There appears to be a link between clinical depression and cardiovascular health. In the United States, clinical depression (defined as particularly severe depression lasting a significant amount of time) is diagnosed in roughly 10 percent of physically healthy people. By contrast, it is diagnosed in about 20 percent of heart patients with no history of heart attack, and up to 65 percent of heart patients who have had a heart attack. Research studies continue to investigate the links between clinical depression and cardiovascular health. Findings from these studies include:

• In initially healthy individuals, the onset of clinical depression can predict the development of heart disease. Even moderate levels of depression have been linked to the development of high blood pressure.
  
  
• The progress of atherosclerosis appears to be tied to clinical depression. A 2004 study found that the more severe the atherosclerosis, the more strongly it appears tied to depression later in life.
  
  
• Depression and diabetes are an especially dangerous combination. Patients who are suffering from both are 20 to 30 percent more likely to die than patients with depression alone.
  
  
• Overall mortality six months after a heart attack is higher in depressed patients than in those who are not depressed. The mortality risk is estimated to be nearly 5 times greater for depressed patients.
  
  
• Depression at one month following coronary artery bypass surgery has been seen to predict other cardiac events (e.g., angina) up to five years later.
  
  
• Among patients with heart failure, depression can increase the risk of re-hospitalization and mortality by 50 percent. This risk has shown to be independent of standard risk factors such as age, New York Heart Association Class and ejection fraction.

Not only can clinical depression increase the likelihood of developing or dying from a heart problem, but a heart problem can also increase the likelihood of clinical depression. Many patients feel sadness, a loss of control, insecurity about scars from a heart-related surgery, a loss of youth and other feelings that spiral into clinical depression. These feelings are real and in no way reflect weakness or failure. Depressed patients are urged to seek treatment as soon as possible.