Stress ECG, stress echo, and myocardial perfusion imaging are all used to evaluate patients for CAD, but some experts argue that this step is no longer needed, questioning whether it adds any more value than a careful assessment of baseline risk factors in patients sans cardiac symptoms. 

Why stress testing?

Stress testing is good for detecting only significant coronary stenosis and not for non-obstructing plaques. The latter commonly cause MI, and many patients with no history of obstructive CAD experience acute MI. Thus, a negative stress test may be falsely reassuring. False-positives, however, are common in patients with a low pretest probability of CAD and have their own implications.

“Many persons with a false-positive result on stress testing undergo subsequent testing and interventions such as cardiac catheterization and revascularization,” write the authors in American Family Physician. “Up to 3% of persons who get stress tests undergo cardiac catheterization, and 1.7% of catheterizations lead to severe adverse reactions, mostly in persons without CAD.”

Screening for CAD with stress tests has not been shown to affect clinical outcomes or further inform the use of risk-reducing therapies beyond a good clinical assessment.

Across the board, institutions such as the American College of Cardiology (ACC), USPSTF, American College of Physicians, and American Academy of Family Physicians discourage cardiac screening by means of a stress test in patients who are at low risk of CAD and are asymptomatic. 

Current guidelines

The 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guidelines for the Evaluation and Diagnosis of Chest Pain discusses evidence-based criteria for initial evaluation to differentiate high- from low-risk patients and aims to reduce the rate of false-positives and false-negatives. It also explains when to obtain a resting EKG before stress testing and when to request biomarkers such as troponins.

Other considerations include when to consider a standard stress test, a stress echocardiogram, a nuclear perfusion stress test (Spect v PET), and stress magnetic resonance imaging—all of which have different false-positive and false-negative rates, as well as predictive values. 

Risk of false-positives

False-positive stress tests are common and may be due to endothelial dysfunction, microvascular abnormalities, vasomotor changes, or small-vessel coronary artery disease, as well as a form of apical ballooning syndrome.

Cho I-J. False-positive stress echocardiography: not as simple as it looks. J Cardiovasc Imaging. 2020;28(2):134–136.

A subset of patients may also experience a hypertensive response to exercise. Therefore, improved blood pressure control may be beneficial to prevent some false-positive tests.

“Stress tests aren’t great,” writes cardiologist Gregory Katz, MD. “There are a lot of false positive and false negatives, and that leads to downstream consequences.”

Katz G. Making stress tests obsolete. Gregory Katz’s Substack. April 13, 2023.

When a stress test is abnormal, the next step may be cardiac catheterization, which is an invasive procedure that carries the risk of heart attack or stroke, and requires anesthesia. It is expensive and resource-intensive, and may be unnecessary. 

Investigators publishing in NEJM randomly assigned 5,179 patients with moderate or severe ischemia to either (1) an initial invasive strategy (ie, angiography and revascularization when feasible) and medical therapy or (2) medical therapy alone and angiography if medical therapy failed. The primary outcome included a composite of death from cardiovascular causes, MI, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest. A secondary outcome was death from cardiovascular causes or MI.

Maron DJ, Hochman JS, Reynolds HR, et al.; ISCHEMIA Research Group. Initial invasive or conservative strategy for stable coronary disease. N Engl J Med. 2020;382(15):1395–1407.

“Over a median of 3.2 years of follow-up, among patients with stable coronary disease who had moderate or severe ischemia on stress testing, an initial invasive strategy, as compared with an initial conservative strategy, did not reduce the rates of the primary or key secondary composite outcomes,” the investigators concluded.

In other words, invasive strategies based on stress testing did not improve clinical outcomes.