Reliability of Single-Lead and Multiple-Lead Electrocardiography during and after Exercise

Abstract

To define the number, type, and criteria for interpretation of electrocardiographic leads yielding the most reliable results during and after exercise, 203 men were studied. Twelve-lead exercise electrocardiograms (including lead CM 5 ) 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 V 5 , V 6 , 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 V 5 and multiple leads were not significantly different (84 percent [67/80] and 82 percent [71/88], respectively). The highest predictive values were in lead 2 (88 percent; 37/42) and lead V 4 (88 percent; 45/51). Sensitivity was inversely related to the degree of ST-segment depression required for abnormality. Specificity was directly related. Predictive value was directly related in all except leads V 4 and CM 5 . A predictive value of 100 percent was manifested by the various leads with the following amounts of ST-segment depression: lead V 3 , ≥ 2 mm; leads V 4 , V 6 , and aVF, ≥ 3 mm; and lead V 5 , ≥ 4 mm. Even with ST-segment depression of 4 mm or more, lead CM5 had only 83 percent predictive value. Using analysis with multiple leads, all patients with abnormal findings on maximal exercise tests of less than six minutes in duration had significant disease.