U. S. researchers on Monday said that depression increases the risk of people with heart disease developing heart failure even if they take antidepressants.

Heidi May, an epidemiologist at the Intermountain Medical Center in Murray, Utah, and lead author of the study said, "Our data suggest that depression is an important and emerging risk factor for heart failure among patients with coronary heart disease."

Although this finding was expected as previous studies had shown that depression is three times more common after a heart attack and depressed patients are at higher risk of a second heart attack, the unexpected finding was the treatment with antidepressant drugs did not reduce the risk of heart failure among people with depression.

The researchers said the study is the first to look at whether depression raises the risk for heart failure, and they studied nearly 14,000 people with clogged heart arteries. At the time of diagnosis none of them had heart failure or depression and when they checked heart failure rates among the 1,377 people who eventually developed depression, the researchers found much higher rates than among those who were not depressed.

Among those who did not develop depression the heart failure rate was 3.6 % per 100 people, while it was 16.4 % in the group that did. Despite many of the patients taking antidepressants, the heart failure risks did not reduce.

"This finding may indicate that antidepressants may not be able to alter the physical or behavioral risks associated with depression and heart failure, despite a potential improvement in depressive symptoms," May said.

"I was surprised about that," May added. "Since antidepressants reduce the symptoms of depression, you would think that they would decrease the risk of heart failure."

This study should help physicians realize that there is increased danger for people with heart disease and depression, even if they take medicine that reduces the symptoms of depression May said. Earlier studies have shown that such people are less likely to follow recommendations of correct diet and exercise and doctors need to be alert and emphasize the need to stick to the recommendations.

May said the findings suggest that although symptoms of depression may improve, the heart risks related to depression might not. May added that the same kind of study should be done "in other patient populations to see if the results will be replicated."

Dr. Redford Williams, director of the Behavioral Medicine Research Center at Duke University said, " the study leaves open the possibility that other interventions, such as behavioral therapy, might have an effect," he said. "That is pure speculation on my part. But cognitive behavioral therapy, which teaches patients coping skills to deal with negative thoughts, might be effective."

The study is in the April 21 issue of the Journal of the American College of Cardiology.