π Duke Treadmill Score Calculator
Turns a stress test into a risk number cardiologists trust.
For informational purposes only, not medical advice. Consult a healthcare professional.
The Duke Treadmill Score distills an exercise stress test into one number: exercise minutes minus 5 times ST depression in mm minus 4 times the angina index. A score of +5 or higher means low risk (about 0.25% yearly mortality); +4 to -10 is moderate (about 1.25%); -11 or lower is high (about 5%). Enter your three numbers above.
How to Use This Calculator
You need the three components from a completed Bruce-protocol treadmill test. They are on every standard stress test report, usually near the exercise ECG summary.
Enter total exercise time in minutes. On the Bruce protocol, each 3-minute stage gets harder; 9 minutes means finishing stage 3, which is a solid effort.
Enter the maximum ST-segment depression in millimeters, the ECG sign of heart muscle not getting enough blood during exercise. 1 mm is the usual threshold of interest.
Select the angina index: 0 for none, 1 if chest pain occurred but did not stop the test, 2 if it forced the test to stop. Read your band and the estimated annual mortality beside it.
The Duke Formula
Mark and colleagues at Duke published this in 1987 and validated it in thousands of patients. The weights are doing the clinical reasoning for you: ST depression gets a weight of 5 because a millimeter of it predicts risk more than a minute of exercise predicts safety, and limiting angina gets a 4 because pain that stops the test is ominous. Exercise time earns points because the longer you go, the more cardiac reserve you demonstrate. The score predicts all-cause mortality, going beyond cardiac events alone, and it has held up across decades of follow-up studies.
Worked Example
A patient exercises 9 minutes, develops 1 mm of ST depression, and reports chest tightness that does not stop the test (angina index 1). Duke score = 9 - 5(1) - 4(1) = 0. That lands in the moderate band (+4 to -10), with an estimated annual mortality near 1.25%. Contrast that with 12 minutes, no ST depression, no angina: 12 - 0 - 0 = +12, firmly low risk. And a bad one: 4 minutes, 2.5 mm ST depression, limiting angina: 4 - 12.5 - 8 = -16.5, high risk. Same formula, three very different prognoses, which is why the score beat any single component in the original research.
Reading the Three Bands
| Score | Band | Annual mortality | Typical next step |
|---|---|---|---|
| +5 or higher | Low | ~0.25% | Medical management, risk-factor control |
| +4 to -10 | Moderate | ~1.25% | Often further testing (imaging or angiography) |
| -11 or lower | High | ~5% | Prompt cardiology referral, usually angiography |
The mortality figures are population averages from the Duke cohorts, and your cardiologist folds in age, symptoms, and imaging before acting. The score's real power is sorting the large middle: most stress tests are not clearly normal or clearly terrible, and the Duke score gives that gray zone a number with a validated meaning. It applies to standard exercise ECG testing; pharmacologic stress tests and stress echocardiograms use different risk markers. For broader heart risk outside the stress lab, our Framingham 10-year risk calculator and blood pressure checker cover the everyday numbers that feed into events years before a treadmill is ordered.
When the Score Misleads
The Duke score assumes a maximal effort on the Bruce protocol. A test stopped early for knee pain, poor conditioning, or an abnormal blood pressure response can produce a misleadingly low score that reflects legs, not heart. Baseline ECG abnormalities like left bundle branch block or paced rhythms make ST depression unreadable, and the score should not be applied there. Women and younger patients were underrepresented in the original cohorts, so cardiologists interpret their scores with extra context. None of this makes the score useless; it makes it a tool for clinicians, which is why this page is informational and your test report's own interpretation, signed by the reading physician, is the one that counts.
Duke Score vs the Other Stress Test Numbers
The Duke score is not the only number on a stress report. Chronotropic index measures whether the heart rate rose appropriately with exercise; failing to reach 80% of the age-predicted reserve (chronotropic incompetence) predicts risk independently. Heart rate recovery, the drop in the first minute after stopping, matters too: a fall of 12 bpm or less is abnormal and linked to higher mortality. Exercise capacity in METs is arguably the single strongest predictor on the whole report. The Duke score's advantage is that it packages the three most prognostically loaded exercise variables into one validated number, and studies found it outperformed each component alone. In practice, cardiologists read all of them together: a great Duke score with poor heart rate recovery still gets attention. None of these replace imaging when the question is anatomy rather than prognosis.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
What is a good Duke Treadmill Score?
+5 or higher is low risk, the good band. The score ranges roughly from -25 to +15. Higher is better: it means long exercise time with little ECG change and no limiting chest pain.
What does a negative Duke score mean?
That the penalties outweighed the exercise time. Scores from +4 down to -10 are moderate risk; -11 or below is high risk with about 5% annual mortality in the original data. A negative score usually triggers further cardiac testing.
How is the angina index scored?
0 if no angina occurred during exercise, 1 if angina occurred but did not limit exercise or stop the test, 2 if angina was exercise-limiting and forced termination. It is judged during the test, not from your history.
Does the Duke score use the Bruce protocol only?
It was derived and validated on Bruce-protocol treadmill tests. Other protocols with different stage durations change what a minute of exercise means, so the score is most trustworthy on Bruce. Many labs report it automatically.
What is the mortality for each Duke band?
From the Duke cohorts: low risk (+5 or more) about 0.25% per year, moderate risk (+4 to -10) about 1.25% per year, high risk (-11 or less) about 5% per year. These are all-cause mortality averages, not individual predictions.
Can I calculate this from my stress test report?
Yes if the report lists exercise time in minutes, maximum ST depression in mm, and whether angina occurred and limited exercise. Most complete reports include all three. Use the physician's read of the ST changes, not your own.
Does a low-risk Duke score mean my heart is fine?
It means excellent prognosis on average, but it does not rule out all coronary disease. The score predicts mortality; some people with low scores still have plaque that needs risk-factor treatment. Keep managing blood pressure, cholesterol, and smoking regardless.
Why does ST depression get multiplied by 5?
Because in the Duke data, each millimeter of ST depression carried about five times the prognostic weight of each minute of exercise time. The weights come from the statistical model, not from intuition, which is why the score outperformed clinical judgment alone.
Is the Duke score still used today?
Yes. It remains one of the most validated exercise-test risk scores and appears in cardiology guidelines as a way to risk-stratify patients after exercise ECG testing. Newer imaging tests add information, but the score's simplicity keeps it in daily use.
What should I do with a moderate-risk score?
Talk to the ordering physician. Moderate scores commonly lead to additional testing such as stress imaging or coronary CT angiography to clarify the anatomy. Do not try to reclassify yourself with internet calculators; the next test is chosen based on your whole picture.