What does the DTS (Decision Tree Study) study recommend?

Duke Treadmill Score (DTS) Study: A Prognostic Tool for Cardiovascular Risk Assessment

The Duke Treadmill Score (DTS) is an excellent prognostic tool in symptomatic women, with a low DTS being associated with an annual mortality rate of ≈0.25% in contrast to an annual mortality rate of ≈5% in those with a high-risk DTS, with lower mortality rates among women than men. 1

What is the Duke Treadmill Score?

The DTS is a validated risk stratification tool that integrates multiple parameters from an exercise treadmill test (ETT) to improve diagnostic and prognostic accuracy. The formula is:

DTS = Exercise time − (5 × ST-segment deviation) − (4 × angina score index)

Where:

• Exercise time is measured in minutes on the standard Bruce protocol
• ST-segment deviation is the greatest net ST-segment deviation in any lead (except aVR)
• Angina score index: 0 = no angina, 1 = non-limiting angina, 2 = exercise-limiting angina

Risk Stratification Categories

The DTS categorizes patients into three risk groups:

• Low risk: DTS ≥5
• Moderate risk: DTS -10 to 4
• High risk: DTS ≤-11

Clinical Significance and Recommendations

Diagnostic Value

• In symptomatic women referred for ETT followed by coronary angiography, significant coronary stenosis (≥75%) was present in:
  • 19% of low-risk women
  • 35% of moderate-risk women
  • 89% of high-risk women 1

Prognostic Value

• Low DTS: Associated with an annual mortality rate of approximately 0.25%
• High-risk DTS: Associated with an annual mortality rate of approximately 5% 1
• The DTS is a valuable tool for predicting the risk of future myocardial infarction

Management Algorithm Based on DTS

1. Low-risk DTS (≥5):

   • Low annual mortality rate (≈0.25%)
   • Generally can be managed conservatively

2. Moderate-risk DTS (-10 to 4):

   • Should be referred for additional risk stratification with stress imaging study 1
   • Consider further evaluation with stress echocardiography or myocardial perfusion imaging

3. High-risk DTS (≤-11):

   • High annual mortality rate (≈5%)
   • Consider direct referral for coronary angiography

Gender Differences

• The DTS has diagnostic and prognostic value in both women and men 1
• Women generally have lower mortality rates than men within the same DTS category
• The DTS may be less effective at predicting prognosis in elderly women (aged ≥75 years) 1

Important Considerations

• The quoted mortality rates are derived from earlier patient cohorts; contemporary cohorts would likely have lower high-risk mortality rates 1
• Exercise capacity (measured in METs or time) is one of the strongest predictors of outcomes for women 1
• Women who achieve <5 METs are at increased risk of death and related IHD events, independent of traditional cardiac risk factors 1

Limitations and Pitfalls

• Exertional chest pain symptoms were less accurate for detection of obstructive coronary artery disease in women 1
• The DTS should be interpreted alongside other important prognostic variables from the ETT, including:
  • Exercise capacity
  • Chronotropic response
  • Heart rate recovery
  • Blood pressure response 1

Conclusion

The DTS provides valuable risk stratification that goes beyond the ST-segment response alone. It should be calculated and reported for all exercise treadmill tests to guide clinical decision-making regarding the need for additional testing or interventions based on cardiovascular risk.