(Circulation. 2000;101:2071.)
© 2000 American Heart Association, Inc.
Clinical Investigation and Reports |
From the Division of Cardiology (J.G.J., C.K.L., J.K., T.R.), Duke University Medical Center, Durham, NC, and Wyeth-Ayerst Research (G.D.C., K.D.D.), Philadelphia, Pa.
Correspondence to James G. Jollis, MD, Box 3542, Duke University Medical Center, Durham, NC 27710. E-mail james.jollis{at}duke.edu
| Abstract |
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Methods and ResultsTo evaluate the potential association between the duration of treatment and the prevalence of heart valve abnormalities, we examined 1163 patients who had taken fenfluramine-phentermine and 672 control patients who had not taken the drug combination within 5 years. Mild or greater aortic regurgitation was present in 8.8% of treated patients and 3.6% of control patients (P<0.001). Moderate or greater mitral regurgitation was present in 2.6% of treated patients and 1.5% of control patients (P=0.18). The adjusted odds ratio compared with controls of aortic regurgitation of mild or greater severity increased according to duration of treatment: 90 to 180 days, 1.5 (P=0.23); 181 to 360 days, 2.4 (P=0.002); 361 to 720 days, 4.6 (P<0.001); >720 days, 6.2 (P<0.001).
ConclusionsThis is the largest study to demonstrate a relation between the length of treatment with fenfluramine-phentermine and the prevalence of valvular abnormalities. These findings suggest that valvular abnormalities in patients who took fenfluramine-phentermine primarily involve those who had taken these medications for >6 months and predominantly results in mild aortic regurgitation. The valve regurgitation identified by this study was not accompanied by significant differences in cardiovascular symptoms nor physical findings other than a higher prevalence of heart murmurs.
Key Words: echocardiography regurgitation valves epidemiology
| Introduction |
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| Methods |
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Prescription registry data were used to identify 33 obesity and general
medicine practices with high prescribing rates of fenfluramine and
phentermine. Among 12 263 patients who had been treated at these
practices, 4013 were randomly selected and contacted to be screened for
study participation. During the screening process, subjects were
considered eligible for the study if they were
18 years old and had a
body mass index >27 kg/m2. Exclusion criteria
included a history of cardiac valvular abnormalities before
anorexigen therapy, history of carcinoid tumor, use of a prescription
or over-the-counter anorexigen other than fenfluramine or phentermine
within 5 years, use of fenfluramine-phentermine for <90 days, or use
of serotonergic medications. On the basis of these criteria, 1864
patients were enrolled, of whom 1835 met eligibility criteria and had
an evaluable echocardiogram including 1137 patients treated with
fenfluramine-phentermine for >90 days, and 672 control patients who
had never taken the drug combination. Of the remaining patients who
were contacted but not enrolled, 1317 patients were not interested in
participating, 758 did not meet study inclusion criteria, and 74 did
not show up for scheduled appointments or did not have a reason listed
in the phone log for not participating
Patients enrolled in the study underwent history and physical examination by the enrolling physician at the clinical site. Echocardiograms were performed on all patients according to a standardized imaging protocol established by sonographer training before initiation of the study. Two-dimensional and Doppler images from the standard parasternal, apical, and subcostal views were recorded on videotape with Sonos model 2000 or 2500 echocardiography machines (Hewlett-Packard) with uniform instrument settings. The studies were interpreted by 4 experienced echocardiographers (T.J.R., C.K.L., J.A.K., J.G.J.) who were blinded to the patients drug treatment status. Abnormal examinations were reinterpreted by a second blinded reader. If the two readers disagreed, differences were adjudicated by a consensus reading.
Multivariate logistic regression analyses were
used to examine the association between duration of prior treatment and
FDA criteria valve regurgitation (mild or greater
aortic regurgitation or moderate or greater mitral
regurgitation) according to a prespecified
analysis plan. Variables with a prevalence of >1% and
significant bivariate association with regurgitation
(P<0.05) were added to the models in a stepwise approach,
retaining significant terms (P<0.05). Candidate
variables included duration of treatment, age, sex, body mass
index, hypertension, diabetes, previous myocardial infarction, and
other drug therapies. Kruskal-Wallis tests were used to compare graded
measures of severity. Continuous measures were compared by ANOVA, and
categorical measures were compared by
2 tests.
