title: Spatial R wave amplitude changes during exercise: relation with left ventricular ischemia and function.
abstract: Thirty patients who exhibited increased and 65 patients decreased spatial R wave amplitude during exercise testing were compared for left ventricular function and ischemic variables. Spatial R wave amplitude was derived from the three-dimensional Frank X, Y, Z leads using computerized methods. All patients had stable coronary artery disease and they were classified into two groups: one that attained a higher (n = 48) and one a lower (n = 47) median value of maximal heart rate during exercise (161 beats/min). Within these two groups, patients with increasing or decreasing spatial R wave amplitude during exercise were analyzed for differences in oxygen consumption, exercise-induced changes in spatial R wave amplitude, ST segment depression laterally (ST60, lead X), ST displacement spatially, left ventricular ejection fraction at rest, change in left ventricular ejection fraction with exercise and thallium-201 ischemia during exercise. Significant differences were demonstrated only in exercise-induced spatial R wave amplitude changes (p less than 0.0001). There was no significant correlation between exercise-induced change in heart rate and change in spatial R wave amplitude in either the group with increasing or the group with decreasing spatial R wave amplitude. It is concluded that changes in spatial R wave amplitude during exercise are not related to ischemic electrocardiographic or thallium-201 imaging changes or to left ventricular ejection fraction determined at rest or during exercise.
mesh_terms: D003327:Coronary Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging; D004562:Electrocardiography; D005080:Exercise Test; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D005082:Physical Exertion; D011868:Radioisotopes; D011877:Radionuclide Imaging; D013318:Stroke Volume; D013793:Thallium
chemical_list: D011868:Radioisotopes; D013793:Thallium