Utility and Safety of Immediate Exercise Testing of Low-Risk Patients Admitted to the Hospital for Suspected Acute Myocardial Infarction

Abstract

More than 2 million patients are admitted to U.S. hospitals annually for clinical suspicion of acute myocardial infarction (AMI), and > 70% are found not to have had a cardiac event. This study evaluates the safety and efficacy of immediate exercise testing for patients admitted to the hospital for suspected AMI. Ninety-three nonconsecutive low-risk patients admitted to the hospital from the emergency department to rule out AMI underwent exercise treadmill testing using a modified Bruce protocol immediately on admission to the hospital (median time < 1 hour). Twelve patients had positive exercise electrocardiograms, 6 of whom had significant coronary narrowing by angiography. An uncomplicated non-Q-wave AMI was diagnosed in 1 patient. Fifty-nine patients had negative and 22 patients had nondiagnostic exercise electrocardiograms. Of these 81 patients, 44 were discharged immediately after exercise testing, 17 were discharged within 24 hours, and 20 were discharged after 24 hours of observation. There were no complications from exercise testing. There were 2 late noncardiac deaths and 1 late AMI. Thus, immediate exercise testing of low-risk patients with chest pain who are at sufficient risk to be designated for hospital admission is effective in further stratifying this group into those who can be safely discharged immediately and those who require hospitalization.