A 69-year-old male patient with type 1 diabetes mellitus had been under treatment at our outpatient clinic since the age of 65. He had previously undergone surgery for esophageal cancer at the age of 55; the excised portion of the esophagus was replaced by a retrosternal gastric tube. He was admitted to our hospital for suspected pneumonia on April 8, 2004. An electrocardiogram (ECG) on admission showed marked ST depression in leads V1 and V2, and prominent negative T waves in leads I and aVL; however, the T waves unexpectedly flattened after 2 minutes and the ST depression resolved after about 4 hours. On January 7, 2005, we performed a deep breathing test to analyze the effects of movements of the thoracic wall and intrathoracic structures on the ECG. In this test, deep inspiration induced ST depression reaching 0.5 mV in leads V1 to V3; this resolved on switching to deep expiration. ECG changes together with chest computed tomography images supported the concept that the ST-T abnormalities were induced by cardiac compression caused by expansion of the gastric tube between the sternum and heart. We have reviewed 7 other similar reported cases.