Should a stress test be ordered for a patient with suspected angina and intermediate to high risk of cardiovascular events?

Should You Order a Stress Test for Suspected Angina?

Yes, exercise stress testing should be ordered for patients with suspected angina who have intermediate to high probability of coronary artery disease, as this is essential for risk stratification to determine subsequent coronary events and mortality risk. 1

Patient Selection for Stress Testing

Exercise ECG using the Bruce protocol with Duke treadmill score should be the initial test for patients with suspected chronic stable angina who meet the following criteria: 1, 2

• Able to exercise adequately
• Normal or near-normal resting ECG
• Not taking digoxin
• Intermediate to high probability of CAD (15-85% pre-test probability) 1

The European Society of Cardiology specifically recommends exercise ECG for patients with pre-test probability of 15-65%, while stress imaging is preferred for those with 66-85% probability or reduced left ventricular ejection fraction. 1

When NOT to Order Exercise ECG

Exercise ECG testing is contraindicated or non-diagnostic in the following situations, requiring stress imaging instead: 1

• Wolff-Parkinson-White syndrome
• Electronically paced ventricular rhythm
• Complete left bundle-branch block
• More than 1 mm ST depression at rest
• Patients taking digoxin
• Unable to exercise adequately

For these patients, pharmacologic stress imaging (echocardiography, SPECT, PET, or CMR) should be used as the initial test. 1

Risk Stratification Using Duke Treadmill Score

The Duke treadmill score provides critical prognostic information that directly impacts mortality: 1, 2

• Low risk (score ≥5): 4-year survival 99% (0.25% annual mortality) - no angiography needed
• High risk (score ≤-10): 4-year survival 79% (5% annual mortality) - proceed to angiography

The formula is: Exercise time (minutes) − (5 × ST deviation in mm) − (4 if angina occurs) − (8 if angina causes test termination). 1, 2

This score performs equally well in men and women, though it may be less reliable in patients older than 75 years. 1

Alternative Testing Strategies

For patients with low-intermediate pre-test probability (15-50%), coronary CTA may be considered as an alternative to ischemia testing, provided adequate technology and local expertise are available. 1

Stress imaging (echocardiography or nuclear perfusion) is recommended for: 1, 3

• Abnormal resting ECG
• Prior coronary revascularization
• Inability to exercise adequately
• Women (though standard exercise ECG remains acceptable as initial test) 1

Clinical Pitfalls to Avoid

Do not order stress testing in truly low-risk patients (pre-test probability <15%), as this leads to false-positive results and unnecessary downstream testing. 1

Do not repeat stress testing within 3 years in patients without change in clinical status. 4

Do not delay angiography by ordering stress testing in patients with high-risk clinical features (severe symptoms, prior positive stress test, known multivessel disease) - proceed directly to coronary angiography. 4

Exercise stress testing is more useful for ruling out CAD than confirming it - a negative test in appropriate patients has excellent negative predictive value (annual cardiac event rate 0.9%), while positive tests require correlation with clinical context. 1, 5, 6