We found that trait scores of anxiety (STAI-T), and education level were associated with a higher risk of mortality after adjusting for medical factors and postdischarge major cardiac events during 7.5 years of follow up after cardiac surgery.
Psychosocial risk factors, such as low socio-economic status, chronic family or work stress, social isolation, negative emotions (e.g., chronic depression or acute anxiety), and negative personality patterns, such as Type-D-pattern or hostility, have been shown to be significantly associated with the development of coronary artery disease and with the occurrence of adverse outcome in patients with established coronary artery disease .
Numerous studies have underlined the importance of preoperative depression and anxiety for mortality after cardiac surgery [2, 15, 16]. Although anxiety and depression are highly co-morbid and tend to share risk factors, anxiety is a discrete emotional experience. Anxiety has been characterized as a future-oriented, negative affective state with a component of fear, resulting from the perception of threat and the individual’s perceived inability to predict, control, or obtain the desired results in upcoming situations. Symptoms of anxiety may be adversely associated with a high risk of ischemic heart disease , and anxiety has been associated with an increased risk of myocardial infarction and fatal ischemic heart disease after CABG .
Depression is a prevalent comorbidity in patients with coronary artery disease. The prevalence ranges from 14–47% with higher rates seen most often in patients with unstable angina or those awaiting CABG surgery . Depression on the day before surgery and depression that persists months after surgery were associated with a two- to threefold increased risk of mortality . According to a recent study about women at high risk for cardiovascular disease not only the presence of depression but also the severity of depression influenced the outcome jointly with or independent of known risk factors . Further research is needed to find the factors responsible for constant high STAI-T and BDI scores. On the other hand, survivors were more frequently treated than those who died during the follow-up.
In a parallel analysis of preoperative anxiety and depression, only anxiety was significantly associated with increased mortality after adjusting for known mortality risk factors . We have used the additive EUROSCORE for risk estimation for cardiac surgery . The addition of anxiety and education to the risk model might help to further refine the risk factors associated with increased mortality. We found that preoperative STAI-T scores were associated with increased 7-year mortality, and these results highlight the importance of preoperative screening for anxiety in routine clinical practice. In a similar study, patients who had major depression in the hospital just before discharge were more than twice likely to die or be readmitted for cardiac causes in the 12 months after discharge from the hospital than those without this disorder. They also found that major depressive disorder increased the frequency of cardiac events independent of the usual risk factors . These findings suggest that a surgically successful cardiac operation does not always correlate with the improvement of individual life expectancies after surgery  and does not decrease level of depressive symptoms .
The overlap between anxiety and depression has long been discussed. Most recent research on the pathophysiological links between negative emotions and ischemic heart disease has revealed that depression and anxiety have several similar effects on coronary events, including increased catecholamine levels, indicators of autonomic dysfunction (increased heart rate, decreased heart rate variability, and decreased baroreceptor sensitivity), increased platelet activity, and subacute chronic inflammation . Low education and income are important determinants of all-cause mortality and cardiovascular mortality  among patients with myocardial infarction. Low income and education are related to a higher risk profile and poorer treatment . In accordance, in our study, a higher level of education was associated with a longer survival time. Patients with a high level of education are likely to have a higher income and therefore can afford the more expensive “healthy” diet and sport activities .
The limitation of our study is the small sample size and thus the lower statistical power. Nevertheless, the applied statistical method strengthened the results of this study. However, it was a single center study; hence, the results may not be generalizable to similar patient populations. Furthermore, we have excluded patients who could not fill out our questionnaires and those undergoing emergent surgery or a concomitant procedure, suggesting that our results may not necessarily generalize to higher risk patients. Smoking history, actual blood pressure and medication after discharge were not recorded during the follow-up period. Additionally, we cannot exclude the possibility that the data for the non-responders could have changed the results. The strengths of this study are that in addition to anxiety, education has also been evaluated. Also, this study has a long-term follow up, and the data were collected prospectively. The model created and validated in this study can have an important clinical impact, as it provides a preoperative estimate of an individual patient’s risk of death. We have enrolled patients undergoing CABG and/or valve surgery, which can also influence our results, although a previous report did not find significant in-hospital differences in mortality and morbidity .