Rehabilitation of the Exercise Electrocardiogram

Evaluation of the electrocardiographic ST-segment response to exercise has been the most widely used laboratory method for the assessment of ischemic heart disease for half a century. The availability, accessibility, and relatively simple technological requirements of exercise electrocardiography make it a useful tool for the general internist as well as the subspecialist, but the limitations of standard test criteria are well recognized. Sensitivity for the detection of coronary disease is poor, particularly when only modest obstruction is present, and test responses are often indeterminate in the presence of upsloping ST-segment depression [1, 2]. As an inevitable consequence of low sensitivity and imperfect specificity for coronary obstruction, the positive predictive value of the standard exercise test is poor when disease prevalence is low [3]. This Bayesian principle has become so entrenched in the contemporary medical literature that the perception has evolved that the exercise electrocardiogram cannot be improved and that attempting to improve it is presumptuous.

This perception is wrong, but the exercise electrocardiogram is in need of rehabilitation. It is time to rethink its overall role for the routine evaluation of patients and for specific diagnostic purposes in a range of highly specific populations. As the exercise test is reexamined, there is little reason why the test's performance should be constrained by empirically derived criteria that have been based on visual estimation of ST-segment depression since mid-century. Progress in exercise testing requires development of new criteria with improved sensitivity and specificity, and it is reasonable to expect the exercise electrocardiogram to play a useful and fundamental role in the diagnostic evaluation of chest pain, the assessment of disease severity, and the prediction of risk for coronary events.

The performance of exercise test criteria can vary strikingly with the diagnostic purpose of …