High levels of depressive symptoms are common among heart disease patients. Rather than a side effect of heart problems, depression may be a serious risk factor.
A recent review of research found that depression after acute coronary syndrome (blocked blood flow to heart) was associated with all-cause death, heart-related death and non-fatal negative outcomes.
The authors of this review recommended that the American Heart Association should officially recogize depression as a risk factor for negative medical outcomes in heart disease patients.
The lead authors of this review were Co-Chairs of the American Heart Association Judith H. Lichtman, PhD, MPH, and Erika S. Froelicher, RN, MA, MPH, PhD, FAHA.
The review included 53 previously published studies on the association between depression and heart disease published before July 24, 2011.
A total of 32 studies assessed the association between all-cause death and depression, 12 studies evaluated heart-related death and depression, and 22 studies considered multiple outcomes, such as death and nonfatal events, and depression.
The findings varied more than expected between studies in terms of demographic makeup, inclusion criteria, assessment of depression, length of follow-up and the outside factors considered.
Still, the authors concluded that depression was a significant risk factor for negative outcomes in people with acute coronary heart syndrome.
The authors believe that depression may affect heart-related outcomes in ways that involve high-risk health behaviors such as smoking, sedentary lifestyle and delay in seeking treatment.
These authors also suggested a couple ways that acute coronary syndrome and depression may be linked inside of the body, such as irregular heartbeat and dysfunction between central nervous systems and hormone release.
Previous research has also shown an association between depression and level of cognitive (basic mental functioning) impairment due to decreased blood flow in and out of the heart among heart disease patients. The authors of this review explained that this impairment could limit physical activity and make it hard for patients to take care of themselves — both of which are connected to depression.
These authors suggested that cardiologists should get guidance about depression screening and treatment.
“The findings didn’t surprise us,” co-author Robert M. Carney, PhD, said in a press statement. “Many studies have reported that depression predicts increased mortality, but it’s rare to delve into this kind of research as deeply and as carefully as we have. Although we suspected we would find this link, having gone through all of these studies and conducted such a careful evaluation, we are more confident than ever that depression is a risk factor for mortality in people who have heart disease.”
The authors noted a few limitations of their research. First, studies in which the findings were deemed inconclusive and in the "grey area" were not included. Second, only studies written in English were considered. Third, there was limited information available for each study, so the interpretation of study characteristics, methods and outcomes may have been incorrect or biased.
Additionally, the studies were published over several decades and the definitions and treatments of acute coronary heart syndrome and depression changed many times. Lastly, the studies were restricted to cases of acute coronary syndrome.
This review was published on February 24 in Circulation.
The American Heart Association provided funding.