DURATION AND MAGNITUDE OF ST-SEGMENT DEPRESSION DURING EXERCISE AND RECOVERY - A SYMMETRICAL RELATION

The pattern of appearance and disappearance of ST depression on 12-lead electrocardiographic exercise testing in subjects with coronary artery disease (greater than or equal to 70% stenosis) and its relation to the severity of disease were prospectively explored in 34 consecutive patients. The first lead to show positivity during exercise also developed maximum ST depression in 73% of patients and was the last lead to lose positivity in recovery (94%). The last lead to show positivity during exercise was first to lose positivity in recovery (92%). Greater Si depression was associated with a greater number of positive leads (p < 0.001; r = 0.7). The duration of ST depression during exercise, maximum ST depression, and recovery time were related (p = 0.001, r = 0.6; p = 0.006, r = 6.5; p < 0.001, r = 0.6, respectively, for the three interactions). However, the correlations of ST depression and recovery time with the severity of vessel disease and with rate-pressure product at initial ST depression were poor, suggesting that the degree of ST-segment depression and recovery time may depend-more on the duration and intensity of myocardial ischemia solicited with exercise rather than on the ischemic threshold or on the severity of coronary artery disease.