Comparison of the electrocardiographic changes induced by maximum exercise testing with treadmill and cycle ergometer

Abstract

The purpose of this study was to assess electrocardiographic changes induced by maximum exercise testing with treadmill and cycle ergometers in patients following myocardial infarction. Forty male subjects were studied; all had experienced a myocardial infarction within the preceding twelve months. Cycle ergometer and treadmill testing were performed on separate days and in random order. Cycle ergometry was performed in the erect position and the initial work load was 100 kpm/min with increments of 100 kpm/min each minute. With treadmill testing the subject walked at a constant speed (80 m/min) throughout the test. The initial work load was a 0% grade and each minute it was increased by 2.5%. The results were that 19 subjects showed ST-segment changes related to exercise. Significant ST-segment depression was observed in 11 subjects with treadmill exercise. In seven of these subjects a similar degree of ST-segment depression occurred also with cycle ergometry. For the eight subjects with ST-segment elevation during exercise a significant and similar changes was observed with both tests. The resolution of ST-segment depression was more rapid than ST elevation. During treadmill testing in all subjects the maximum value of oxygen uptake (VO2) was about 26.5 ml/kg min, the maximum heart rate was 166 beats/min and the maximum systolic blood pressure was 181 mm Hg. With cycle ergometry the maximum value of oxygen uptake was 22.6/kg min, the maximum heart rate was 159 beats/min and the maximum systolic blood pressure was 194 mm Hg. In this study the mean ST-segment depression produced by maximum exercise testing using two dissimilar types of exercise, cycling and incline walking, was comparable, in spite of differences between the two tests as to maximum value of oxygen uptake, heart rate and systolic blood pressure. A number of comparisons have been made between exercise performances on a cycle ergometer and a treadmill. In normal subjects the maximum value of oxygen uptake has been found to be 8-12% higher on a treadmill; the greater disparity in patients with heart disease, amounting to 17% in this study, is unexplained. The magnitude of ST-segment elevation was twice that of ST-segment depression, but it is unlikely that comparable degrees of ST-segment change for both elevation and depression indicate similar degrees of coronary obstruction. (Arrigo-Genoa)