All tests of significance were 2-sided.
Echocardiography definitions, regression models,
and participating sites are available from the authors in a technical
report (http://www.dcri.duke.edu).
| Results |
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Demographic and clinical characteristics of the study patients are
presented in Table 1
.
Patients treated with fenfluramine-phentermine were younger and more
likely to be white women and to have taken selective
serotonin reuptake inhibitors (SSRI). The
control group had a slightly lower mean body mass index, was more
likely to have hypertension, diabetes, and previous myocardial
infarction, and was more likely to use ACE inhibitors.
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Echocardiography
Echocardiographic image quality was similar
between treated and control patients, with a distribution of <1%
excellent, 20% good, 68% fair, and 12% poor. Three hundred fifty
echocardiograms were blindly read by a second cardiologist, and 116
studies were blindly read by the same cardiologist a second time. The
statistics regarding interobserver and intraobserver agreement for
mild or greater aortic regurgitation were 0.68 and
0.84, respectively, and 0.78 and 0.86 for moderate or greater mitral
regurgitation.
statistics of 0.61 to 0.80 signify
substantial agreement, and
statistics >0.81 signify almost perfect
agreement.7
The distribution of valve regurgitation by grade
and duration of treatment is presented in Table 2
. Using the FDA criteria, mild or
greater aortic regurgitation was present in 8.8%
of treated patients and 3.6% of control patients
(P<0.001). The majority of cases involving aortic
regurgitation among treated patients were mild in
grade, and the prevalence of mild or greater aortic
regurgitation increased according to length of drug
treatment, from 4.5% for patients treated with the drug combination
for 90 to 180 days (P=0.5) to 17% for patients treated for
>720 days (P<0.001). Using FDA criteria, moderate or
greater mitral regurgitation was found in 2.6% of
treated patients and 1.5% of control patients (P=0.2). In a
comparison of all grades of mitral regurgitation, there
was a significantly higher prevalence of mitral
regurgitation among treated patients, mainly accounted
for by higher rates of trace regurgitation among
patients treated for >360 days (P=0.008). Less than 1% of
patients had both mild or greater aortic regurgitation
and moderate or greater mitral regurgitation. The
prevalences of tricuspid and pulmonic regurgitation
were similar among treated and control patients.
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After adjusting for patient characteristics, the odds ratios compared
with controls of mild or greater aortic regurgitation
ranged from 1.5 (P=0.2) for patients treated for 90 to 180
days to 6.2 (P<0.001) for patients treated for >720 days
(Figure
, A). There was no significant difference in the adjusted rate
of moderate or greater mitral regurgitation compared
with control patients (Figure
, B).
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According to the echocardiographic assessment of
leaflet mobility, there was a trend toward higher prevalence of mild
posterior mitral leaflet restriction that increased according to
duration of treatment (prevalence of mild restriction: 90 to 180 days,
4%; 181 to 361 days, 5%; 361 to 720 days, 5%; >720 days, 7%;
control, 4%; P=0.3). There was no difference in
moderate or severe posterior mitral leaflet restriction nor any degree
of anterior mitral leaflet or aortic valve restriction. Additional
echocardiographic measures according to the presence of
regurgitation meeting FDA criteria and treatment are
presented in Table 3
. These
echocardiographic measures including left
ventricular and left atrial dimensions and estimated
pulmonary artery systolic pressure were similar between
patients with FDA criteria regurgitation who were
treated with fenfluramine-phentermine and control patients. Also, these
measures did not vary according to duration of treatment with
fenfluramine-phentermine for the entire cohort of treated patients.
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Symptoms and Physical Findings
Symptoms and physical findings are presented in
Table 4
. Patients treated with
fenfluramine-phentermine were more likely to report dyspnea on exertion
(P=0.03) and less likely to report chest pain
(P=0.03). Other symptoms including dyspnea at rest and
patient-reported lower-extremity edema were not significantly different
between treated patients and control patients. After adjusting for body
mass index, the association between fenfluramine treatment and dyspnea
on exertion was no longer significant (P=0.1). Of the 318
patients for whom pulmonary artery pressures could be estimated
from tricuspid regurgitation velocity, 20% of patients
with dyspnea on exertion and 15% of patients those without had
pulmonary artery pressures of
40 mm Hg
(P=0.4).
