The value of electrocardiographic R-wave changes in exercise testing: Preexercise versus postexercise measurements.

To determine the usefulness of R-wave amplitude changes during exercise testing for the diagnosis of coronary artery disease (CAD) and to understand the discrepancies that have been described in the literature regarding their value, we studied two groups of patients by means of electrocardiographic (EKG) treadmill testing and coronary arteriography. Group I was composed of 149 patients who were studied prospectively. The specificity of R-wave changes measured from preexercise to immediately postexercise (SRV(5)) was 81%, but that of R-wave changes measured from preexercise to peak exercise (URV(5)) was 46%. A group of 156 patients (Group II) evaluated retrospectively showed a high specificity for the SRV(5) (84%) and poor specificity for the URV(5) (39%). The sensitivity of the SRV(5) was 38% in Group I and 42% in Group II. Therefore, if measured during the immediate postexercise period and not at peak exercise, changes in R-wave amplitude may be of value in the diagnosis of coronary artery disease by electrocardiographic exercise testing.