Exercise testing early after myocardial infarction. Risks and benefits.

Submaximal exercise testing in the early weeks following myocardial infarction appears to be safe in selected patient groups. Potential benefits of such testing includes: (1) promotion of patient self-confidence, (2) determination of post-hospital exercise prescription, (3) detection of arrhythmias, and (4) determination of post-hospital prognosis. However, the practical value of the apparent psychologic benefits and of the exercise prescription information in a patient not participating in formal exercise rehabilitation therapy is unclear. Detection of potentially important arrhythmias appears to be more adequately effected with 24-hour ambulatory electrocardiography, and detection of such arrhythmias appears to add relatively little prognostic information to that available from exercise electrocardiographic S-T analysis, or from resting radionuclide ejection fraction. Nonetheless, exercise-induced S-T segment depression can provide potentially useful prognostic information regarding morbid or fatal events during the year after infarction. Moreover, recent data suggest that exercise-induced angina and/or S-T segment depression can aid importantly in the noninvasive determination of the anatomic extent of coronary artery disease. The additional benefit or radionuclide cineangiographic determination of left ventricular function during exercise and of thallium 201 scintigraphic determination of myocardial perfusion during stress remain to be defined, although both approaches appear to provide important prognostic information. However, despite the potential benefits of exercise testing, in the absence of clinical trials of available therapy in the "high risk" patient defined by exercise testing, there remains an ill-defined relationship between the information available from exercise testing and the results of management decisions based on this information.