MORNING INCREASE IN HEMODYNAMIC-RESPONSE TO EXERCISE IN PATIENTS WITHANGINA-PECTORIS

The present study was conducted to determine whether or not there is d iurnal variation in the hemodynamic responses to stimuli that increase myocardial oxygen demand, and the effects of such variation on electr ocardiograms (ECG). Fifteen patients with angina pectoris, 17 patients with old myocardial infarction, and 8 healthy controls were examined in this study. Graded exercise stress testing was conducted in the sup ine position, once in the morning and once in the afternoon, using a b icycle ergometer. A standard 12-lead ECG was recorded before, immediat ely after, and 3, 5, and 10 min after the end of the exercise. The exe rcise ECG and blood pressure changes were compared among the groups an d, within each group, the results after morning and afternoon exercise were compared. Hemodynamic responses, including heart rate, blood pre ssure, and the pressure-rate product, showed greater increases in the morning than in the afternoon in angina patients and controls, in asso ciation with greater depression of the electrocardiographic ST-segment . In contrast, patients with old myocardial infarction exhibited no di fference in hemodynamic responses or the ST-pattern from morning to af ternoon. The results suggest that diurnal variation of hemodynamic res ponses to increased oxygen demand may explain, at least partly, why my ocardial ischemia of effort angina is more severe in the morning than in the afternoon.