DiagnosticsThe electrocardiogram in the ACS patient: high-risk electrocardiographic presentations lacking anatomically oriented ST-segment elevation

ST-segment elevation myocardial infarction (STEMI) is defined as pathologic ST-segment elevation occurring in at least 2 anatomically contiguous leads in a patient with a clinical presentation consistent with acute myocardial infarction (AMI); these findings can suggest the need for urgent revascularization. Unfortunately, the electrocardiogram (ECG) may be nondiagnostic in a large portion of patients who initially present with AMI; furthermore, it is now recognized that ECG patterns that do not meet the traditional diagnostic criteria for STEMI may represent significant AMI-these patterns are generally referred to as the STEMI equivalent patterns in that they are caused by occlusion of an epicardial coronary artery, place significant portions of the left ventricle in jeopardy, and can result in a poor outcome if not recognized and treated appropriately.