Depression can double the risk of death or repeat heart disease in heart attack patients, according to two reviews of more than 40 studies that examine the link between depression and heart disease. The reviews are published in the journal Psychosomatic Medicine.
In the first analysis of 22 studies, patients who were depressed after their heart attacks had a twofold increase in the risk of dying or suffering a new heart problem two years after their heart attack, according to Joost van Melle, M.D., and colleagues of University Hospital Groningen in the Netherlands.
In the second analysis of 20 studies by Jürgen Barth, Ph.D., of University of Freiburg in Germany and colleagues, the researchers concluded that depressed patients were twice as likely to die within two years after their first heart disease episode compared with non-depressed patients.
According to van Melle, post-heart attack depression is common, affecting nearly 20 percent of all heart attack patients.
The two research teams found that the relationship between depression and a higher risk of death and disease stayed consistent despite a variety of ways to measure depression.
The finding "may have important clinical implications for the identification of post-heart attack patients with poor prognosis, because questionnaires are easier, faster and cheaper than psychiatric interviews," van Melle says.
In their study, van Melle and colleagues also noticed a stronger link between depression and higher risk of death in studies published before 1992.
"It may be possible that improvements in cardiac care for hospitalized and rehabilitating heart attack patients are responsible for this finding, but this would need further research," van Melle says.
Both research teams also say they are unsure exactly how depression relates to poor health and greater risk of death in these patients.
"It must be taken into account that sicker patients may have an increased risk to become depressed and subsequently have a worse cardiovascular prognosis. In other words, it is possible that the observed risk is in reality caused by poor cardiac function," van Melle says.
The van Melle study was supported by the Netherlands Heart Foundation.