The current study is designed to have broad generalizability and inform a potential shift toward greater utilization of stress echocardiography with UCA. This will be accomplished by comparing UCA stress echocardiography with myocardial SPECT among hospitalized patients presenting with atraumatic chest pain. This study seeks to demonstrate: clinical comparability of the 2 modalities (based on non-diagnostic test rates), improved care efficiency (based on length of stay), lower costs, improved provider satisfaction, and a presumed improved safety profile through the elimination of radiation exposure.