[Stress and ischemic heart disease]

The role of mental stress in ischemic heart disease is two-fold: as a risk factor of coronary artery disease and as a trigger of acute ischemic attacks in patients with established coronary atherosclerosis. The role of stress as a risk factor is still controversial. Data regarding the relationship between occupational factors and development of coronary atherosclerosis have not been confirmed. A type personality, above all when anger and hostility traits are present, seems to be a predisposing factor for the development of coronary artery disease. These data however, were not confirmed in study groups including patients with a higher prevalence of other, more important, risk factors. Stress can have an important role as a trigger of acute ischemic attacks. This is indirectly shown by the circadian distribution of the main manifestations of ischemic heart disease (sudden death, myocardial infarct, ST segment depression). In fact, their incidence is significantly higher in the morning hours, after awakening, when mental stress is higher. In the laboratory setting, mental stress can induce myocardial ischemia in a variable percentage of patients (0 to 80%). Prevalence of mental stress-induced myocardial ischemia varies depending on the stressor used, the patients group and, above all, the diagnostic tool. Ischemic episodes induced by mental stress, in fact, are generally silent and less severe and extensive than those elicited by exercise stress testing. It is therefore often necessary to use methods, such as myocardial scintigraphy, with higher sensitivity for the detection of myocardial ischemia in comparison with ECG. Patients with mental stress-induced myocardial ischemia tend to present higher scores on measures of aggressivity, anger and hostility. These psychological features are related to a hightened cardiovascular reactivity with a brisk and greater increase in heart rate and blood pressure after exposure to stress. It would be therefore useful to identify patients with such a behaviour by psychological assessment and/or analysis of sympatho-vagal balance by analysis of heart rate variability. The mechanism by which mental stress can induce myocardial ischemia is represented by an increase in myocardial oxygen demand, through the increased heart rate and blood pressure, probably associated with an increase in coronary vascular resistance. This last phenomenon is likely caused by small coronary vessel constriction mediated by alpha-adrenergic activation and by a reduced EDRF release by the damaged endothelium.