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Printed on 6/29/2026
For informational purposes only. This is not medical advice.
The Duke Treadmill Score (DTS) is a validated prognostic index derived from exercise treadmill testing. It integrates three components: exercise time (minutes on the Bruce protocol), maximal ST-segment deviation (depression or elevation in mm), and an angina index (0 = none, 1 = non-limiting, 2 = exercise-limiting). The score stratifies patients into low risk (≥5, annual mortality <1%), moderate risk (−10 to +4, annual mortality 2–3%), and high risk (<−10, annual mortality ≥5%). It helps determine which patients need further workup such as stress imaging or coronary angiography.
Formula: DTS = Exercise time (min) − 5 × ST deviation (mm) − 4 × Angina Index (0/1/2).
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The patient undergoes a standard Bruce protocol treadmill test with continuous ECG monitoring. Record three key measurements: total exercise time in minutes, the maximum ST-segment deviation observed (depression or elevation in mm), and the angina index (0 = no angina during the test, 1 = angina that did not stop the test, 2 = angina that caused test termination).
Apply the formula: Duke Score = exercise time (minutes) minus (5 multiplied by maximum ST deviation in mm) minus (4 multiplied by angina index). For example: 8 minutes exercise, 2 mm ST depression, non-limiting angina = 8 minus (5x2) minus (4x1) = -6. Negative scores indicate worse prognosis.
Low risk (score ≥+5): annual mortality ~0.25%, 5-year survival 97% — generally reassure and optimize risk factors without further invasive testing. Moderate risk (score -10 to +4): annual mortality ~1.25%, 5-year survival 91% — consider stress imaging or CT coronary angiography. High risk (score <-10): annual mortality ~5%, 5-year survival 72% — coronary angiography is typically recommended.
Cardiologists, internists, sports medicine physicians
The primary use of the Duke Treadmill Score is to integrate the three most prognostic exercise test findings — exercise duration, ST changes, and angina — into a single risk estimate after completing a Bruce protocol exercise stress test.
Cardiologists, internal medicine physicians
High Duke Treadmill Score (<-10) predicts annual mortality ≥5% and warrants coronary angiography for definitive evaluation of coronary artery disease. Patients with high-risk scores rarely benefit from further non-invasive testing — direct catheterization is appropriate.
Emergency physicians, internists, cardiologists
The Duke score is most valuable in patients with intermediate pre-test probability of obstructive CAD — typically middle-aged adults with exertional chest pain, multiple risk factors, or equivocal prior workup. Low scores in this group can safely defer invasive evaluation.
Cardiologists, preventive cardiology specialists
Exercise duration in the Duke score also captures functional exercise capacity in METs (metabolic equivalents). Achieving ≥10 METs (approximately 10 minutes of Bruce protocol) is associated with excellent prognosis independently of other risk factors and can be reassuring even with borderline other findings.
Cardiology nurses, exercise physiologists, cardiologists
A low Duke score after exercise testing can facilitate safe discharge or observation rather than urgent hospital admission. Conversely, a high-risk Duke score supports urgent cardiology evaluation and potential same-day or next-day coronary angiography.
The Duke Treadmill Score was derived and validated using the standard Bruce protocol specifically. If a modified Bruce, Naughton, or other protocol was used, exercise time cannot be directly substituted. Do not apply the Duke score to non-Bruce protocol tests — the time component is protocol-specific.
A Duke score below -10 predicts annual cardiac mortality ≥5% and 5-year survival of only 72%. This risk profile is high enough that proceeding directly to coronary angiography is more efficient than additional non-invasive imaging. Additional stress imaging in high-risk patients does not change the management outcome.
Exercise time (and the METs it represents) is itself a strong, independent predictor of mortality. Each MET increase in exercise capacity reduces cardiovascular mortality by approximately 13-15%. Achieving ≥10 METs on Bruce protocol confers an excellent prognosis regardless of ST changes. Poor exercise capacity (<5 METs) is a red flag even with a normal ECG response.
Exercise ECG has lower sensitivity (~60%) in women compared to men (~70%) for detecting obstructive CAD, in part due to different pre-test probability distributions and hormonal influences on ST changes. Functional stress imaging (nuclear perfusion or stress echocardiography) has higher diagnostic accuracy in women and should be considered for intermediate-risk women.
