularization," said Dr. Serge C. Harb and his associates at the Cleveland Clinic Heart and Vascular Institute.

Exercise stress echocardiography is useful in symptomatic patients after revascularization because it can identify the cause of the symptoms and allow further treatment to relieve them, which is usually highly effective. However, its role in asymptomatic patients is controversial because there is no evidence that identifying problems that cause no symptoms leads to better treatment, nor that treatment improves the course of the disease or patient outcomes.

Dr. Harb and his colleagues assessed the usefulness of exercise stress echocardiography in asymptomatic patients in an observational cohort study of 2,105 consecutive patients referred for such testing to their institute in 2000-2010. Patients were referred "solely at the discretion of individual physicians treating the patient, usually on the basis of concerns regarding risk factor status or incomplete revascularization," the researchers said.

Such testing is considered inappropriate when it is done too soon after the revascularization – less than 2 years after percutaneous coronary intervention (PCI) and less than 5 years after coronary artery bypass graft surgery (CABG). In this study, 1,143 study subjects had undergone PCI (709 referred for "early" and 434 for appropriate stress echocardiography) and 962 had undergone CABG (527 referred for "early" and 435 for appropriate stress echocardiography).

There were five major findings.

First, only 13% of the entire study population showed evidence of ischemia on stress echocardiography – a low yield of positive findings for this expensive procedure, the authors noted.

Second, abnormal results on stress echocardiography were associated with significantly higher risks of overall and cardiac mortality during a mean follow-up of 6 years. Mortality was 8.0% in patients who showed ischemia on stress testing, compared with only 4.1% in those who had no ischemia. However, identifying these high-risk patients made no difference in the eventual outcomes of the study cohort.

Interestingly, there was no distinction in the prognostic usefulness of stress echocardiography between patients who underwent "early" and those who underwent appropriate testing. This suggests that these cutoff times, which were based on expert opinion, are somewhat arbitrary and not useful for prognosis, the investigators said (Arch. Intern. Med. 2012 May 14 [doi:10.1001/archinternmed.2012.1355]).

Third, the main component of stress echocardiography that was found to be predictive was exercise capacity. This indicates that standard exercise testing rather than exercise echocardiography might be sufficient for risk evaluation.

Fourth, when exercise echocardiography did identify evidence of ischemia in a minority of patients, the findings were not acted upon in most cases. Only 33% of the 262 patients with positive results underwent further revascularization. Thus, the test results led to repeat revascularization in only 87 patients out of 2,105 who were tested. That’s because the decision to do repeat revascularization was based more on the development of symptoms after testing rather than on the results of the test.

Fifth, further revascularization procedures did not produce more favorable mortality outcomes.

"Our results suggest that from a prognostic standpoint, a combination of clinical and exercise data is effective in identifying patients at highest risk, even though they are unlikely to benefit from repeat revascularization," Dr. Harb and his associates said.

Dr. Rita F. Redberg, editor of Archives of Internal Medicine, noted that the recommendation "Do not perform serial stress cardiac imaging or advanced noninvasive imaging as part of routine follow-up in asymptomatic patients" is one of the Top 5 recommendationsfor the American College of Cardiology in the American Board of Internal Medicine Foundation’s "Choosing Wisely" campaign. Dr. Redberg, who is professor of medicine and director of Women’s Cardiovascular Services at the University of California, San Francisco, also gave the recommendation a "Less Is More" designation, which highlights areas of health care with no known benefit and definite risks.

Dr. Redberg has no relevant financial disclosures.

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