The Duke Treadmill Score (DTS) is the gold standard prognostic index for evaluating patients undergoing exercise electrocardiography (stress testing) for suspected coronary artery disease.
Beyond Just "Positive or Negative"
Historically, a stress test was often judged as simply positive (ST depression occurred) or negative. The DTS recognizes that the duration of exercise a patient can tolerate is just as prognostically important as the ECG changes. A patient who develops 1mm of ST depression after 12 minutes of intense exercise has a vastly better prognosis than a patient who develops 1mm of ST depression after only 2 minutes.
DTS = Exercise Time - (5 × ST Deviation) - (4 × Angina Index)
Where:
Exercise Time=
Total time in minutes using the standard Bruce protocol.ST Deviation=
Maximum net ST segment depression in millimeters.Angina Index=
0 for no angina, 1 for non-limiting angina, 2 for test-limiting angina.Interpretation and Triage
The final score directly correlates with 5-year survival rates:
- Low Risk (Score ≥ 5): Excellent 5-year survival (>97%). These patients generally do not require invasive coronary angiography and can be managed medically.
- Moderate Risk (Score -10 to +4): 5-year survival of approximately 90%. Management requires clinical judgment, often leading to further imaging like a nuclear stress test or echocardiogram.
- High Risk (Score ≤ -11): Dismal 5-year survival (~65%) with medical therapy alone. These patients have severe, often multi-vessel or left-main disease and typically proceed directly to cardiac catheterization.