Comprehensive cardiac research has included meta-analyses detailing etiological and prognostic associations between depression, in particular, and CAD outcomes.,
Recent depression research among CABG surgery patients are described in . Several earlier studies corroborate the association between depressive symptoms upon mortality in the longer term.,
In a study of 309 patients at one year follow-up, Connerney et al.
reported that major depression, but not depressive symptoms, were associated with cardiac events. The authors found a more than two-fold greater risk for cardiac events [risk ratio = 2.31, 95% confidence interval (CI) 1.17–4.56] after adjustment for ejection fraction, female, gender, extended length of hospital stay, New York Heart Association class and number of revascularized vessels and living alone. Follow-up of these patients at ten years showed both depression symptoms and major depression increased the risk for cardiac mortality. A similar finding attributable to depression symptoms was reported by Blumenthal et al.
who excluded patients with a major depression and psychiatric diagnosis, but nevertheless found that moderate to severe depression symptoms were associated with increased mortality risk (hazard ratio = 2.4, 95%CI 1.2–4.2). Evidence also extends to non-fatal morbidity outcomes, where depression symptoms reportedly increase the risk for unplanned hospital readmissions,,–
and poorer quality of life.
Scheier et al.
reported depressive symptoms associated with surgery, CAD and wound infection resulted in hospital readmissions among 309 patients at six month follow-up. Patients reporting depressive symptoms one month after cardiac surgery were found to have a greater proportion of arrhythmias and return of angina symptoms at five year follow-up.
In a study of 963 CABG patients, improvements in physical health at six month follow up were lower among patients with depressive symptoms after adjustment for cardiac severity and baseline health.
A systematic comparison of depression, anxiety and stress suggested that only depression was consistently associated with quality of life domains tapping into vitality, social role functioning, physical and general health.
Association between depression and mortality or cardiac outcome after cardiac surgery.
Depression sub-types have also been investigated. Extrapolating whether the timing and course of depression influences post-CABG morbidity, some evidence supports that new onset,
and persistent vs.
remitted depression symptoms assessed by self-reporting questionnaires
pose a greater risk for mortality and cardiac morbidity than brief periods of depression at the time of surgery. With respect to specific clusters of depression symptoms, two recent studies support a prognostic association between cognitive depression symptoms (e.g., pessimism, past-failure, self-criticalness, worthlessness) with nearly a two-fold greater risk of cardiac morbidity and mortality after CABG surgery.,
These findings curiously suggest that the adverse effects of depression after CABG are independent of any somatic depressive symptoms, or medical related co-morbidity. However, current evidence summarized by Carney and Freedland
generally does not confirm that any particular subtype of depression confers greater CAD morbidity risk.
Depression appears to contribute only partly to increased risk for subsequent morbidity after CABG surgery. Not surprisingly, research also implicates anxiety in CABG surgery outcomes,–
as depression and anxiety frequently occur in the same individual concurrently and across the lifespan. A study among 62,665 CABG patients showed that 9% of cases with co-morbid PTSD and major depression diagnosis had a greater risk of in-hospital mortality than patients with either PTSD, or major depression alone.
However, electronic medical records were employed for a limited range of psychiatric disorders that were not verified with structured psychiatric interview. By contrast, studies that simultaneously assessed both depression and anxiety symptoms, reported that each negative emotional state portended nearly two-fold increased risk of unplanned hospital readmissions.,
Recently, our group showed pre-operative anxiety was associated with greater all-cause mortality [hazard ratio = 1.88, 95%CI 1.12–3.17] and independent of age, renal disease, concomitant valve procedure, cerebrovascular disease and peripheral vascular disease.
Taking these findings further, we showed that anxiety increases odds for incident atrial fibrillation after CABG surgery.
Additionally, we found that GAD, but not major depression or panic disorder, was associated with acute in-hospital morbidity events, such as stroke, myocardial infarction and renal failure.
Together the results seem to suggest that both depression and anxiety have a role in post-CABG morbidity. However, focusing solely on depression, rather than general psychiatric distress and anxiety, might pose as a barrier to the identification of CABG surgery patients at risk of morbidity and requiring psychological intervention.
Studies to date are not without their limitations. Like depression-CAD studies elsewhere,
lack of adjustment for conventional cardiac risk factors, such as left ventricular function, pose a serious caveat to interpreting the role of psychosocial factors upon post CABG functioning. It is likely that adjustment for non-psychological morbidity risk factors is limited by the low number of actual morbidity events experienced among typically small samples with short follow-up.
Some studies have also excluded patients with a depression or anxiety diagnosis,,
thereby precluding examination of a dose-response effect among the more distressed patients. Unfortunately, these practices tend to bias the results in favor of rejecting the null hypothesis and the resultant wide confidence intervals,,,
obscure the effect of study size and the biological plausibility of an effect for depression and anxiety. Research could be improved by addressing the known risk factors for postoperative morbidity and mortality, such as those identified by the Society of Thoracic Surgeons,
extending the length of patient follow-up, recruiting more patients, and employing structured psychiatric assessments alongside self-reported distress measurements.