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Among the subgroup of treated patients with FDA criteria
regurgitation, the prevalences of symptoms were similar
to those of control patients (Table 3
). Physical findings
including murmurs, rales, and edema were similar among treated and
control patients. For the subgroup of treated patients with FDA
criteria regurgitation, cardiac murmurs were more
prevalent (FDA criteria regurgitation, 17%; control,
7%; P<0.001).
| Discussion |
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Previous Work
Differences between the findings of this study and previous work
can be accounted for by differences in duration of treatment. Weissman
and colleagues6 examined 718 patients treated with
dexfenfluramine for a relatively short period of time of 72 days mean
duration. The prevalences of aortic and mitral
regurgitation in the Weissman study were similar to
those in our study among patients treated for the shortest period of
time, 90 to 180 days. Among treated patients, the prevalence of mild or
greater aortic regurgitation in the Weissman study was
5.4% compared with 4.5% for the 90- to 180-day cohort in our study.
For mitral regurgitation of moderate or greater
severity, the corresponding prevalence rates from the Weissman study
and our study were 1.8% and 2.2%, respectively. The rates of aortic
and mitral regurgitation among control patients in this
previous study were also similar to our study: 3.6% and 1.2%,
respectively. A study by Khan and colleagues5 of
subjects treated with fenfluramine-phentermine for a mean duration of
805 days found a 25% prevalence of valve regurgitation
meeting the case definition, primarily aortic
regurgitation. The 86 patients treated for >720 days
(mean 913 days) in our study had a 19% prevalence of valve
regurgitation meeting the case definition. Thus,
comparisons of our findings to previous work further support a relation
between duration of therapy and prevalence of
regurgitation, with a relatively low prevalence for
short-term therapy and a significantly higher prevalence for longer
term therapy.
We identified 11 cases of severe aortic or mitral regurgitation among 1163 treated patients. Using the General Practice Research Database from the United Kingdom Department of Health, Jick et al4 identified 11 cases of clinically evident valve regurgitation among 8903 patients treated with dexfenfluramine or fenfluramine. Both findings suggest a relatively low prevalence of severe valve regurgitation. In the study by Connolly et al,2 an initial 24-patient case series included 8 patients with severe regurgitation, 5 of whom underwent valve surgery. The prevalence of regurgitation could not be estimated because the underlying number of patients from whom these cases were identified was indeterminate. To recognize a previously undescribed condition, a predominance of severe regurgitation would be expected in the initial report.
Clinical Significance
The clinical significance of valvular
regurgitation in fenfluramine-phenterminetreated
patients is not completely apparent. From a symptom standpoint, treated
patients with valve regurgitation meeting FDA criteria
had a similar prevalence of symptoms compared with control patients
(Table 3
). However, the overall cohort of treated patients was
increasingly more likely to report dyspnea on exertion according to
longer duration of fenfluramine-phentermine therapy (Table 4
,
P=0.03). The lack of concordance between
echocardiographic findings and reported symptoms can be
attributed to at least 3 explanations. First, drug-associated dyspnea
may be caused by a mechanism independent of valve
regurgitation. Second, recall bias introduced by the
publicity surrounding the withdrawal of fenfluramine may have led
patients with longer drug treatment to be more likely to report
symptoms, resulting in an association that did not correspond with
echocardiographic findings. Third, the findings
regarding dyspnea may have been due to confounding between body mass
index and drug treatment. Patients treated with
fenfluramine-phentermine had greater body mass (Table 1
,
P=0.008), and higher body mass was strongly associated with
symptoms of dyspnea on exertion regardless of therapy (the prevalence
of dyspnea on exertion increased from 12% for patients in the lowest
body mass index tertile to 38% among the highest body mass index
tertile, P<0.001). Thus, it is possible that the higher
prevalence of dyspnea on exertion in treated patients was due to
greater weight rather than drug therapy. After accounting for body mass
index, the relation between drug therapy and dyspnea on exertion was no
longer significant (P=0.1).
