Interpreting results of exercise studies after acute myocardial infarction altered by thrombolytic therapy, coronary angioplasty or bypass. Numerous studies have assessed the ability of exercise modalities to predict patient outcome after acute myocardial infarction (AMI). Implicit in the use of these prior data to assess the prognosis of patients currently undergoing exercise studies is the assumption that patients selected for exercise assessment are similar over time and that the data generated in the past are therefore applicable to the current patient populations. This study retrospectively assessed the clinical, exercise, and rest and exercise radionuclide angiographic data in 791 consecutive patients referred for exercise radionuclide angiography within 1 month after AMI during a 5-year period to determine if the clinical and exercise characteristics of patients referred for exercise evaluation after infarction have changed significantly over time. Most parameters examined demonstrated significant increasing trends, including thrombolytic therapy at the time of AMI, revascularization procedure between AMI and exercise assessment, age, beta-blocker usage, Q-wave AMI, inferior infarction, exercise double product, exercise capacity, significant ST-segment depression with exercise, peak ejection fraction, and change in ejection fraction with exercise. These data indicate that the characteristics of patients selected to undergo exercise after AMI in a large referral center have changed significantly over time. If these data are applicable to other referral centers and to other exercise testing modalities, previously published results regarding exercise assessment after AMI will need to be reconfirmed in patients currently selected for testing, since these results may no longer be applicable in this current era of aggressive medical and interventional management. 