Is Routine Stress Testing After Coronary Revascularization Necessary?
By Michael H. Crawford, MD
Professor of Medicine, Lucy Stern Chair in Cardiology, University of California, San Francisco
SYNOPSIS: A multicentered study of routine stress testing at one year post-percutaneous coronary revascularization compared to usual care in patients with at least one high-risk coronary anatomic or clinical feature failed to show improved clinical outcomes at two years follow-up.
SOURCE: Park DW, Kang DY, Ahn JM, et al. Routine functional testing or standard care in high-risk patients after PCI. N Engl J Med 2022;387:905-915.
Although widely employed, there are little data supporting routine cardiac stress testing after percutaneous coronary artery interventions (PCI). Researchers from South Korea conducted a multicenter, pragmatic, randomized, superiority trial that included high-risk post-PCI patients. Researchers tested the effect on outcomes of a strategy of routine stress testing vs. usual care.
Patients who underwent successful contemporary PCI (drug-eluting stents, bioresorbable scaffolds) and presented with at least one high-risk coronary artery anatomical feature (e.g., left main or bypass graft lesion) or clinical characteristics associated with a higher risk of experiencing subsequent ischemic or thrombotic events (e.g., patients with diabetes, renal failure, or acute coronary syndrome) were eligible for inclusion. The routine stress testing group underwent the test at 12 months after the index PCI. The usual care group could undergo stress testing when clinically indicated. Almost all the stress tests employed non-invasive imaging rather than electrocardiography alone. The treating physician at each participating center made all subsequent clinical decisions. The primary outcome was a composite of death, myocardial infarction, or hospitalization for unstable angina after two years of follow-up.
From 2017 to 2019, Park et al randomized 1,706 patients at 11 sites in South Korea (mean age = 65 years; 80% men). Among patients in the stress testing group who were available for a test (i.e., alive, no clinically indicated testing or revascularization) at 12 months, 93% were tested. In the usual care group, 9% underwent clinically indicated stress testing. Follow-up was complete at two years for 98% of patients. There were no outcome differences between the two groups at one year.
At two years, 5.5% of the stress testing group and 6% of the usual care group experienced a primary outcome event (P = 0.62). Clinicians performed invasive coronary angiography in 12.3% and 9.3% (P = not significant) and repeat revascularization in 8.1% and 5.8%, respectively (P = not significant). The authors concluded that a strategy of routine stress testing in post-PCI patients with high-risk coronary anatomic or clinical features compared to usual care did not improve clinical outcomes at the two-year follow-up mark.
This study follows the trend of older research (i.e., trials that included bare metal stents) and more recent studies, which failed to support the routine application of any testing strategy in patients with coronary artery disease. Park et al did not refute the reasoned application of stress testing where clinically indicated, which usually means the pursuit of the cause of symptoms. Also, routine stress testing is unlikely to detect or predict certain events after PCI, such as stent thrombosis caused by non-compliance with dual antiplatelet therapy. Thus, there really is not much evidence to support recommending routine stress testing post-PCI.
Park et al demonstrated routine testing leads to more procedures with little benefit. In this study, the number of invasive angiography and stenting procedures in the routine group was double that of the usual care group — for no apparent benefit. Although it seems routine stress testing after PCI continues, this study points out the futility of this practice (unless clinically indicated). It will be interesting to see if the next iteration of relevant guidelines on this matter change.
Meanwhile, consider the weaknesses of this study. For instance, the number of outcome events was less than predicted, so the study may have been underpowered to detect a significant difference. The reason for this may be related to the excellent medical care provided (e.g., 99% of patients were taking statins). Or, it could be attributed to the cutting-edge PCI procedures; 74% underwent intravascular ultrasound. Also, the study was not blinded, so ascertainment bias could have been present. There were few women enrolled, so the results could be different for them. In addition, the authors used three different types of stress testing with imaging, including standard ECG stress testing alone. Finally, several patients died before one year, so stress testing would not be expected to benefit them. Despite these weaknesses, the results of this study do not support routine testing without a clinical indication.
A multicentered study of routine stress testing at one year post-percutaneous coronary revascularization compared to usual care in patients with at least one high-risk coronary anatomic or clinical feature failed to show improved clinical outcomes at two years follow-up.
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