A pitfall in electrocardiographic diagnosis. Acute pulmonary embolus versus actue high lateral infarction.

A patient presented in the coronary care unit with acute chest pain and in shock. The electrocardiographic features suggested an acute high lateral myocardial infarction. Certain features were, however, paradoxical, and suggested reversed arm electrodes. A repeat electrocardiogram reflected the classic features of acute pulmonary embolism. It is evident that the "mirror image' of the classic S1Q3T3 presentation of acute pulmonary embolism mimics an acute high lateral infarction.