Exercise echocardiography testing in asymptomatic patients after revascularization identified those at high risk of all-cause and cardiac death, according to a study published June 11 in the Archives of Internal Medicine. But revascularization based on these positive findings did not alter the course of disease or patient outcomes, prompting the researchers to recommend careful consideration before screening asymptomatic patients.
The American College of Cardiology and American Heart Association guidelines recommend using exercise echocardiography among possible stress imaging tests to evaluate symptomatic patients after PCI and coronary artery bypass graft (CABG) surgery. But the use of these tests for asymptomatic patients is more controversial, wrote Serge C. Harb, MD, of the department of cardiovascular medicine at the Cleveland Clinic Heart and Vascular Institute, and colleagues. Early testing—that is, testing less than two years after PCI and five years after CABG surgery—is considered inappropriate while testing after these cutoff periods is deemed of indeterminate value.
“The inappropriate use of noninvasive testing is not only costly but also could lead to unnecessary downstream testing and interventions such as coronary angiography and revascularization,” Harb and colleagues wrote. Their goal was to examine the effectiveness of early and late testing of asymptomatic patients after revascularization and treatment responses to determine whether treatment made a difference in outcomes.
The researchers conducted an observational retrospective study using prospective data on PCI and CABG patients referred for exercise echocardiography at the Cleveland Clinic between 2000 and 2010. They identified 2,105 asymptomatic patients with a history of MI; 1,143 had undergone PCI while 962 had undergone CABG. Their primary endpoints were repeat revascularization within six months of the screening results and cardiac and all-cause mortality after a mean follow-up of 5.7 years.
Testing identified 13 percent of patients as having ischemia. Of those, only 34 percent underwent revascularization. Among those with nonischemic test results, 49 percent had a second or subsequent test and the rate of revascularization ranged from 33 percent for patients with positive results to 12 percent for patients without ischemia.
There were 97 deaths (4.6 percent) for an annualized mortality rate of 0.8 percent. Mortality was associated with ischemia, and patients with ischemia on an exercise echocardiography test post-revascularization had a higher mortality than those without ischemia, at 8 percent and 4.1 percent, respectively.
Harb and colleagues observed that patients and physicians often chose to not act when presented with ischemic results. “Among patients with evidence of ischemia, 66 percent did not undergo RVS [revascularization], and of those who underwent RVS, 75 percent did not have ischemia on their ExE [exercise echocardiography]. The decision to proceed with RVS was based more on the change in the clinical status of the patient with development of ischemic symptoms than on the sole result of the test,” they wrote.
They continued that from a prognostic standpoint, their results suggest that using a combination of clinical and exercise echocardiography test data is effective for identifying at-risk patients although revascularization is unlikely to benefit them. “To our knowledge, no previous study of exercise echocardiography in asymptomatic patients post-revascularization addressed the incremental value of imaging to clinical and stress testing findings,” they wrote.
Given the apparent lack of benefit for post-PCI and post-CABG patients, though, they recommended that physicians deliberate before screening asymptomatic patients. “From a health economic standpoint, appropriateness of such testing must be carefully reviewed,” they concluded.