Heart Valve Abnormalities 1 Year after Patients Stopped Taking the Weight-Loss Drug Dexfenfluramine

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The summary below is from the full report titled "Natural History of Valvular Regurgitation 1 Year after Discontinuation of Dexfenfluramine Therapy. A Randomized, Double-Blind, Placebo-Controlled Trial." It is in the 20 February 2001 issue of Annals of Internal Medicine(volume 134, pages 267-273). The authors are NJ Weissman, JA Panza, JF Tighe Jr., and JT Gwynne.

What is the problem and what is known about it so far?

Dexfenfluramine and fenfluramine are drugs that limit hunger. These drugs were often combined with another drug called phentermine, a combination known as "fen-phen." In 1997, researchers reported that some patients who had taken fen-phen for weight loss had developed leaks in the valves that control the flow of blood through the heart, a condition known as valvular regurgitation. On the basis of this report, dexfenfluramine and fenfluramine were taken off the market. It is not known, however, whether valve abnormalities change after patients stop taking the drugs.

Why did the researchers do this particular study?

To find out whether dexfenfluramine-associated valve abnormalities change 1 year after patients stop taking the drug.

Who was studied?

This study included 1095 overweight patients who had been in an earlier study that compared the effects of two types of dexfenfluramine (regular and slow-release) with a placebo for weight loss. The placebo looked like dexfenfluramine but contained no active ingredient.

How was the study done?

Patients had echocardiography soon after stopping dexfenfluramine or placebo, and again 1 year later. Echocardiography is a test that uses sound waves to make pictures of the heart; it is an excellent way to look at heart valves. In each patient's echocardiogram, the researchers determined whether regurgitation was present and, if so, how bad it was. Next, they determined whether regurgitation improved, worsened, or stayed the same between each patient's first and second echocardiograms.

What did the researchers find?

Patients had taken dexfenfluramine or placebo in the original study for an average of about 2.5 months. Of 1095 patients in the study, 914 had two echocardiograms. As expected, valve regurgitation was more common on the first echocardiogram of study patients than among patients who had taken placebo. Between the first and second echocardiogram, however, regurgitation in one particular valve (the aortic valve) improved more in the patients who had been taking dexfenfluramine than in those who had been taking placebo. Regurgitation did not change differently over time in any of the other heart valves in dexfenfluramine recipients compared with placebo recipients.

What were the limitations of the study?

This study included patients who had been taking dexfenfluramine for a relatively short time, and it did not include patients who had taken the fen-phen combination. In addition, patients did not have echocardiography before they started taking the drugs, so some valve abnormalities could have existed before the patients took dexfenfluramine.

What are the implications of the study?

Heart valve abnormalities associated with the weight-loss drug dexfenfluramine do not worsen, and some abnormalities may improve, after patients stop taking the drug.