Acute posterior wall myocardial infarction: Electrocardiographic manifestations

Myocardial infarction (MI) of the posterior wall of the left ventricle involves occlusion of either the left circumflex or the right coronary artery. Posterior wall MI most often occurs along with acute inferior or lateral MI; isolated posterior wall MI, however, does occur, Electrocardiographic abnormalities suggestive of acute posterior wall MI include the following (in leads V-1, V-2, or V-3): (1) horizontal ST segment depression; (2) a tall, upright T wave; (3) a tall, wide R wave; and (4) an WS wave ratio greater than 1.0 (in lead V-2 only), Further, the combination of horizontal ST segment depression with an upright T wave increases the diagnostic accuracy of these two separate electrocardiographic findings. The additional-lead electrocardiogram using left posterior thorax leads is potentially helpful; ST segment elevation greater than 1 mm in this distribution suggests an acute posterior wall MI. (Am J Emerg Med 1998;16:409-413 Copyright (C) 1998 by W.B. Saunders Company).