Is the DTS valid for women?

The original DTS was derived predominantly from male populations. While it has been validated in women, exercise ECG testing has lower sensitivity and specificity in women due to hormonal effects on ST segments. Some experts recommend stress imaging over exercise ECG alone for women.

What if the patient did not reach 85% of max HR?

A submaximal test is less reassuring. The DTS can still be calculated, but the result should be interpreted more cautiously and alongside the reason the target was not reached.

Does the DTS account for pre-existing ECG abnormalities?

No. Baseline ST abnormalities (LVH, digoxin, LBBB) reduce the diagnostic value of exercise ST changes. The DTS should be interpreted cautiously in these patients, and stress imaging is preferred.

How does exercise capacity alone predict outcomes?

Exercise capacity (METs) is one of the strongest predictors of all-cause mortality, independent of other factors. Patients achieving <5 METs have significantly worse prognosis. Each 1-MET increase in capacity is associated with 10-15% reduction in mortality.

When should I proceed to catheterization vs. stress imaging?

A low score may not need more testing, a moderate score often leads to stress imaging, and a high score may lead to angiography depending on the rest of the case.

What is chronotropic incompetence?

Chronotropic incompetence is the inability to achieve 85% of age-predicted max HR despite adequate effort (in the absence of beta-blockers or rate-limiting medications). It is an independent predictor of cardiac events and all-cause mortality.

Duke Treadmill Score Calculator

Calculate the Duke Treadmill Score from exercise stress test results. Estimates annual cardiac mortality risk and guides need for coronary angiography.

⚠️ Medical Disclaimer: This calculator is for educational purposes. Duke Treadmill Score interpretation requires clinical context including pre-test probability, symptoms, and imaging results.

Exercise Time (Bruce Protocol)

minutes

Max ST-Segment Deviation

Angina During Exercise

Age

years

Max Heart Rate Achieved

bpm

Duke Treadmill Score2.0

High Risk (<−10)Moderate (−10 to +4)Low Risk (≥+5)

Annual Cardiac Mortality

2-3%

Moderate Risk

Intermediate risk — consider further testing or catheterization

Duke Treadmill Score

2.0

Moderate Risk: annual mortality 2-3%

Risk Category

Moderate Risk

Intermediate risk — consider further testing or catheterization

Exercise Capacity

4.0 METs

Poor

% Max HR Achieved

88%

Adequate (≥85%)

Predicted Max HR

165 bpm

220 − 55 = 165

Chronotropic Index

Normal

Inability to reach 85% max HR may indicate chronotropic incompetence

DTS = Exercise Time − (5 × ST deviation) − (4 × Angina Index)

DTS = 7 − (5 × 1) − (4 × 0)

DTS = 7 − 5 − 0 = 2.0

Risk Category	DTS Range	Annual Mortality	5-Year Survival
Low Risk	≥ +5	<1%	97%
Moderate Risk	−10 to +4	2-3%	90%
High Risk	< −10	≥5%	75%

Bruce Protocol Stage	Time (min)	Speed (mph)	Grade (%)	Approx METs
Stage 1	0-3	1.7	10	5
Stage 2	3-6	2.5	12	7
Stage 3	6-9	3.4	14	10
Stage 4	9-12	4.2	16	13
Stage 5	12-15	5.0	18	16

Planning notes, formulas, and examples

About the Duke Treadmill Score Calculator

The Duke Treadmill Score (DTS) Calculator interprets exercise stress test results and places the patient into low, moderate, or high cardiac risk groups. It combines exercise time, ST-segment deviation, and exercise-related angina into a single score.

Low scores point toward higher risk, while higher scores are more reassuring. The result is most useful when it is read alongside the exercise report and the patient's overall clinical picture.

When This Page Helps

Use the Duke Treadmill Score to turn stress-test findings into a clearer risk estimate. It helps show when the test is reassuring and when further evaluation may be worth considering.

The score is especially useful when the exercise ECG findings need to be summarized for follow-up decisions or referral.

How to Use the Inputs

Perform a standard Bruce protocol treadmill exercise test.
Record the total exercise time in minutes.
Measure the maximum ST-segment deviation (depression or elevation) in mm.
Note whether angina occurred and whether it was limiting.
Enter the patient age and maximum heart rate achieved.
Review the Duke Treadmill Score and risk category.
Use the result to guide decisions about further testing.

Formula used

Duke Treadmill Score = Exercise Time (minutes) − (5 × max ST deviation in mm) − (4 × Angina Index)

Angina Index: 0 = no angina; 1 = non-limiting angina; 2 = exercise-limiting angina

Low Risk: DTS ≥ +5 (annual mortality <1%)
Moderate Risk: DTS −10 to +4 (annual mortality 2-3%)
High Risk: DTS < −10 (annual mortality ≥5%)

Example Calculation

Result: DTS = 2 — Moderate Risk (2-3% annual mortality)

DTS = 7 min − (5 × 1 mm) − (4 × 0) = 7 − 5 − 0 = 2. A score between −10 and +4 indicates moderate risk with approximately 2-3% annual cardiac mortality. Further non-invasive imaging or clinical correlation is recommended.

Tips & Best Practices

The Bruce protocol is the standard — other protocols require different time-to-METs conversions.
ST depression in lead V5 has the highest sensitivity for coronary disease.
ST elevation during exercise (other than aVR) suggests transmural ischemia or vasospasm.
Recovery ST changes (occurring after exercise) carry the same significance as exercise changes.
Exercise capacity may be more prognostic than ST changes in many populations.
Consider beta-blocker effects — holding for 24-48 hours before testing improves sensitivity.

Validation and Performance

The DTS has been validated in over 10,000 patients across multiple institutions. In the original Duke cohort, the score correctly stratified patients into risk categories with 5-year survival of 97% (low risk), 90% (moderate), and 75% (high risk). The score performs best in intermediate pre-test probability populations.

Beyond the DTS

Additional exercise test features provide prognostic information: exercise-induced ventricular arrhythmias, abnormal heart rate recovery (failure to decrease >12 bpm in the first minute post-exercise), and abnormal blood pressure response. Integrating these with the DTS provides more refined risk assessment.

Modern Alternatives

Stress echocardiography and nuclear perfusion imaging provide functional and anatomic information beyond exercise ECG. CT coronary angiography offers direct anatomic visualization. However, the standard exercise test with DTS calculation remains a cost-effective first-line evaluation for patients capable of adequate exercise.

Sources & Methodology

Last updated: March 26, 2026

Methodology

This calculator applies the standard Duke Treadmill Score equation by combining exercise duration, maximal ST-segment deviation, and angina during exercise into the familiar low-, intermediate-, and high-risk bands. The output is meant to summarize the prognostic signal from a standard exercise ECG stress test rather than to replace the full stress-test report.

The score is most defensible in patients who complete an interpretable exercise ECG test. Baseline ECG abnormalities, submaximal effort, non-treadmill protocols, and the broader clinical context can all change how the result should be used, so the page should be treated as a risk-summary aid rather than a catheterization rule by itself.

Sources

Exercise treadmill score for predicting prognosis in coronary artery disease (PubMed / Annals of Internal Medicine)
Value of exercise treadmill testing in women (PubMed / Journal of the American College of Cardiology) — Validation paper relevant to sex-specific interpretation of the Duke Treadmill Score.

Frequently Asked Questions

The original DTS was derived predominantly from male populations. While it has been validated in women, exercise ECG testing has lower sensitivity and specificity in women due to hormonal effects on ST segments. Some experts recommend stress imaging over exercise ECG alone for women.