Lichtman, J.H., Froelicher, E.S., Blumenthal, J.A., Carney, R.A., Doering, L.V., et al. (2014). Depression as a risk factor for poor prognosis among patients with acute coronary syndrome: Systematic review and recommendations: A scientific statement from the American Heart Association. Circulation, 129, 1350-1369.
There are about 15.4 million US adults with coronary heart disease. About 20% of those hospitalized for an acute coronary syndrome (ACS; that includes myocardial infarction or unstable angina) meet diagnostic criteria for major depression. An even larger percentage of those with heart disease show sub-clinical levels of depressive symptoms. As I reported in the June 2014 PPRNet Blog about 4% of the population suffer from depression, and so the rates of depression are substantially higher among those with ACS. There is a large body of research showing a reliable association between depression and increased morbidity and mortality after ACS. The goal of this scientific statement by the American Heart Association is to review current evidence for the role of depression as a risk factor among patients with ACS. The authors were particularly interested in studies looking at: (1) all cause mortality, (2) cardiac mortality, and (3) composite outcomes including mortality and nonfatal events. Fifty three studies, representing tens of thousands of patients were included in the review. Twenty one of 32 published studies indicated that depression is a risk factor for all-cause mortality after ACS. Fewer studies looked at the relationship between depression and cardiac mortality, but 8 of 12 studies suggested that depression is a risk factor for cardiac mortality after ACS. Finally evidence from 17 of 22 studies suggested that depression was a risk factor for combined outcomes of cardiac mortality, all cause mortality, and nonfatal cardiac events. The authors also reported on meta analyses looking at the association between depression and mortality following myocardial infarction. Depression increased the risk in individuals of mortality from 1.6 to 2.3 times. The authors concluded that the American Heart Association should elevate depression to the status of a risk factor for adverse medical events in patients with ACS.
This scientific statement by the American Heart Association published in a technical journal read by cardiologists is important because it acknowledges a mental health problem as a risk factor for mortality from a common medical disease. The evidence is quite strong that depression increases the risk of death in those with heart disease, especially acute coronary syndrome (ACS). Some of the mechanisms for the risk may include genetic/physiological factors like inflammation, platelet aggregation, and the serotonin system that are associated with both depression and ACS. In addition, depression can result in less physical activity and poorer self care which could exacerbate a number of health problems that increase the risk for cardiac disease. Depression is also associated with increases in high risk health behaviors like smoking, sedentary lifestyle, and non-adherence to medical treatment. Assessing for and treating depression among patients who have a history of or are at risk of heart disease is important. If such a patient is depressed or has elevated depressive symptoms, then the depression should be treated in order to reduce the risk of death due to medical problems. In the July 2014 PPRNet Blog, I reported on a network meta analysis showing the positive effects of 7 psychotherapies for depression.