Duke Treadmill Score

The Duke Treadmill Score (DTS) is a clinical tool used to predict the risk of coronary artery disease (CAD) and to assess the prognosis of patients undergoing an exercise stress test. It is particularly useful in evaluating patients with suspected ischemic heart disease.

History

The Duke Treadmill Score was developed at Duke University in the 1980s as a means to improve the diagnostic and prognostic value of the exercise stress test. It was designed to provide a more quantitative assessment of the risk of coronary artery disease and to guide clinical decision-making.

Calculation

The Duke Treadmill Score is calculated using the following formula:

DTS = Exercise time (minutes) - (5 × ST deviation in mm) - (4 × Angina index)

• Exercise time is measured in minutes on a standard Bruce protocol treadmill test.
• ST deviation refers to the maximum ST-segment deviation (either depression or elevation) in millimeters observed during the test.
• Angina index is scored as follows:
  • 0 = No angina
  • 1 = Non-limiting angina
  • 2 = Exercise-limiting angina

Interpretation

The Duke Treadmill Score stratifies patients into three risk categories:

• Low risk: DTS ≥ +5
• Intermediate risk: DTS between -10 and +4
• High risk: DTS ≤ -11

Low Risk

Patients with a low-risk Duke Treadmill Score have an excellent prognosis, with an annual mortality rate of less than 1%. These patients may not require further invasive testing and can often be managed with lifestyle modifications and medical therapy.

Intermediate Risk

Patients with an intermediate-risk score have a moderate risk of coronary events. Further evaluation with imaging studies such as myocardial perfusion imaging or coronary angiography may be warranted to better assess the extent of coronary artery disease.

High Risk

High-risk patients have a significantly increased risk of cardiac events, with an annual mortality rate exceeding 3%. These patients often require more aggressive investigation and management, including consideration for coronary revascularization procedures.

Clinical Use

The Duke Treadmill Score is widely used in clinical practice to guide the management of patients with suspected coronary artery disease. It helps in decision-making regarding the need for further diagnostic testing and the intensity of therapeutic interventions.

Limitations

While the Duke Treadmill Score is a valuable tool, it has limitations. It may not be applicable to patients unable to perform an adequate exercise test or those with baseline electrocardiogram abnormalities that preclude accurate ST-segment analysis. Additionally, it does not account for other clinical factors such as age, gender, or comorbidities that may influence the risk of coronary artery disease.

See Also

• Exercise stress test
• Coronary artery disease
• Bruce protocol

External Links

• American College of Cardiology
• American Heart Association