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Author Affiliations: Divisions of Cardiology and Clinical Epidemiology, Jewish General Hospital, Faculty of Medicine, and Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada.
The confluence of increasing budgetary restrictions and the proliferation of medical imaging make the appropriateness of routine periodic stress testing in asymptomatic patients following coronary revascularization a hotly debated topic.1,2 Routine periodic stress testing is still used by many physicians. Putative reasons include surveillance for restenosis after percutaneous coronary intervention (PCI), identification of graft patency after coronary artery bypass graft (CABG) surgery, and determination of completeness of revascularization. However, the usefulness of routine periodic stress testing in asymptomatic patients following coronary revascularization remains unknown.
Stress testing can be performed with exercise alone or in combination with echocardiographic or nuclear imaging. Many studies have demonstrated the prognostic ability of these tests, with ischemia demonstrated on routine testing indicating worse prognosis.3 The addition of ventricular imaging to exercise testing alone increases sensitivity, specificity, and prognostic ability. Unfortunately, there are little data to support the idea that revascularizing asymptomatic patients on the basis of these studies actually improves prognosis.
Guidelines and appropriateness statements abound that touch on the issue of routine periodic stress testing after coronary revascularization. We have statements about PCI, CABG, stress testing, echocardiography, and nuclear imaging. There is some inconsistency among these statements. For example, the 2011 Guideline for Percutaneous Coronary Intervention of the American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions (SCAI)4(pE617) states: “Routine periodic stress testing of asymptomatic patients after PCI without specific clinical indications should not be performed” (class III recommendation, level of evidence C). In contrast, the 2011 Appropriate Use Criteria for Echocardiography by the ACCF Appropriate Use Criteria Task Force, American Society of Echocardiography (ASE), AHA, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, SCAI, Society of Critical Care Medicine, Society of Cardiovascular Computed Tomography, and Society for Cardiovascular Magnetic Resonance suggest that stress echocardiography less than 2 years following PCI is inappropriate, but the appropriateness after 2 or more years is uncertain; similarly, stress echocardiography less than 5 years following CABG is considered inappropriate, but the appropriateness after 5 or more years is uncertain.5 Moreover, an earlier guideline statement on exercise testing suggests that routine stress testing post-PCI may be appropriate in certain high-risk subgroups, including patients with aborted sudden death, silent ischemia, diabetes mellitus, PCI of the left main, and low ejection fraction.6
In this issue of the Archives, Harb et al7 present the results of their study addressing the issue of routine stress echocardiography in asymptomatic patients following coronary revascularization. The authors performed a retrospective study in 2105 asymptomatic patients who underwent exercise echocardiography at the Cleveland Clinic: 1143 patients with prior PCI and 962 patients with prior CABG. They found that only 13% of patients demonstrated ischemia on routinely performed stress echocardiographic examinations and, of those, only 34% underwent subsequent revascularization. Although abnormal results were associated with subsequent mortality, the authors were unable to demonstrate that even high-risk patients benefited from repeated revascularization. They conclude that asymptomatic patients who undergo exercise echocardiography after coronary revascularization may be identified as being at high risk but that these patients do not seem to have improved outcomes with repeated revascularization. The authors further suggest that, from a health economic standpoint, the appropriateness of such testing must be carefully reviewed.
The article by Harb et al7 raises several questions. First, it is unclear how many of their patients were completely revascularized during their index revascularization. If patients were incompletely revascularized, then their treating physicians might have had a rationale for ordering a stress test. Second, current guidelines suggest that routine stress testing after coronary revascularization is reasonable to perform as an exercise prescription prior to entering a cardiac rehabilitation program.4 It is unclear how many of the tests that were done in this cohort were performed for that reason. Third, the adequacy of these stress tests could have been described in more detail. Did all patients stop their β-blockers prior to the test? What percentage of patients attained 85% of their maximum predicted heart rate? If it was less than 100%, then many of these test results may have been false-negatives. Finally, although the authors use the 2- and 5-year cutoffs from the ACCF/ASE 2011 Appropriate Use Criteria for Echocardiography,5 they point out that these cutoffs seem somewhat arbitrary. Despite these issues, however, the results presented by Harb et al7 make a compelling argument that routine periodic stress testing in asymptomatic patients following coronary revascularization is of little clinical benefit.
Very few prospective studies have examined this issue. Our group performed the ADORE I8 and ADORE II9 trials in which post-PCI patients were randomized to routine exercise testing with myocardial perfusion imaging vs conservative management. We were unable to demonstrate that routine stress testing leads to better clinical outcomes. As far as I am aware, there have been no randomized trials of exercise echocardiography in asymptomatic patients postrevascularization. However, there is little expectation that routine stress testing, when examined in a randomized manner, would result in findings different than those of Harb et al.7 Routine stress testing will identify a subgroup of patients with silent ischemia. However, there is little evidence in the literature to suggest that repeated revascularization of these patients will improve clinical outcomes.
A strategy of routine periodic stress testing in asymptomatic patients following coronary revascularization is associated with high rates of resource utilization and high costs. Most positive test results using such a strategy will be false-positives and will lead to further testing and additional angiographic procedures.4 Despite the fact that current evidence discourages the use of routine testing, this strategy is still commonly observed in practice.10 Thus, the time has arrived for a large, well-controlled trial randomizing asymptomatic patients postrevascularization to routine periodic stress testing vs conservative management. Until well-supported data become available supporting such a strategy, routine testing in asymptomatic patients is probably not worth the effort.
Correspondence: Dr Eisenberg, Divisions of Cardiology and Clinical Epidemiology, Jewish General Hospital, McGill University, 3755 Côte Ste-Catherine Rd, Ste H421.1, Montreal, QC H3T 1E2, Canada (email@example.com).
Published Online: May 14, 2012. doi:10.1001/archinternmed.2012.1910
Financial Disclosure: Dr Eisenberg is a National Investigator of the Quebec Fund for Health Research.
Eisenberg MJ. Routine Periodic Stress Testing in Asymptomatic Patients Following Coronary Revascularization: Is It Worth the Effort? Comment on “Exercise Testing in Asymptomatic Patients After Revascularization”. Arch Intern Med. 2012;172(11):861–863. doi:10.1001/archinternmed.2012.1910
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