Study Confirms Relationship of Diet Drug to Heart Damage

From the WebMD Archives

Nov. 22, 1999 (Baltimore) -- A new study supports what some studies have suggested in the past: the diet drug dexfenfluramine (Redux) does cause damage to heart valves. A similar but not identical drug, fenfluramine (Pondimin), was often prescribed with phentermine in the drug combination known as 'fen-phen.' The makers of fenfluramine and dexfenfluramine voluntarily took them off the market once heart problems were suspected.

This is the first study to convincingly show that this association was related to dexfenfluramine alone, says author Bruce Shively, MD, associate professor of cardiology at Oregon Health Sciences University. "Other studies have looked at people treated for a very short period of time with dexfenfluramine, but our study population was unique in that it was truly representative of the millions of patients in the United States who took dexfenfluramine," he said in an interview with WebMD. Another recent study had failed to find any association with heart valve problems.

The study, which was published in the Nov. 23 issue of the journal Circulation, a publication of the American Heart Association, looked at 412 people. One group had taken Redux and another group had not, but other characteristics of the subjects, such as age, sex, and weight, were matched. The group that had taken the drug had done so for an average of about seven months.

Echocardiography, a technique for visualizing the structure of the heart using sound waves, was performed on each person, and the results were reviewed by three cardiologists for the presence and severity of valve problems in the heart.

Valves are four structures in the heart that keep the blood flowing in one direction. When some of the blood flows backward through a valve, it is called regurgitation. Two of these valves, the mitral valve and the aortic valve, showed mild to moderate defects in more people who had taken Redux than in those who had not. "The study strongly suggests that dexfenfluramine is associated with valve disease," Shively says. "However, the frequency is not very high and the severity is usually mild."

The study also showed that as more time passed after stopping the drug, fewer valve problems were seen. "This indicates the possibility of regression," says Shively.

Elyse Foster, MD, director of echocardiography at the University of California, San Francisco, reviewed the study for WebMD. She says, "The logical next step is serial studies in those with valve regurgitation to determine if there is further regression. The study is also reassuring in that there was no severe disease in this group. However, follow-up studies will be important to determine whether there is progression of disease in those affected patients."

Vital Information:

  • A new study confirms that the diet drug dexfenfluramine (Redux) sometimes causes mild damage to the heart valves.
  • Patients who had been off of the drug for a longer time period had fewer detected valve problems, suggesting that improvement had occurred.
  • Further research should be done to determine whether heart valves continue to improve with time in these patients.