ROCHESTER, MINN. -- New Mayo Clinic research shows that people with mild heart valve disease who took the diet drugs fenfluramine and phentermine may improve after they stop taking the drugs. The report is published in the December issue of Mayo Clinic Proceedings.
"These new findings should be reassuring for those Americans who took fen-phen," says primary author Donald Hensrud, M.D., a Mayo Clinic physician nutrition specialist. "For the first time, we have evidence that heart valve damage -- at least in people with mild disease -- may not be permanent."
In July of 1997, Mayo Clinic and MeritCare, a clinic based in Fargo, N.D., first reported a clinical observation of unusual heart valve disease in 24 patients who had taken fen-phen. Reports of other cases soon followed. Data provided to the FDA showed that up to 30 percent of diet-drug users may have heart valve abnormalities even though they have no symptoms. Based on this information, the makers of fenfluramine and dexfenfluramine voluntarily withdrew the drugs from the market on Sept. 15, 1997. Subsequent studies reported smaller and widely varying prevalence estimates of primarily mild valvular heart disease.
The heart's valves normally allow blood to pass in only one direction. Diseased valves may fail to close completely, causing blood to leak backwards. This makes the heart work harder to pump blood throughout the body and can lead to fatigue, excess fluid accumulation and breathlessness. Severe valve disease may require drug therapy or valve surgery.
The new study examined 30 men and women who were participating in a randomized trial of fen-phen when the drugs were withdrawn from the market. This trial was terminated, and volunteers -- who had taken either fen-phen or placebo for an average of 41 weeks -- were asked to participate in a new study to evaluate potential valve disease associated with the diet drugs.
Most study participants underwent echocardiograhy, a test that uses ultrasound to "look" at the heart, within six weeks after they stopped taking the drugs. Some patients also received echocardiograms six months later to study what happened over time.
Three Mayo Clinic cardiologists -- knowing neither the sequence of the echocardiograms nor which patients in the study took fen-phen versus placebo -- reviewed each patient's baseline and follow-up echo side-by-side. Physician reviewers then judged if valve disease was present and if one of the echos clearly showed less evidence of the disease.
"There was excellent agreement among the three reviewers in identifying drug-related valve disease," says Dr. Hensrud. "Our study found that 26 percent of the original group taking fen-phen had mild aortic valve disease. In addition, we found that heart valve disease did not get worse after patients stopped taking the medications. In fact, it appeared to improve."
"This finding -- that the valve damage may not be permanent -- is good news for patients," Dr. Hensrud continues. "However, we strongly recommend that any patient exposed to fenfluramine or dexfenfluramine receive a complete physical exam by their local physician and an echocardiogram, if there are signs or symptoms of cardiovascular disease or if the physical examination is inconclusive."
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