QRST integral analysis of body surface electrocardiographic mapping for assessing exercise-induced changes in the spatial distribution of local repolarization properties in patients with coronary artery disease and in patients with previous anterior infarction

We studied resting, postexercise, difference (postexercise - rest) QRST iso integral maps, and the correlation coefficient between resting and postexer cise. maps. Study I Fifteen controls and 48 patients without previous myoca rdial infarction were studied. In coronary syndrome X group (n = 14), no pa tients showed an abnormally negative area on the postexercise map. In coron ary ST depression group (n = 26), 12 patients (46%) showed an abnormally ne gative area on the postexercise map, and the correlation coefficient was lo w. Although all control, syndrome X, and coronary ST depression patients sh owed the global-downward type of difference map, coronary ST elevation pati ents (n = 8) showed the right-downward and left-upward type, right-upward a nd left-downward type, or reversed saddle type. Coronary ST depression is r elated to a globally marked decrease in local repolarization forces. Corona ry ST elevation is associated with multidirectional changes in local repola rization forces. Study II Fifty-one patients with previous anterior infarct ion (29 with residual ischemia and 22 without) were studied. The incidence of the global-positive type of maps was increased and that of the saddle-ty pe map was decreased from rest to postexercise in both groups. The global-u pward type or right-downward and left-upward type of difference map was obs erved in both groups, but the reversed saddle type, right-upward and left-d ownward type, or global-downward type was observed in the residual ischemia group (34%, 24%, and 14%, respectively). Residual ischemia causes multidir ectional changes or a global decrease in local repolarization forces. In bo th studies, multidirectional changes in local repolarization forces may be related to the vulnerability to ventricular arrhythmias.