The exercise treadmill test is useful for detecting coronary artery disease in patients with chest pain. However, controversy exists as to the utility of this test in patients with ST segment depression on resting electrocardiography (ECG). Many clinicians turn to the more expensive imaging stress tests when faced with this clinical presentation. Prior studies concerning this issue have been based on a small number of patients and have used visual interpretation of the ECG changes. Fearon and colleagues studied the effect of ST depression on the diagnostic characteristics of the exercise treadmill test in patients with chest pain.
Consecutive patients referred for chest pain evaluation were enrolled in the study. Patients were included in the study if they had no prior history of coronary artery disease. All received resting ECGs that were interpreted visually and by computer. They then received an exercise treadmill test using a standard protocol, followed by coronary angiography. Coronary artery disease was defined as a narrowing of at least 50 percent in at least one of the epicardial arteries. Patients who presented with or without ST segment depression on the resting ECG were compared during the study.
A total of 1,282 patients were enrolled in the study. The sensitivity of the exercise treadmill test increased in patients with ST segment depression determined by visual inspection. The specificity, however, decreased. Using a computer to interpret the ECG improved the specificity and the sensitivity. The predictive accuracy of the exercise treadmill test was no different in the group with ST segment depression than in the group that had no ECG changes.
The authors conclude that this study supports the use of an exercise treadmill test to evaluate patients with chest pain and no history of prior coronary artery disease who have ST depression on ECG. This finding was true regardless of whether the ST depression was assessed visually or by computer. The results of this study indicate that the exercise treadmill test is an effective initial diagnostic test in these patients and may eliminate the need for stress imaging studies.