March 14, 2005 — Antidepressant drugs may not deserve the blame for the increased heart attack risk seen in some studies of the drugs.increased heart attack risk seen in some studies of the drugs.

Instead, depression — not the drugs that treat it — may explain the pattern, say British researchers. That applies for both older tricyclic antidepressants such as Elavil, Pamelor, and Tofranil and the newer selective serotonin reuptake inhibitors (SSRIs) such as Prozac, Paxil, and Zoloft, they report.

Heart attack risk wasn’t constantly higher with antidepressants, they say, calling that finding “reassuring.”

“We found a transient increased risk of [heart attack] in the initial 28 days of exposure to antidepressant drugs, which did not persist after this period,” write the researchers. “This suggests that people now taking antidepressants do not need to stop taking these drugs, as no increased risk is conferred by prolonged exposure.”

Heart attack risk wasn’t found to be linked to any particular type of antidepressants.

The lack of an association between the type of antidepressants suggest that these associations are more likely due to factors relating to underlying depression and health services utilization than to specific adverse drug effects, they write.

People being treated for depression are advised to consult their doctors with any questions or concerns about their medications.

Depression, Heart Disease Are Widespread

Every year, heart attacks strike more than a million people in the U.S., says the National Heart, Lung, and Blood Institute. About 460,000 of those cases are fatal.

Heart attacks are the most visible sign of heart disease, a leading cause of death for men and women in America.

Depression is also very common in America. Nearly 19 million U.S. adults per year are depressed, says the National Institute of Mental Health.

It’s crucial to get emergency help whenever heart attack symptoms surface and to take proactive steps to curb heart disease. Depression also needs treatment. Counseling, prescription drugs, and lifestyle changes can all help ease depression’s burden.

Studies have found that heart disease and depression sometimes go hand in hand, but the precise explanation isn’t clear.

With so many depressed people — and such a high rate of heart disease — the British study offers a closer look at heart attacks and antidepressants.

Tracking Heart Attack Risk and Antidepressants

The data came from more than 60,000 people who had had their first heart attack from 1988 through 2001. The cases were recorded in a British database of more than 8 million people.

Each heart attack patient was compared with six similar people in the same database who had not had a heart attack. Prescription records showed which people had taken antidepressants.

The researchers wanted to see whether the antidepressants affected heart attack risk, whether the risk differed between types of antidepressants, and whether the risk changed over time with antidepressants.

Heart attacks occurred around age 70, on average. Most heart attack patients (61%) were men. As expected, smoking, high blood pressure, diabetes, and increased BMI (body mass index) were all heart attack risk factors.

Heart Attack Risk Subsides

Antidepressants were associated with an increased risk of heart attacks. But it wasn’t quite that simple.

Taking all risk factors into account, both tricyclic antidepressants and SSRIs were associated with an increased risk of a person’s first heart attack. But the risk was higher for the first 28 days on either type of antidepressant. After that, the risk subsided, rising again for 29-56 days after the patients stopped taking antidepressants.

“Reassuringly … there was no increased risk of [heart attack] with prolonged antidepressant exposure,” says the study.

The researchers say they’re not sure why the risk rose after patients stopped taking the drugs. They say it could be due to the drugs, but it could also be that patients quit the drugs as their heart problems worsened or developed other illnesses. More work is needed to sort that out, say the researchers, who included Laila Tata of England’s Nottingham City Hospital.

Their study appears in the April edition of the journal Heart.