DALLAS, Oct. 16, 2001 -- A class of antidepressants called selective serotonin reuptake inhibitors (SSRIs) was associated with a lower heart attack risk in a study of smokers, according to new research in Circulation: Journal of the American Heart Association.

The SSRIs in the study included fluoxetine (Prozac), fluvoxamine (Luvox), paroxetine (Paxil) and sertraline (Zoloft).

Until now, studies have suggested that depression may be a risk factor for heart disease and is linked to a higher probability of death after a heart attack. Today's study is the largest of its kind to examine whether SSRIs prescribed for depression lowered the risk of a first non-fatal heart attack. In evaluating the potential benefit of SSRIs, investigators theorized that the drugs might protect the heart the same way aspirin does, by reducing blood clotting and inhibiting platelet clumping. Platelets are disc-shaped blood components that stick together to form a blood clot. The majority of heart attacks are caused by blood clots.

In the study, investigators compared people in an eight-county region around the Philadelphia metropolitan area who were hospitalized for a first heart attack (653 people) with a randomly selected group of people who had no history of a prior heart attack (2,990 people). All patients in both groups were smokers. The study was primarily designed to test the value of nicotine patches in preventing heart attacks. However, it also collected detailed information on the use of antidepressants and assessed the association between heart attack and the drugs. Patients were studied over a 28-month period and were between the ages of 30 and 65 years old.

Of the 143 SSRI users identified, 87 percent said they were taking the drugs for depression; 3.5 percent for anxiety and 9.1 percent for unknown reasons or other indications.

"We found a 65 percent reduction in risk of a heart attack among SSRI users compared to nonusers," says Stephen E. Kimmel, M.D., the study's senior investigator and assistant professor of medicine and epidemiology at the University of Pennsylvania in Philadelphia. "This is the largest study to show such an association."

Kimmel acknowledged that the study could not distinguish between whether there was a beneficial effect of treating depression or whether the SSRI's pharmacological effects contributed to the reduced risk. A drawback of the study is that researchers did not use validated depression scales, which are used to assess depression.

Kimmel was quick to add that this is just a single study and that the results need to be confirmed. However, "We think there is something unique about SSRIs above and beyond the treatment of depression," he says.

The researchers say the pharmacological effects of these drugs, particularly their effect on reducing blood clots, are a likely contributing factor to the lower heart attack risk.

Additionally, the investigators say that other studies have shown that using another class of antidepressants; such as the tricylic antidepressants, in patients with heart problems might be harmful, causing abnormal heart rhythms and more heart attacks.

Although the results are provocative, the data are preliminary. "The ultimate test would be using a randomized controlled trial study, but that would have to be very large," Kimmel says. "Examining the effects of other antidepressants is also needed."

Study co-authors include William H. Sauer, M.D., and Jesse A. Berlin, Sc.D.

---American Heart Association

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