From the Guidelines
A Duke treadmill score of 6 indicates a low risk for cardiovascular events, suggesting a good prognosis with an estimated 5-year survival rate of approximately 97%. The Duke treadmill score is calculated using exercise time, ST-segment deviation, and exercise-induced angina during a stress test. A score of 6 falls in the low-risk category (scores ≥5 are considered low risk), meaning the patient has a favorable cardiac outlook 1. According to the 2011 ACCF/AHA focused update, a low-risk treadmill score is defined as a score of 5 or greater, which corresponds to a low risk of adverse outcomes 1.
Key Considerations
- The Duke treadmill score has been validated in various populations as predictive of risk, but its elements, such as exercise capacity, ST-segment changes, and exercise-induced angina, have not consistently appeared as risk predictors in all studies 1.
- A nomogram based on simple demographics, easily obtained risk factors, and standard exercise test findings was found to better discriminate risk than the DTS, with a C index of 0.83 versus 0.73 (p<0.001) 1.
- The 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults notes that the DTS does not predict cardiac survival beyond age 75, and elderly patients have a more adverse prognosis than younger patients with the same Duke risk score 1.
Management and Follow-up
No specific medication changes or interventions are typically needed based solely on a Duke treadmill score of 6, though standard cardiovascular risk factor management should continue. Despite this reassuring score, it's essential to consider the entire clinical picture, including symptoms, other risk factors, and additional test results when making treatment decisions. Regular follow-up with a healthcare provider is still recommended, with routine cardiovascular risk assessment every 1-2 years depending on other individual risk factors.
From the Research
Duke Treadmill Score of 6
- A Duke treadmill score of 6 is considered to be in the moderate-risk category, as scores ranging from -10 to +4 are generally classified as moderate-risk 2.
- The Duke treadmill score is a weighted index that combines exercise time or capacity, maximum ST-segment deviation, and exercise-induced angina to predict cardiovascular mortality 3.
- Studies have shown that the Duke treadmill score is associated with cardiovascular mortality, but exercise capacity in metabolic equivalents of task is a superior predictor of poor prognosis 3.
- A score of 6 may indicate some level of cardiovascular risk, but the exact implications depend on individual patient characteristics and other clinical factors.
Comparison to Other Studies
- One study found that patients with high-risk Duke treadmill scores (≤ -11) and normal myocardial perfusion imaging on SPECT had lower cardiovascular event rates compared to those with abnormal SPECT 4.
- Another study compared exercise echocardiography and the Duke treadmill score for risk stratification in patients with known or suspected coronary artery disease and normal resting electrocardiogram, finding that exercise echocardiography had incremental value over the Duke score for predicting outcome 5.
- The relationship between the Duke treadmill score and coronary artery lesion severity, as well as the need for revascularization, has also been investigated, with results suggesting that the Duke treadmill score is associated with significant coronary artery stenosis and cardiac revascularizations 2.