Another consideration regarding the significance of valve
regurgitation involves measures of cardiac physiology.
Both chronic aortic and mitral regurgitation lead to
chamber enlargement.8 9 For patients with severe
regurgitation, left ventricular enlargement
is used as one indicator for timing of valve surgery, with surgery
being recommended for end-systolic internal diameters >4.5 cm
for mitral regurgitation and >5.5 cm for aortic
regurgitation. Left ventricular and left
atrial diameters in this study were similar between patients with
regurgitation meeting FDA criteria and control patients
(Table 3
). Although the natural history of valve
regurgitation among patients treated with
fenfluramine-phentermine has yet to be described, these measures
indicate that the majority of regurgitation identified
by this study were not of sufficient severity or duration to affect
chamber size.
Other Drug Interactions
Patients treated with fenfluramine-phentermine were more likely
than control patients to have been treated with an SSRI (24% vs 17%,
P<0.001). On the basis of the hypothesis that fenfluramine
preparations cause valve regurgitation through
alterations in serotonin metabolism, concerns
have been raised about the possibility that SSRIs are also related to
regurgitation, and it is conceivable that the higher
rate of SSRI treatment among fenfluramine-phenterminetreated patients
led to our findings.2 10 11 12 In this study, the
prevalence of aortic and/or mitral regurgitation
meeting FDA criteria among SSRI-treated patients (including treated and
control patients) was actually lower (SSRI 6.7%, no SSRI 8.8%,
P=0.4), particularly among patients who were also
treated with fenfluramine-phentermine (SSRI 7.3%, no SSRI 11.2%,
P=0.09). The trend toward a lower prevalence of
regurgitation among patients treated with both
fenfluramine-phentermine and an SSRI suggests that the latter agents
did not contribute to the valve regurgitation
identified by this study.
Study Limitations
This study had some limitations that should be noted. The
first limitation involves the control group. Because fenfluramine has
been withdrawn from use, a randomized trial could not be conducted.
Therefore, we selected a control group from obese patients treated at
the same clinics who had not taken the study drug. Although this
sampling strategy resulted in cohorts with fairly similar
characteristics, there were some differences between control and
treated patients that may have led to an underestimation of the
difference in valvular regurgitation prevalence
between cohorts. Control patients were on average 1 year older, had a 1
point lower body mass index, and were more likely to have hypertension
and previous myocardial infarction, conditions that could contribute to
an increased prevalence of aortic and mitral
regurgitation and an underestimation of the difference
between groups. Given the similar prevalence of aortic and mitral
regurgitation among control patients in this study and
other studies, a substantial underestimation of the association seems
less likely.5 6 Because all of the baseline differences
noted above would potentially increase the prevalence of
regurgitation among control patients, the possibility
of an overestimation of the effect is even less likely. To account for
differences in clinical characteristics between the control and
treatment cohorts, we used regression analyses that included
terms for these conditions, and the resulting adjusted estimates
represented more balanced comparisons of drug associated
regurgitation.
A second limitation of our study involves the lack of baseline echocardiograms before drug treatment. Without such studies, we cannot be certain which valve regurgitation developed after drug treatment.
Conclusions
We examined 1167 patients who had taken fenfluramine-phentermine
and identified an increased prevalence of valve
regurgitation, mainly involving mild aortic
regurgitation. This is the largest study to demonstrate
a relation between the length of treatment with
fenfluramine-phentermine and valvular abnormalities. Our study
suggests that aortic regurgitation according to the FDA
criteria chiefly occurs among patients treated for >6 months,
increasing in prevalence from 3.6% among control patients and 4.5%
among patients treated for 90 to 180 days (P=0.5) to 17.4%
for patients treated >720 days (P<0.001). The valve
regurgitation identified by this study was not
accompanied by significant differences in
cardiovascular symptoms nor physical findings other
than a higher prevalence of heart murmurs.
| Acknowledgments |
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Received September 21, 1999; revision received December 2, 1999; accepted December 2, 1999.
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