Fenfluramine and dexfenfluramine were voluntarily withdrawn from the
market in September 1997 because of reports of an association with heart valve
abnormalities. Studies have been limited by lack of comparison with untreated
To evaluate cardiovascular status and the prevalence of valvular abnormalities,
as assessed by clinical cardiovascular parameters and echocardiography, in
patients treated for obesity with dexfenfluramine or phentermine/fenfluramine.
Reader-blinded controlled study completed in February 1998.
Setting and Participants
Twenty-five clinical centers in the United States. Of 1640 enrolled
subjects, 1473 were eligible (479 and 455 had taken dexfenfluramine and phentermine/fenfluramine,
respectively, continuously for 30 days or more in the previous 14 months,
and 539 were untreated matched controls) and provided clinical and echocardiographic
data. Mean (SD) age was 47.4 (11.4) years, mean body mass index was 35.0 (7.4)
kg/m2, and 74% were women. Mean (SD) duration of therapy was 6.0
(3.3) months (range, 1-18.4 months) in the dexfenfluramine group, and 11.9
(10.4) months (range, 1.4-63 months) in the phentermine/fenfluramine group,
while the untreated group had no anorexigen use during the previous 5 years.
Main Outcome Measures
Cardiovascular signs and symptoms; echocardiographic evidence of aortic
(AR) or mitral (MR) regurgitation according to US Food and Drug Administration
(FDA) criteria (AR ≥mild or MR ≥moderate) and by grade; tricuspid and
pulmonic valve regurgitation; and aortic, mitral, and tricuspid valve leaflet
mobility and thickness, for treated vs untreated subjects.
Cardiovascular signs and symptoms were similar among anorexigen-treated
and untreated subjects. Prevalence rates and relative risk (RR) of AR were
significantly increased in anorexigen-treated patients and were 8.9% in the
dexfenfluramine group (RR, 2.18; 95% confidence interval [CI], 1.32-3.59),
13.7% in the phentermine/fenfluramine group (RR, 3.34; 95% CI, 2.09-5.35),
and 4.1% in the untreated group (P<.001). No statistically
significant differences in prevalence were observed for MR, thickening or
decreased mobility of any valve leaflet, calculated pulmonary artery systolic
pressure, or left ventricular ejection fraction. Serious cardiac events (including
myocardial infarction, congestive heart failure, or ventricular arrhythmia)
occurring at any time were not statistically different in treated and untreated
subjects (dexfenfluramine, 9.0%; phentermine/fenfluramine, 4.0%; and untreated,
8.4%); and following anorexigen treatment were uncommon (dexfenfluramine,
2.3%; phentermine/fenfluramine, 2.4%, and untreated, 3.3%, when adjusted for
the median start date of anorexigen use).
Our data indicate that use of dexfenfluramine and phentermine/fenfluramine
is associated with an increase in the prevalence of AR using FDA echocardiographic
criteria, but was not associated with an increase in the prevalence of MR
using FDA criteria or with serious cardiac events.