Effects of Mental Stress on Myocardial Ischemia During Daily Life

OBJECTIVE: To determine the relative risk of myocardial ischemia triggered by specific emotions during daily life. DESIGN AND SETTING: Relative risk was calculated by the recently developed case-crossover method, in which the frequency of a presumed trigger during nonischemic, or control, hours is compared with the trigger's frequency during ischemic, or case, hours. Outpatients at Duke University Medical Center, Durham, NC, underwent 48 hours of ambulatory electrocardiographic (ECG) monitoring with concurrent self-report measures of activities and emotions. Occurrences of negative emotions in the hour before the onset of myocardial ischemia were compared with their usual frequency based on all hours in which ischemia did not occur. SUBJECTS: From a sample of 132 patients with coronary artery disease and recent evidence of exercise-induced ischemia who underwent 48 hours of ambulatory ECG monitoring, 58 patients exhibited ambulatory ischemia and were included in the analysis. OUTCOME MEASURES: Myocardial ischemia during 48-hour ECG monitoring was defined as horizontal or downsloping ST-segment depression of 1 mm (0.1 mV) or more for 1 minute or longer compared with resting baseline. The ECG data were cross-tabulated with subjects' concurrent diary ratings of 3 negative emotions-tension, sadness, and frustration-and 2 positive emotions-happiness and feeling in contro-on a 5-point scale of intensity. RESULTS: The unadjusted relative risk of occurrence of myocardial ischemia in the hour following high levels of negative emotions was 3.0 (95% confidence interval CI, 1.5-5.9; P<.01) for tension, 2.9 (95% CI, 1.0-8.0; P<.05) for sadness, and 2.6 (95% CI, 1.3-5.1; P<.01) for frustration. The corresponding risk ratios adjusted for physical activity and time of day were 2.2 (95% CI, 1.1 -4.5; P<.05) for tension, 2.2 (95% CI, 0.7-6.4; P=.16) for sadness, and 2.2 (95% CI, 1.1-4.3; P<.05) for frustration. CONCLUSIONS: Mental stress during daily life, including reported feelings of tension, frustration, and sadness, can more than double the risk of myocardial ischemia in the subsequent hour. The clinical significance of mental stress-induced ischemia during daily life needs to be further evaluated.