Sept. 7 (HealthDay News) -- Certain depressed patients who suffer from heart disease have nearly double the risk of dying over a seven-year period compared with other depressed patients, researchers say.

The patients most at risk are those who suffer from the most severe depression within a few weeks of being hospitalized for a cardiac event, such as a heart attack, and those whose depression doesn't get better within six months, according to study findings published in the September issue of Archives of General Psychiatry.

The study authors noted that about one out of every five people who survive a heart attack hit a patch of major depression over the next few weeks. Depression has been known to boost the risk of death after an acute coronary syndrome event, such as heart attack or the chest pain known as unstable angina.

In the new study, Dr. Alexander H. Glassman of Columbia University Medical Center and the New York State Psychiatric Institute in New York City and colleagues examined the medical records of 361 participants in a study of antidepressant use after heart attack.

Regardless of whether the patients took antidepressants, those whose depression didn't improve within six months were more likely to die: 15.6 percent of those whose depression improved died, compared with 28.4 percent of those who had little or no improvement, the researchers reported.

"Depression is a syndrome with multiple pathways to a similar clinical picture. In patients with active coronary heart disease, it seems likely that the association with depression is a two-way street, and each can aggravate the other," the study authors concluded.

SOURCE: JAMA/Archives journals, news release, Sept. 7, 2009