Relation between localization of coronary artery disease and local abnormalities in ventricular activation during exercise tests

Abstract

To examine whether or not the location of local abnormalities on body surface isochrone maps reflects the site of myocardial ischemia, 48 coronary artery disease patients without myocardial infarction were studied. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously before and after the submaximal treadmill exercise. For each lead, the duration from the QRS onset to the time of the most rapid decrease in QRS voltage was measured (index of ventricular activation [IVA]). Based on the data provided by these 87 leads, IVA isochrone maps (IVA map) in preexercise and in postexercise, as well as IVA maps showing the difference between preexercise and postexercise, were constructed. The IVA was defined as abnormal when it exceeded (mean+2 SD) the normal range. We called the area with the abnormal IVA, the "+2SD area." In patients having a stenosis in the left anterior descending artery, the +2SD area in each map was located mainly on the left anterior chest, whereas in patients having a stenosis in the right coronary artery, the +2SD area in each map was located mainly on the right lower thoracic surface. Moreover, the +2SD area of patients with both left anterior descending and right coronary artery disease appeared on both the left anterior chest and the right lower thoracic surface. In patients with left circumflex artery disease, however, the location of the +2SD area did not suggest a stenotic site because of its small population. On the other hand, it was difficult to determine the ischemic site from the body surface distribution of ST segment depression. The results suggest that local abnormalities on IVA maps have the potential to indicate the ischemic site. The body surface IVA maps can be useful in evaluating the site of myocardial ischemia noninvasively.