Diagnostic Methods Coronary Artery Disease

We have developed computer algorithms that enable epicardial potential distributions to be calculated from electrocardiographic body surface data. To validate this inverse transformation we obtained body surface maps during the ST segment in 55 patients with acute infarction who subsequently underwent coronary arteriography and we constructed epicardial ST segment potential distributions for each patient. From the unlabeled epicardial maps one of us predicted the coronary artery that would be found to be involved in the infarction. These predictions were compared with the results of coronary arteriography and this showed that the analysis of the epicardial map correctly predicted the coronary artery involved in 40 of 55 patients (72.7%). In another eight patients the anatomy was partially predicted. In the 15 patients in whom the prediction was incorrect or partially correct (27.3%), 11 had critical disease or occlusions of the predicted coronary artery but the infarct-related artery was incorrectly identified. This verifies that sensible epicardial potential maps can be calculated from body surface electrocardiographic data, and that these data are sufficiently accurate to predict the vessel involved in acute infarction. Circulation 76, No. 6, 1282-1289, 1987. THE NEED for a noninvasive measure of size and position of myocardial infarction has been well recognized. 1 2 A technique that would meet some of the criteria for clinical use would be to examine the epicardial potentials during the ST segment in the patients with acute infarction. Clearly it is not possible to do this directly, but a method based on a mathematical transformation of body surface electrocardiographic data back onto the heart surface might provide equivalent data. We have developed a system of electrocardiographic body surface mapping designed to rapidly acquire electrocardiographic data in patients with acute myocardial infarction.3 In addition, an algorithm has been developed that enables epicardial potential distributions to be calculated from the measured body surface data4-6 by use of detailed models of the torso based on geometric data obtained from computed tomographic From the Department of Medicine, University of Tasmania, Hobart, Tasmania, Australia. Funded by the Australian National Health and Medical Research Council, the Clive and Vera Ramaciotti Foundation, the National Heart Foundation of Australia, and the Royal Hobart Hospital Research Trust. Address for correspondence: Dr. David Kilpatrick, Department of Medicine, University of Tasmania, 43 Collins St., Hobart, Tasmania 7000, Australia. Received April 21, 1987; revision accepted Aug. 6, 1987. scans. With these models, relationships between epicardial potentials and body surface potentials are derived. These relationships are inverted by mathematical regularization techniques. Various torso models can be used. It is difficult to validate directly the epicardial potentials that are calculated. This would require simultaneous measurement of body surface and epicardial potentials in an intact human torso. A study of this type has been done in dogs,7 but there are obvious ethical and practical difficulties with undertaking this kind of study in a human subject. To test the validity of our calculated epicardial potential distributions, we have examined data from a series of patients with acute myocardial infarction who have also undergone coronary arteriography. From the calculated epicardial potential distributions during the ST segment, we have predicted the vessel involved in the infarction. These predictions have then been compared with the arteriographic data.