Isointegral Analysis of Body Surface Electrocardiographic Mapping for Assessing Exercise-Induced Changes in Repolarization Properties in Patients with Coronary Artery Disease

To assess the exercise-induced changes in repolarization properties in patients with coronary artery disease, we analyzed body surface ECG mapping. The patients studied had a normal resting 12-lead ECG and were divided into 2 groups: group A (n = 15; coronary artery narrowing [?], exercise thallium defect [?], ST depression 0.1 mV [?]) and group B (n = 17; [+], [+], [+]). All patients in group B showed significant area (< ?10 ?V?s) in the postexercise ST-T isointegral map. Of the patients in group B, 10 (59%) showed significant area in the postexercise QRST isointegral map and 15 (88%) showed “?2SD area (less than mean ?2SD values in group A)” in the difference map between resting and postexercise QRST isointegrals. The correlation coefficient between resting and postexercise QRST isointegrals in 87 lead points was significantly lower in group B (0.28 ± 0.56) than in group A (0.91 ± 0.06, P < 0.001). Our results indicate that patients with ischemic ST depression have a greater decrease in the QRST isointegral values in the precordial region than patients without ischemia and ST depression. There are also low similarities between resting and postexercise QRST isointegral maps. We conclude that ischemic ST depression is related to the dispersion of the exercise-induced changes in repolarization properties.