Frequency of ST-segment depression produced by mental stress in stable angina pectoris from coronary artery disease

Abstract

Physical exertion is a well-documented trigger of transient myocardial ischemia in patients with coronary disease. More recently, studies have shown that mental stress may also be a cause of myocardlal ischemia. The purpose of this study was to examine the relationship of physical activities and perceived mental states to myocardial ischemia while patients were going about their normal dally activities. Twenty-eight patients with documented coronary artery disease underwent ambulatory monitoring of the electrocardiogram. Physical activity and perceived mental status were recorded by patients in a diary which was then graded according to intensity of the activity. Analyses of the continuous electrocardiographic recordings were done separately from the analysis of the diaries. The time of each episode of ischemia, the duration of each episode in minutes and the number of episodes in each 24-hour period were calculated. A total of 372 episodes of ST-segment depression occurred in 912 hours of monitoring. Ischemic events occurring during usual physical and usual mental activities were most frequent (36%). Twenty-six percent of ischemic episodes occurred during increased physical activity, but usual mental activities. Interestingly, 22% of the ischemic events occurred at high levels of mental stress, but low physical activity. Ten percent of episodes occurred during sleep. Although the majority of events occurred during usual dally activities, when duration of ischemia was normalized for time spent in each category, increasing physical or mental activity was associated with an increasing duration of ischemia per unit time (p <0.05). The results of this study suggest that the intensity of both physical and perceived psychological states influences ischemic heart disease activity during daily life.