Study Finds Low Rate Of Heart Valve Disease Among Phen-Fen Users

October 1, 1999
Journal of the American College of Cardiology/MedscapeWire

People who took the popular diet drug combination phen-fen (phentermine and fenfluramine) have a low incidence of heart valve disease — comparable to similar people who never took the drugs, according to a new study appearing in the October issue of the Journal of the American College of Cardiology.

"In contrast to some previous reports, we found no evidence of a high rate of valvular disease among people who took phen-fen," said Dr. Andrew J. Burger, of the Beth Israel Deaconess Medical Center in Boston.

The diet drugs fenfluramine and its close chemical cousin dexfenfluramine were withdrawn from the market 2 years ago after researchers reported that a large number of people who took the drugs appeared to have developed diseased heart valves. The early studies, which were uncontrolled, found potential valve problems in as many as 38% of people taking the drugs. Since then, different studies have produced conflicting results, though no study has yet found a significant number of patients who have developed symptomatic heart valve disease.

Dr. Burger and colleagues studied echocardiograms of 226 people who had been taking phen-fen as part of a large clinical trial. The echocardiograms were evaluated by 2 independent echocardiographers.

Significant aortic valve disease and mitral valve disease, as defined by the US Food and Drug Administration, was found in 6.6% and 1.3% of their subjects, respectively. No patients had symptomatic disease. Unlike some previous studies, which found that the longer patients took phen-fen the more likely they were to have valve disease, the Boston researchers found no association between length of exposure to the drugs and valve disease.

The rate of heart valve disease was similar to a comparable group of patients who had been studied previously in the Framingham Heart Study and who had never taken phen-fen. Dr. Burger and his colleagues observed that a significant portion of healthy people may have abnormal echocardiograms without clinical disease, whether or not they took phen-fen.

In a related editorial by Dr. Nelson B. Schiller, of the University of California at San Francisco, he questions the association between phen-fen and valvular heart disease and notes that "as studies have become more scientifically rigorous, the role of phen-fen in valve disease appears to be approaching the vanishing point.

He also addresses the "insidious problem" of the "almost universal misapplication of echocardiography to the evaluation of valvular regurgitation" raised by the phen-fen experience.