Anxiety and depression after coronary artery bypass graft surgery: most get better, some get worse

Dr Barbara Murphy, Principal Research Fellow, Heart Research Centre, Melbourne, Australia
barbara.murphy@heartresearchcentre.org

Many researchers and clinicians are currently relying on in-hospital or pre-admission depression status as an indicator of ongoing depression risk, as well as later mortality risk, in cardiac patients, including those admitted for acute myocardial infarction (AMI) or to undergo coronary artery bypass graft surgery (CABGS). However, recent research suggests that early depressive symptoms do not persist for all who experience them. Moreover, not all cardiac patients with early depression are at increased mortality risk in the years that follow. For example, a recent study by James Blumenthal and colleagues from Duke University demonstrated that patients whose in-hospital depression resolved by six months after their cardiac event were at no greater mortality risk than non-depressed patients. In contrast, patients whose depression persisted at six months were at twice the mortality risk as those whose depression resolved (1).

In the present study of 184 CABGS patients (2), early depression scores did not give a good indication of patients' likely depression trajectory. Many patients who reported high pre-admission depressive symptoms went on to improve in the months after discharge, albeit incompletely. Other patients who reported few or no pre-admission depressive symptoms worsened in subsequent months. At the two month post-event assessment, around 25% of patients had depression scores at or around the cut-off for mild to moderate depression (3). However, not all of those patients had continuing depression: about half were on a trajectory of improvement, while half were on a trajectory of decline. How do we determine whether a patient with an elevated depression score is likely to worsen or improve? More importantly, how do we distinguish ‘at risk' patients as they are admitted to hospital?

The present paper (2) goes some way towards doing this, highlighting patients with more severe disease as being at increased risk of worsening depression, even in the absence of a high depression score at their first assessment. Unpartnered patients, smokers, patients with high anxiety, high cholesterol, angina, and previous bypass surgery had an increased likelihood of pre-admission depression and, although they tended to follow the trajectory of improving depression, did not show complete resolution of their depression by six months post-event. Perhaps these patients would show continuing improvement in subsequent months? Without an additional follow-up, our study was unable to confirm likely trajectories of depression in the longer term.

Further studies with larger samples and longer follow-up periods are needed to continue to investigate the likely trajectories of depression after cardiac surgery and other cardiac events, and to identify patients at risk of poor outcomes in terms of both persistent depression and increased mortality risk. Nonetheless, the findings of this study have important implications for improving health care practice in relation to the identification of ‘at risk' patients, and the subsequent targeting of interventions for those most in need of support.

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1. Blumenthal JA, Lett HS, Babyak MA, White W, Smith PK, Mark DB, Jones R, Mathew JP, Newman MF. Depression as a risk factor for mortality after coronary artery bypass surgery. The Lancet 2003; 362:604-609.
2. Murphy BM, Elliott PC, Higgins RO, Le Grande MR, Worcester MUC, Goble AJ, Tatoulis J. Anxiety and depression after coronary artery bypass graft surgery: most get better, some get worse. European Journal of Cardiovascular Prevention and Rehabilitation 2008;15:434-440.
3. Snaith RP, Zigmond AS. The Hospital Anxiety and Depression Scale - Manual. Windsor, UK: NFER-Nelson; 1994.

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