The same terminology applicable for describing the location of an AMI at necropsy is applicable for defining its location by electrocardiogram. Certain terms used electrocardiographically, namely "inferior", "diaphragmatic," and "true posterior," should be avoided because their opposites are not used. Ideally, a proper description of the location of an AMI should include defining its involvement in all the dimensions of the left ventricle (considered as a cone): the portion of the walls of the circle involved (anterior, posterior, lateral, and septal); the amount of the wall's thickness involved (transmural or nontransmural [subendocardial]), and the portions of the wall's length involved (basal half or apical half or both). Certain portions of the walls of both the left and right ventricles are rare sites of AMI, and knowing these sites helps in more precisely defining by ECG the location of the AMI. AMI involving the anterior wall of the left ventricle rarely is limited to just its basal half; and, therefore, anterior AMI, for practical purposes, indicates involvement of at least the apical half of the ventricle. AMI involving the basal half of the posterior left ventricular wall, in contrast, is common, but the ECG is not accurate in differentiating posterobasal from posteroapical AMI. Furthermore, the ECC provides no specific pattern to indicate AMI of the ventricular septum, lateral wall of the left ventricle, either posterior or anterolateral walls of the right ventricle, or papillary muscle. AMI of the right ventricle virtually never occurs with "anterior" AMI of the left ventricle. In contrast, nearly 25% of patients with "posterior" transmural AMI also have associated AMI involving at least the posterior wall of the right ventricle.