For this latest study, the researchers followed up more than 750 heart attack patients for a period of five years.
In the five years following a heart attack, 106 patients died. Of those, 62 had been diagnosed with depression, while 44 had not.
All other risk factors such as age, smoking status, hypertension and diabetes were adjusted for.
Lead researcher Professor Robert Carney, from Washington University, said: ‘There is a two-to-four fold increase in a person's risk of dying following a heart attack if they also happen to be depressed.
‘Previously we thought the impact of depression was strongest for the first three to six months following a heart attack and then gradually dropped off within a couple of years.
‘Instead we found that the effect lasts for at least five years.'
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