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PROCEEDINGS
OF THE 32ND BETHESDA CONFERENCE
CARE OF THE ADULT WITH CONGENITAL HEART DISEASE
JACC Vol. 37, 2001: 1161-98
32nd
Bethesda Conference:
Care of the Adult With Congenital Heart Disease
Carole A. Warnes, MD, FACC, Co-Chair, Richard Liberthson,
MD, Co-Chair, Gordon K. Danielson, Jr, MD, Annie Dore,
MD, FRCP, Louise Harris, MD, ChB, FACC, Julien I.E.
Hoffman, MD, FACC, Jane Somerville, MD, FACC, Roberta
G. Williams, MD, FACC, Gary D. Webb, MD, FACC
Task
Force 1: The Changing Profile of Congenital Heart Disease
in Adult Life
The
extraordinary advances in cardiac surgery, intensive
care, and noninvasive diagnosis over the last 50 years
have led to an enormous growth in the U.S. and throughout
the world in the number of adults with congenital heart
disease (CHD). Approximately 85% of babies born with
cardiovascular anomalies can expect to reach adulthood,
and with continued improvement in surgical technique,
this could increase further in the next two decades(1).
In Canada, it is estimated that the number of survivors
with adult congenital heart disease (ACHD) will increase
from 94,000 in 1996 to 124,000 by the end of 2006. Although
there is a general recognition that there are large
numbers of adults with CHD in the U.S., accurate statistics
are lacking. Reported prevalence rates of CHD in newborns
vary widely and depend, to some extent, on lesion inclusion
and exclusion criteria. For example, some studies include
ventricular septal defects (VSDs); however, about two
thirds of these individuals no longer have a VSD by
adult age. Many studies exclude bicuspid aortic valves,
which are present in 1% of live births. In addition,
different methods of ascertainment (e.g., physical examination,
echocardiography, registry data) yield varying prevalence
rates of CHD in infancy.
A
recent English study(2)
reviewed all births in one health region (Newcastle)
between 1985 and 1994, and noted 1,942 cases of CHD
in a population of 377,310 live births (incidence of
5.2 per 1,000). Of these newborns, 1,514 were predicted
to survive ≥16 years. Because additional diagnoses
are sometimes made later in childhood, at least 2,192
children were expected to survive ≥16 years. Also,
an estimated 784 would require follow-up in adult life.
These figures predict the need for follow-up of adults
with CHD, for >200 cases per 100,000 live births, or
>1,600 cases every year in the U.K. (assuming a population
of 50 million). Assuming a population of 280 million
in the U.S., that would mean an increase of 8,960 adult
cases annually, or 89,600 cases in the current decade.
Most
studies from the mid 1980s onward, however, as well
as more recent Canadian studies, report the number of
CHD births to be close to 10 in 1,000 live births(3).
Defining the exact size and composition of this population
in adulthood is challenging, because data are lacking.
An important mandate of this Bethesda Conference is
to estimate patient numbers, which are essential for
program planning and resource allocation. On the basis
of the U.S. census data, the documented birth rates
from 1940 to 1989 were averaged (Table
1, Table 2, Table
3). The diagnoses corresponding to complex, moderate,
and mild lesions are shown in Table
4, Table 5, and Table
6 and are those used by Task Force 4. Based on a
documented incidence of 1.5 in 1,000 live births for
complex CHD (Table 1) and by
extrapolating likely survival rates for the early through
more recent years, the approximate numbers of survivors
in this group were derived. The incidence of 1.5 in
1,000 live births was based on the large New England
Regional Infant Cardiac Program (NERICP) review of catheterization
data, surgical findings, and postmortem diagnoses(4).
Using this approach, ~117,000 adults with truly complex
CHD are estimated to live in the U.S. in the year 2000.
With improved surgical techniques, this number can be
anticipated to increase over the next decade.
