Recurrent ischemia and cardiac events are common after PCI and CABG, signifying that coronary artery disease may still be progressing. Guidelines from the American College of Cardiology and the American Heart Association suggest evaluating symptomatic patients after these revascularization procedures with stress imaging tests, including exercise echocardiography (ExE). Evaluating asymptomatic patients, however, is more controversial. Testing is considered inappropriate less than 2 years after PCI and less than 5 years after CABG and of indeterminate appropriateness thereafter, but the justification for these cutoffs has not been well defined in clinical research.
“Careful consideration is needed before screening asymptomatic patients at any stage after revascularization.”
While the presence of ischemia on an ExE can help predict adverse outcomes after PCI and CABG, there is no evidence that repeated revascularization based on positive testing can change the course of the disease or patient outcomes. When noninvasive testing is used inappropriately, it can be costly to patients and the healthcare system. It can also lead to unnecessary downstream testing and interventions, such as coronary angiography and repeat revascularization.
Testing Asymptomatic Patients After PCI & CABG
In the May 14, 2012 Archives of Internal Medicine, my colleagues and I examined the effectiveness of testing asymptomatic patients early and late after revascularization using data from asymptomatic patients with a history of PCI or CABG who were referred for ExE. We looked at the frequency of a positive response, the association of test results with subsequent revascularization and mortality, and the presence of any interaction of revascularization with these event rates. ExE was performed in 2,105 asymptomatic patients, 54% of whom received PCI while 46% had undergone CABG an average of 4.1 years before the ExE.
Ischemia was detected in 262 patients in the study, but only about one-third (88) underwent repeated revascularization. Higher mortality rates were observed in patients with ischemia; however, repeat revascularization based on the ExE results did not decrease mortality or alter outcomes even in high-risk patients. We also found that the main predictors of outcome appeared to be clinical and stress testing findings, rather than echocardiographic features. This suggests that risk evaluation could be obtained from a standard exercise test, rather than ExE.
Analyzing the Implications
Results of our study suggest that asymptomatic patients who undergo treadmill ExE after coronary revascularization may be identified as being high risk but don’t appear to have more favorable outcomes with repeated revascularization. Since many patients in the United States undergo PCI and CABG each year, careful consideration is needed before screening asymptomatic patients at any stage after revascularization. Routine periodic stress testing in asymptomatic patients after their revascularization procedure will likely increase resource utilization and costs. It could also lead to additional testing and procedures without clear benefit to the patient. Routine testing in asymptomatic patients after PCI or CABG is most likely not worth the effort.