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Heart Disease Health Center

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Lasting Damage From Fen-Phen Drug?

Study Shows Lingering Heart Valve Problems in Former Users of Banned Obesity Drugs Fenfluramine and Dexfenfluramine
WebMD Health News
Reviewed by Louise Chang, MD

Nov. 5, 2008 -- Two banned obesity drugs may have lingering effects on the heart, according to a new study.

The study shows that heart valve problems linked to the banned obesity drugs fenfluramine and/or dexfenfluramine typically last years after stopping those drugs.

The FDA ordered fenfluramine and dexfenfluramine off the market in September 1997 after those drugs were linked to heart valve problems. Fenfluramine was one of the ingredients in "fen-phen," and dexfenfluramine is closely related to fenfluramine. The "phen" in fen-phen refers to a drug called phentermine, which wasn't banned.

The new study, published online today in BMC Medicine, shows what happened to the hearts of 5,743 former users of fenfluramine and/or dexfenfluramine.

Heart Valve Problems

The patients were seen by doctors including Charles Dahl, MD, of the Central Utah Clinic in Provo, Utah, between July 1997 and February 2004.

During that time, each patient got an echocardiogram and 1,020 patients got two or more echocardiograms 30 months apart, on average.

Dahl's team searched the echocardiograms for signs of blood leaking back through heart valves (regurgitation), and they noted which patients got surgery to correct heart valve problems.

When the study started, nearly 20% of the women and almost 12% of the men had at least mild regurgitation through the aortic valve or moderate regurgitation through the mitral valve.

Those conditions were more likely in women and people who had used fenfluramine and/or dexfenfluramine for longer periods of time.

Follow-up echocardiograms showed that aortic and mitral regurgitation usually stayed about the same or worsened, but improved in some cases.

Why would some cases worsen and others improve? That's not clear from the study.

But the researchers note that they saw evidence of "early improvement, followed by relative stabilization with only slightly more individuals showing improvement over the longer term as compared to deterioration."

Heart Valve Surgery

Thirty-eight patients -- less than 1% -- got heart valve surgery. Such surgery wasn't common, but it was more common than in the general public, and in 25 cases, heart valve damage was linked to the drugs, according to Dahl's team.

Three of the four researchers who worked on the study, including Dahl, have served as expert witnesses for plaintiffs in lawsuits related to fen-phen. Those lawsuits are over and the researchers declare that they don't have any current financial conflicts of interest.

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