Electrocardiographic manifestations: Patterns that confound the EKG diagnosis of acute myocardial infarction-left bundle branch block, ventricular paced rhythm, and left ventricular hypertrophy

The 12-lead electrocardiogram (EKG), at powerful tool used in evaluating th e chest pain patient, has its shortcomings. One such failing is encountered in a patient with one of the following electrocardiographic patterns: left bundle branch block (LBBB), ventricular paced rhythm (WR), and left ventri cular hypertrophy (LVH). These patterns reduce the ability of the EKG to de tect acute coronary ischemic change and acute myocardial infarction (AMI), Several strategies are available to assist in the correct interpretation of these complicated electrocardiographic patterns, including a knowledge of the ST segment-T wave changes associated with these confounding patterns, p erformance of serial EKGs, and comparison with previous EKGs if available. This article suggests guidelines and interpretive tools for diagnosing AMI on EKG in patients with these confounding patterns. (C) 2000 Elsevier Scien ce Inc.