Using
a similar model, (Table 2) demonstrates
the anticipated survival, to the year 2000, of patients
with moderate CHD, as defined in Table
5. A prevalence of 2.5 in 1,000 is derived from
published data on children, as well as some patients
who began with more simple lesions but acquired complications
(e.g., VSD with valve lesions, patent ductus arteriosus
causing left heart dilation) (Table
7). These estimates predict an adult population
of 302,000 with moderate CHD by the year 2000 in the
U.S.
Estimating
the number of adult patients with simple CHD (Table
3, Table 6) is more difficult.
To utilize the absolute prevalence of simple lesions
detected in infancy would grossly overestimate the number
of adult survivors, because most VSDs will have closed
by adulthood, and these patients will no longer be considered
to have CHD. Thus, there will be considerable ”attrition”
of the numbers of patients with VSDs between the incidence
at birth and the prevalence in adulthood. Most patients
with a patent ductus arteriosus will undergo surgical
or spontaneous closure in childhood (by definition,
therefore, remaining “simple”), but a small
proportion will remain patent, many needing closure,
and are therefore defined as “moderate” cases.
By utilizing these assumptions (Table
7), the prevalence of these lesions is derived:
~2.2 in 1,000. Thus, the estimated survival of patients
with simple CHD in the U.S. to the year 2000 is 368,800.
A conservative estimate of the total number of survivors—combining
the mild, moderate, and complex subgroups—is
787,800. The addition of those with isolated bicuspid
aortic valves would dramatically increase this number.
The moderate and complex subgroups—totaling 419,000
patients—need periodic (e.g., every 6-24 months)
follow-up in a regional ACHD center.
These
figures may well be underestimates for two important
reasons. First, they are based on the incidence of CHD
presenting in infancy and childhood, but at least
10% of cases seen in an ACHD clinic (in particular,
secundum atrial septal defect, Ebstein's anomaly, and
congenitally corrected transposition) are not diagnosed
until adulthood. In addition, increasing numbers of
immigrants to the U.S. add to the patient population.
Therefore, a conservative estimate of patients needing
periodic follow-up at a regional ACHD center is ~400,000.
Although these predictions, again, are based on several
assumptions, they provide a framework to estimate current
and future resource requirements necessary to provide
optimal care.
This
population growth is also reflected in the growth of
individual regional ACHD centers. In Toronto, a 269%
expansion in the outpatient work load was noted over
a 10-year period between 1987 and 1997. Similarly, an
increase in the number of admissions to a large ACHD
unit in the U.K. is shown in Figure 1. Age range of
patients with CHD at hospital admission in a single
center from 1975 onwards. The unit was opened as an
adolescent unit in 1975 at the National Heart Hospital,
joined by the Royal Brompton Hospital in 1990. Statistics
from Jane Somerville, London, U.K. Notably, these admissions
continue to increase, particularly for patients >30
years of age; by 1996, 30% of patients admitted were
>40 years of age.
Disease
Patterns
Data
on the basic diagnosis and age of outpatients in a large
unit in the U.K. in 1997 are also presented (Figure
2 and Figure 3). Complex lesions,
such as tricuspid atresia and single-ventricle physiology,
are well represented in patients >20 years of age, particularly
in those >30 years of age, in current ACHD centers.
The age range of patients seen in two large clinics
is shown in Figure 4;
they
were older in the Mayo Clinic than in the Toronto series,
where 50% versus 30% of patients were ≥40 years
of age. These more complex patients are obviously vulnerable
to additional acquired co-morbidities that impact both
their cardiac and medical care, including hypertension,
pulmonary, renal, and myocardial disease, and coronary
artery disease. It is estimated that ~55% of the adult
patient population is at medium to high-risk (defined
as those at significant risk for premature death, re-operation,
and complications) and thus need to be seen regularly
in ACHD regional centers and followed for life. These
patients include those with atresia, single-ventricle
physiology, transposition variants, Ebstein's anomaly,
tetralogy of Fallot, pulmonary vascular disease, and
complex septal defects. Periodic review at a regional
ACHD center continues to offer advantages over a general
cardiac evaluation, particularly regarding the timing
and type of intervention, follow-up strategy, and general
recommendations (5).
