Management of Prominent ST Changes During Treadmill Stress Testing

Diagnostic Considerations

The European Society of Cardiology recommends that exercise ECG has no diagnostic value in patients with ECG abnormalities at rest that prevent interpretation of ST-segment changes during stress, including ≥0.1 mV ST-segment depression on resting ECG 1
Baseline ST segment abnormalities fundamentally compromise the diagnostic accuracy of standard exercise ECG testing, leading to both false-positive and false-negative results 2

The American College of Physicians and European Society of Cardiology recommend stress testing with an imaging modality, such as exercise echocardiography or exercise myocardial perfusion imaging, rather than proceeding directly to invasive coronary angiography or stopping the diagnostic workup 3, 4, 5
Exercise echocardiography and exercise myocardial perfusion imaging provide superior diagnostic accuracy compared to ECG changes alone when baseline abnormalities are present 2, 5

The Duke Treadmill Score should still be calculated to guide the urgency and type of further testing, even though the ST changes themselves are not reliably interpretable 3, 4
Patients with a low-risk Duke Treadmill Score (≥5) have an excellent prognosis, but may still require imaging for definitive evaluation if asymptomatic with prominent ST changes 3, 4
Patients with an intermediate-risk Duke Treadmill Score (-10 to +4) should undergo exercise myocardial perfusion imaging or exercise echocardiography 3, 4
Patients with a high-risk Duke Treadmill Score (≤-11) should undergo exercise myocardial perfusion imaging or exercise echocardiography, with consideration for direct coronary angiography if high-risk features are present 3, 4, 5

Exercise capacity, with <5 METs or inability to achieve 85% maximum predicted heart rate, indicates higher risk 1
Symptoms during exercise, such as typical angina, especially at low workload, are prognostically significant 2, 1
Arrhythmias, such as ventricular arrhythmias during exercise, are also prognostically significant 5

Coronary angiography should be considered without intermediate stress imaging in specific high-risk scenarios, such as recurrent symptoms despite adequate medical therapy, heart failure, or serious ventricular arrhythmias 5
High-risk Duke Treadmill Score (≤-11) with limiting symptoms is also an indication for direct coronary angiography 5, 3

Baseline ST segment abnormalities, including ST elevation, interfere with accurate interpretation of exercise-induced ST segment changes, which are the primary diagnostic markers during standard exercise ECG testing 6
The American College of Cardiology/American Heart Association guidelines explicitly recommend that patients with resting ST changes that may interfere with interpretation should have an imaging modality added to their stress test 7, 8
Treadmill exercise testing is only useful in patients whose ECG is free of resting ST changes that could interfere with interpretation 9, 10

Exercise stress testing with imaging is the recommended approach for patients who can exercise but have baseline ST segment elevation 10, 6
Imaging modalities that can be added to exercise testing include:
- Echocardiography 11
- Nuclear myocardial perfusion imaging 11
Pharmacological stress testing with imaging should be used if the patient also has physical limitations that preclude adequate exercise 7, 8

ST segment changes during exercise are the primary diagnostic markers for ischemia in standard treadmill testing 12
This ambiguity significantly reduces the diagnostic accuracy of standard treadmill testing without imaging 6

Performing standard treadmill testing without imaging in patients with baseline ST elevation can lead to false negative results due to inability to detect additional ST changes 11
Performing standard treadmill testing without imaging in patients with baseline ST elevation can lead to false positive results due to misinterpretation of baseline abnormalities 11

Patients with an abnormal treadmill exercise ECG should be referred to stress imaging (exercise echocardiography or myocardial perfusion imaging) rather than proceeding directly to invasive coronary angiography, unless high‑risk clinical features mandate immediate angiography. 13

A high‑risk Duke Treadmill Score (≤ ‑11) indicates marked ischemia at low workload and warrants stress imaging, with consideration of immediate coronary angiography if the patient has limiting symptoms. 14
A low‑risk Duke Treadmill Score (≥ 5) combined with an exercise capacity > 10 metabolic equivalents and a negative ECG predicts an excellent prognosis, making further downstream testing generally unnecessary. 14

Exercise ECG alone has modest performance for detecting obstructive coronary artery disease, with a sensitivity of approximately 58 % and a specificity of 62 %. 15
Although an abnormal exercise ECG remains a specific marker for obstructive disease and predicts future revascularization and myocardial infarction, a substantial proportion of both obstructive and non‑obstructive CAD can be missed without adjunctive imaging. 13

Abnormal blood‑pressure responses during exercise—either excessive hypertension or a drop in systolic pressure—are associated with higher cardiovascular risk. 15

Do not repeat a standard exercise ECG when any of the following baseline abnormalities are present:

Even in patients classified as low‑risk by the Duke Treadmill Score, an abnormal exercise ECG may still require stress imaging because significant coronary disease can remain undetected without it. 14

In low‑risk symptomatic women, exercise ECG provides diagnostic effectiveness comparable to exercise myocardial perfusion scintigraphy, with similar two‑year major adverse cardiovascular event rates and notable cost savings; however, stress imaging should still be considered if the ECG is abnormal. 13