In the ECG of a diabetic patient without coronary artery disease, a double T wave was observed. The ECG was normal the next day. This finding was interpreted as representing repolarization abnormalities (e. g., myocardial ischemia) by many health care workers. However, it represents an artifact called "pseudo double T wave". The cause is unknown but most likely due to abnormalities at the interface between surface electrodes and skin tissue. The diagnosis of ECG artifacts requires meticulous examination of the tracings coupled with a thorough knowledge of normal patterns.
Keywords: Coronary artery disease; Electrocardiographic artifacts; Electrocardiography; Repolarization abnormalities.