Approximately 45% of patients with mild defects, such
as a small VSD or mild pulmonary valve stenosis, will
not require regular follow-up in a regional ACHD center,
but might benefit from at least one review at such a
center at the discretion of the patient's physician.
The
profile of this patient population will change over
the next few decades, not only because of advancing
age, but also with improved survival of patients with
complex anomalies. In addition, with the impetus to
perform definitive repair at an earlier age and with
changing operative procedures, there will be changes
in the anticipated disease patterns. Many adult survivors
will have different hemodynamic and cardiac problems
from those currently seen. For example, an infant with
transposition of the great arteries will no longer have
a Mustard or Senning procedure (with its late problems
of systemic ventricular dysfunction and arrhythmias),
but might be anticipated to have an arterial switch
procedure and encounter quite different cardiac sequelae
in adult life. Patients with complex single-ventricle
physiology and various modifications of the Fontan procedure
will increase in number. Perhaps with refinements in
noninvasive diagnosis and earlier definitive repair
of shunt lesions, the prevalence of pulmonary vascular
disease and Eisenmenger syndrome in the adult population
could be expected to diminish. These patients with complex
malformations are subject to more diverse and numerous
late complications and must be seen regularly at a regional
ACHD center, to which they should have direct access.
They need more intensive follow-up and probably more
frequent re-evaluations and interventions.
Special Resources
Impact
of cardiac surgery. In the largest congenital cardiac
center in the U.K., one in five admissions was for cardiac
surgery. The Society of Cardiothoracic Surgeons of the
U.K. Registry for 1998/1999 reports that in the U.K.,
3,836 congenital heart operations were performed, with
a mortality rate of 4.7%. There were 339 patients ≥16
years of age, with a mortality rate of 2.1%, but the
data were not stratified according to low- and high-volume
units, nor were they audited.
Some
centers reported a surprisingly low number of ACHD operations
per year, although expertise is often focused in centers
where the same surgeons operate on both pediatric and
adult patients, so the numbers can be combined. Previously
published data from Stark et al.(6)
have shown that mortality is higher in centers with
lower operative volume, highlighting the risk of performing
the “occasional” operation on adult patients
with CHD.
It
is estimated in the U.S. that 20,000 operations for
CHD are performed every year. Based on pediatric data,
low-volume centers have a higher mortality. The outcome
is likely to be worse for adult patients who do not
always have the benefit of a surgeon with special expertise
and training in CHD. It is important, both medically
and financially, to concentrate resources and funding
and place patients in specialized centers. A close collaboration
is necessary between experienced and trained cardiologists,
echocardiographers, interventional cardiologists, surgeons,
and anesthesiologists, with well-trained nurses on every
team. The expert surgical care provided to children
with cardiac anomalies must also be provided to adults.
Re-operations are frequent, and the overall mortality
is higher in patients having a re-operation versus a
first operation(7).
In one U.S. center (Mayo Clinic) following >1,800 patients,
1,243 of whom had cardiac surgery, almost 50% had two
or more operations and 290 (23%) had three or more operations.
This necessity for re-operation (particularly in patients
with bioprosthetic valves and extracardiac conduits),
again emphasizes the need for special surgical expertise
in CHD. The types of operations in adult patients in
a single center (Mayo Clinic) by diagnosis and age are
shown in Table 8.
Operative
mortality varies according to the basic diagnosis, the
type of surgical repair, and the complexity of the anatomy.
Re-operation poses technical difficulties for the surgeon
because of adhesions (especially between the heart,
aorta or conduit, and sternum), lack of retrosternal
space, loss of anatomic landmarks (especially the coronary
arteries) or the development of collateral vessels.
In addition, there may be deleterious effects of all
previous bypass operations on long-term myocardial function.
