BODY-SURFACE ECG POTENTIAL MAPS IN ACUTE MYOCARDIAL-INFARCTION

An algorithm for the early detection of acute myocardial infarction (M I) using body surface electrocardiographic potential mapping has been developed. The mapping system consists of a 64-hydrogel electrode harn ess applied rapidly to the anterior chest, from which electrocardiogra phic signals are stored on a memory card and processed by computer. At each of the 64 points, QRS and ST-T isointegrals and 10 other feature s of the QRST segment are measured. Using these measurements, new vari ables are derived that express the shape of the three-dimensional geom etric surface of the map. The isointegrals, features, and shape variab les are used in a variety of techniques to discriminate between MI and control subjects. Maps were recorded from 69 patients al initial pres entation of chest pain suggestive of acute MI and from 80 healthy cont rol subjects. Using a multiple logistic regression technique, 14 varia bles were identified that correctly classified 79 of the 80 control su bjects (specificity, 98.8%) and 65 of the 69 MI patients (sensitivity, 94.2%). The algorithm based on these 14 variables was applied prospec tively to maps recorded on a further 48 control subjects and 59 patien ts with acute MI. Of the MI patients, 31 had inferior, 13 inferoposter ior, 10 anterior, 2 posterior, 1 lateral, 1 inferior with right bundle branch block, and 1 anterior non Q wave MI. The algorithm correctly c lassified all 48 control subjects (specificity, 100%) and 57 of the 59 MI patients (sensitivity, 96.6%). Marked differences in the three-dim ensional geometric map surfaces between the control subjects and MI pa tients were demonstrated. Variables derived from these surfaces form t he basis of an algorithm with a high sensitivity and specificity for t he automated detection of acute MI. The design of adaptive algorithms and their application to patients with chest pain and atypical electro cardiographic changes, particularly ST depression, may lead to the ear lier detection of MI and greater numbers of patients receiving thrombo lytic therapy.