A model that incorporates clinical variables and exercise testing results predicted mortality better than a score based on exercise testing alone did.
Researchers sought to improve the accuracy of treadmill testing for predicting long-term survival by combining test results with clinical and historical variables. They prospectively studied 33,268 patients with normal electrocardiograms and without known heart disease who were undergoing stress testing for suspected coronary artery disease at a major U.S. medical center.
During a median follow-up of 6 years, 5% of patients died. According to Duke exercise treadmill scores (based on functional capacity, electrocardiographic evidence of ischemia, and test-induced angina pectoris), 19% had intermediate risk and <1% had high risk. In a multivariable model in which clinical and historical variables and test results were considered, significant predictors of death were older age, male sex, smoking, diabetes, lower exercise capacity, abnormal heart rate recovery, and frequent ventricular ectopy during test recovery. Concordance between scores based on this model and actual mortality was better than concordance based on Duke treadmill scores alone. The model was better than Duke scores at correctly classifying people who in fact were at low or high risk, and it discriminated well in a validation set of patients at another medical center.
Comment: A score that incorporates readily available clinical variables and exercise testing results predicted long-term mortality in people with suspected coronary artery disease. As the authors suggest, including such prediction in exercise testing reports could be informative. A mortality probability calculator is available free of charge.
— Richard Saitz, MD, MPH, FACP, FASAM
Published in Journal Watch General Medicine January 10, 2008
Lauer MS et al. An externally validated model for predicting long-term survival after exercise treadmill testing in patients with suspected coronary artery disease and a normal electrocardiogram. Ann Intern Med 2007 Dec 18; 147:821.