Reliability of single-lead and multiple-lead electrocardiography during and after exercise.

To define the number, type, and criteria for interpretation of elecfrocardiographic leads yielding the most reliable results during and after exercise, 203 men were studied. Twelve-lead exercise electrocardiograms (including lead CM5) and coronary arteriograms were correlated. Depression of the S-T segment that was present only during exercise was of doubtful significance. Analysis of ECGs after exercise revealed that only leads v5, v6, and CM5 had acceptable sensitivity (61, 53, and 60 percent, respectively). Analysis with multiple leads increased the sensitivity of exercise tests to 65 percent. Lead V5 correctly identified 39 percent (17) of the 44 patients with single-vessel disease and 74 percent (49/66) of those with multiple-vessel disease. The predictive values of interpretations based on lead V5 and multiple leads were not significantly different (84 percent [67/801