Cyanotic patients face a higher mortality and more postoperative
complications. Increasing age is associated with a higher
mortality because additional co-morbid factors (as outlined
previously) increase the operative risk. A detailed
preoperative evaluation performed by an experienced
medical and surgical team is essential. Transthoracic
and transesophageal echocardiography, cardiac catheterization,
and magnetic resonance imaging are necessary complementary
tools to help the physicians make appropriate decisions.
Holter monitoring and electrophysiologic study may determine
if significant arrhythmias are present. Adults often
report that they are asymptomatic as they adapt to their
chronic condition and do not exercise beyond their limits.
Exercise testing, critical evaluation of the patient’s
functional class, and assessment of ventricular function
will help to determine the timing, risk, and success
of the operation.
Transplantation
is sometimes needed when the cardiac anatomy is not
suitable for an operation or when ventricular dysfunction
is too severe. The indications for transplantation are
similar to those in patients with other cardiac conditions,
and should be considered in patients who have New York
Heart Association functional class IV symptoms, despite
optimal medical therapy and in the absence of other
therapeutic options. The number of adults with CHD requiring
heart transplantation is currently relatively small,
and an even smaller group has been reported with heart
and lung transplantation. Transplantation in adults
with CHD has been most frequently performed in patients
with Fontan-type repair, transposition of the great
arteries after a Mustard or Senning procedure with severe
systemic (morphologically right) ventricular dysfunction,
congenitally corrected transposition with ventricular
dysfunction, severe Ebstein's anomaly or Eisenmenger
syndrome. Transplantation needs may also increase in
the next two decades, as more children with complex
single-ventricle physiology undergo Fontan-like repair.
Electrophysiology.
There is a growing recognition that arrhythmias, both
atrial and ventricular, are an increasing problem in
terms of management in these patients, and they are
often associated with increasing morbidity and mortality.
This is a consequence of: 1) underlying anatomic abnormalities;
2) chamber dilation and progressive fibrosis; 3) previous
surgical incisions; and 4) compromised hemodynamic status.
Pharmacologic management options for these patients
may be limited by concomitant sinus node dysfunction,
significant associated systemic ventricular dysfunction,
and the desire for pregnancy.
Over
last few years, newer, nonpharmacologic management options
have emerged, specifically: 1) catheter ablation; 2)
surgical approaches targeting structural abnormalities
as well as offering intraoperative electrophysiologic
ablation; and 3) automatic implantable internal defibrillators
and a new generation of pacemakers with algorithms designed
to prevent and treat atrial tachyarrhythmias. With some
exceptions, in this population catheter ablation has
met with only modest success so far; it is anticipated
that ongoing refinements of mapping and ablation techniques
will result in improved outcomes. A combined surgical
approach has been employed successfully in the management
of atrial arrhythmias, including those in patients with
Ebstein's anomaly and patients undergoing Fontan revision,
including the arrhythmias (both atrial and ventricular)
seen after tetralogy of Fallot repair.
These
approaches, again, emphasize the desirability of a closely
integrated collaboration between the surgeon, electrophysiologist,
and cardiologist. With refinements in medical and nonpharmacologic
therapy, it is anticipated that the need for arrhythmia
therapy will increase in this aging population. The
newer generation of atrial antitachycardia pacemakers
and/or defibrillators will hopefully offer an expanded
range of therapeutic options for these patients. However,
issues of venous access, intracardiac shunts, and thromboembolic
risk will often preclude a transvenous approach for
lead implantation, and an epicardial approach may need
to be considered. Data from current automatic implantable
cardioverter-defibrillator trials in patients with ischemic
or dilated cardiomyopathy appear to support expanded
indications for automatic implantable cardioverter-defibrillator
use in patients with substantial ventricular dysfunction,
nonsustained ventricular tachycardia, and inducible
ventricular tachycardia according to the electrophysiologic
study. It is possible that these results may be extrapolated
to adults with CHD, suggesting that the rate of automatic
cardioverter-defibrillator implantation will continue
to increase in this patient population.