A stress test is considered diagnostic only if the patient achieves ≥85% of age-predicted maximum HR (220 minus age). A submaximal test (HR <85% max) is non-diagnostic for ischemia because peak myocardial oxygen demand may not be reached. The Duke score from a submaximal test has lower predictive value.
Exercise-induced ST depression in aVR or posterior leads (V7-V9) is more specific for left main or proximal LAD ischemia than isolated inferior or lateral ST changes. ST elevation during exercise in non-infarct territory is particularly concerning and may indicate severe proximal stenosis with transmural ischemia.
Patients with complete left bundle branch block (LBBB), left ventricular hypertrophy with repolarization changes, digoxin effect, or Wolff-Parkinson-White (WPW) syndrome cannot be evaluated with exercise ECG stress testing for ischemia. These patients require nuclear perfusion imaging or stress echocardiography. Do not calculate Duke score if baseline ECG makes ST analysis unreliable.
Patients on beta-blockers may be unable to reach target heart rate during stress testing, potentially producing a non-diagnostic (submaximal) test. Options include exercising the patient on medications (still provides functional capacity data and prognosis) or holding beta-blockers for 48-72 hours before testing if the primary goal is diagnostic (discuss with ordering physician).
Heart rate recovery — the decrease in HR during the first minute after exercise cessation — is a complementary prognostic marker. Abnormal heart rate recovery (decrease <12 bpm in 1 minute) is associated with increased mortality independent of the Duke score and should be documented alongside DTS for comprehensive exercise test interpretation.
Duke Treadmill Score developed by Mark et al. (NEJM 1991) from 2,758 patients undergoing exercise testing at Duke University Medical Center. Annual mortality: score <-10 (5.25%), -10 to +4 (1.25%), ≥+5 (0.25%). 5-year survival: high-risk 72%, moderate 91%, low 97%. C-statistic 0.78 for mortality. Validated in women by Alexander et al. (NEJM 1998). ACC/AHA Exercise Testing Guidelines (Fletcher et al., Circulation 2001) include Duke score as class I recommended risk stratification tool. External validation in contemporary PCI era by Kwok et al. (JACC 1999).
Your Duke Treadmill Score places you into one of three prognostic categories. A score of 5 or higher indicates low risk, with an annual cardiac mortality rate below 1% and a 5-year survival of approximately 97%. These patients generally do not require further invasive testing. A score between -10 and +4 indicates moderate risk, with annual mortality of 2-3%. Additional workup such as stress echocardiography, nuclear perfusion imaging, or coronary CT angiography may be appropriate. A score below -10 indicates high risk, with annual mortality of 5% or greater, and coronary angiography is typically recommended.
The score integrates exercise capacity, ischemic burden (ST deviation), and symptom severity into a single prognostic index. A low score driven primarily by poor exercise capacity has different clinical implications than one driven by marked ST depression, so the individual components should also be considered in clinical decision-making.
Use the Duke Treadmill Score after a standard exercise treadmill test (Bruce protocol) to help stratify patients with suspected or known coronary artery disease. It is most useful for intermediate-risk patients being evaluated for stable chest pain or exertional symptoms where the pre-test probability of significant CAD is neither very low nor very high.
The score is particularly valuable in settings where stress imaging is not immediately available, as it helps determine which patients can be safely managed conservatively and which need further workup. It is also used in cardiology guidelines to guide the decision between medical therapy and invasive evaluation.
The Duke Treadmill Score was validated using the standard Bruce treadmill protocol. If a different exercise protocol was used, the exercise time component may not be directly comparable. The score also assumes that ST-segment changes are interpretable — it should not be applied to patients with baseline ST abnormalities from left bundle branch block, left ventricular hypertrophy with repolarization changes, digitalis use, or pre-excitation syndromes.
The DTS was derived and validated predominantly in male patients with suspected CAD. Its accuracy may be lower in women and in populations with low prevalence of obstructive CAD. It does not account for additional stress test findings such as exercise-induced arrhythmias, blood pressure response, or heart rate recovery, which also carry prognostic significance.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
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