In patients with coronary artery disease (CAD), cardiac function is only marginally associated with health status. Ruo and colleagues sought to determine the relative influence of depressive symptoms and cardiac function on health status, hypothesizing that depressive symptoms would correlate more closely than measures of cardiac function.

A total of 1,024 patients with a history of myocardial infarction or revascularization, or a diagnosis of CAD were enrolled in the Heart and Soul Study. Health status was assessed by measures of symptom burden, functional status, and quality of life, as well as a question on generic health status, in which patients compared their health with others their own age. Depressive symptoms were assessed using the Patient Health Questionnaire, and cardiac function was measured with a resting echo-cardiogram, a stress echocardiogram, and treadmill testing for exercise capacity.

Of these patients, 201 (20 percent) had depressive symptoms. The authors observed a dose-response relationship between depression score and all four measures of health status. In terms of cardiac function, decreased exercise capacity was associated with greater symptom burden, greater physical limitation, worse quality of life, and worse overall health. Resting left ventricular ejection fraction and wall motion score index were not associated with any of the four health status measures.

The authors found that depressive symptoms are associated with health status outcomes, whereas two physiologic measures of disease severity—left ventricular ejection fraction and ischemia—are not. Exercise capacity also predicts health status outcomes but always in association with depressive symptoms. Given the correlation between depression and health status, the authors recommend identifying and treating depression in patients with myocardial infarction and other manifestations of CAD as a means of improving health-related quality of life.