Catheterization/Intervention.
Cardiac catheterization has been the diagnostic “gold”
standard for CHD for the past 50 years. For the past
20 years, it has been increasingly supplemented by noninvasive
diagnostic modalities; initially, cardiac ultrasound
and, more recently, computed tomographic scanning and
magnetic resonance imaging. Advances in these technologies
have been logarithmic, and it is likely that in the
coming decade, both morphologic and functional assessments
of this patient population will be increasingly accomplished
noninvasively.
Today,
diagnostic catheterization is largely reserved for resolution
of specific issues concerning operative interventions,
including: 1) the preoperative evaluation of coronary
arteries; 2) the assessment of pulmonary vascular disease
and its response to vasoactive agents for planned, traditional
surgical intervention and/or heart or heart/lung transplantation;
and 3) as an adjunct to the noninvasive assessment of
the morphologic and functional characteristics of many
complex congenital lesions (e.g., delineation of arterial
and venous anatomy, patients with heterotaxy, Fontan
candidates, and patients who have had previous palliation
in the form of a shunt). Such procedures should be performed
by experienced and trained operators who maintain an
adequate minimal volume annually.
Evaluation
for possible interventional catheterization has become
an increasingly common indication for diagnostic catheterization.
For some lesions, notably valvular pulmonary stenosis,
branch pulmonary stenosis, residual or recurrent aortic
coarctation, and arteriovenous fistulae, catheter intervention
is widely considered to be the treatment of choice.
Coil or device occlusion of the patent ductus produces
results comparable to those of surgical closure, and
device closure of secundum atrial septal defects is
often employed, although the success rate varies with
operator expertise and the specific device used. It
is likely that technical problems related to these devices
will ultimately be overcome. Dilation of stenotic palliative
shunts can obviate the need for re-operation, and transcatheter
occlusion of shunts before repair of intracardiac lesions
may simplify the surgical procedure. Along with the
growth of interventional catheterization, there has
been a renewed interest in small-incision cardiac surgery,
and there will likely be continued advocacy for both
management alternatives. Finally, a national and global
perspective must be kept in mind, relative to limited
resources in developing regions where interventional
catheterization may provide partial or definitive treatment
for many patients with CHD who do not have access to
cardiac surgery.
Echocardiography.
With improvements and refinements in echocardiographic
technology, most adults attending an outpatient clinic
undergo transthoracic echocardiography and, when necessary,
complementary transesophageal echocardiography and magnetic
resonance imaging. Two-dimensional imaging is more challenging
in this patient population because of larger body size
and often multiple previous surgical scars. The use
of transesophageal echocardiography intraoperatively
is also increasing, and it has been shown that it has
a major impact on cardiac surgical procedures in 6%
to 9% of cases (i.e., that it is desirable or necessary
for the patient to resume cardiopulmonary bypass for
revision of the cardiac procedure). Physicians interpreting
these echocardiograms need to be experienced and have
expertise in all aspects of CHD.
A
high rate of diagnostic errors in pediatric echocardiograms
performed in community-based adult laboratories has
been reported(8). This
study reported patients of varying ages, from one day
to 18 years, and either interpretive or technical errors
that were of major or moderate importance occurred in
53% of cases. There is reason to believe that in older
patients, errors occur even more frequently because
image acquisition is more challenging. Clearly, both
expertise and technology are necessary to provide the
best care.
Conclusions.
The data, estimates, and models described herein emphasize
that patients in the U.S. have been underserved by the
present health care system. Over the next decade, a
more comprehensive system must be developed for this
growing population, with considerable collaboration
between cardiologists specializing in pediatrics and
adults. This Conference will facilitate the further
recognition of these needs and hopefully help to develop
the resources needed to achieve these objectives.
© 2001 by The American College of
Cardiology
Published by Elsevier
Science Inc.
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