Gersony, Welton M

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EDITORIAL COMMENT
Natural History of Discrete
Subvalvar Aortic Stenosis:
Management Implications*
Welton M. Gersony, MD
New York, New York
Discrete subvalvar aortic stenosis (DSVAS) represents a
unique cardiac lesion. As compared to most other congen-
ital heart defects, DSVAS is virtually never recognized in
early infancy, but appears to be an “acquired” lesion, albeit
with anatomic precursors (1–4). The stenosis is caused by a
fibrous ridge in the left ventricular (LV) outflow tract just
proximal to the aortic valve. An abnormal angle between the
muscular and conal ventricular septum appears to be an
important causative factor, but a definitive etiology has not
been established (5–7). Some investigators have considered
the disease to be a form of cardiomyopathy (8), and there are
patients with DSVAS who develop an unusually profound
LV myocardial hypertrophic response. However, more often
there does not appear to be a global cardiomyopathic
component. In the vast majority of cases, LV hypertrophy
regresses after relief of outflow obstruction, as would be
expected in a patient with valvar aortic stenosis.
See page 835
This condition occurs in patients with associated congen-
ital heart disease, including ventricular septal defect, coarc-
tation of the aorta, interrupted aortic arch, atrioventricular
canal and others (2,9). The lesion may develop in unoper-
ated patients with these defects, but also may appear and
progress significantly after surgical correction of the associ-
ated defect. In addition, DSVAS presents as a primary
defect.
Surgical management of DSVAS consists of removal of
the circumferential fibrous obstructive ridge with or without
septal myectomy. Early reports described complications of
heart block and mitral valve injury as well as incomplete
relief and/or recurrence of obstruction with reoperation
rates of 20% or more (9–12). In recent years, circumferential
enucleation of the fibrous ridge by blunt dissection (13),
occasionally with septal myectomy, appears to provide the
most efficient relief of obstruction. Nevertheless, recurrence
still remains a significant problem, especially in the presence
of a predisposing associated congenital heart defect.
Most reports concerning DSVAS relate to the disease in
infants and children. In the 1970s it was documented by a
number of investigators that, once established, DSVAS
progressed rapidly to severe LV outflow obstruction, with all
of its hemodynamic consequences (14–17). These early
cases defined management, which at most centers was to
intervene surgically when gradients were 30 mm or more
regardless of other aspects of the clinical and echocardio-
graphic profile. Indications for DSVAS surgery became
more aggressive than for valvar aortic stenosis, which is less
likely to progress rapidly in children prior to puberty.
However, it is important to be aware that in the pre-
echocardiographic era, “mild” or “moderate” obstruction
based on direct pressure measurements at cardiac catheter-
ization often reflected rather significant obstruction. The
average preoperative gradient was far higher than is usually
reported in the modern era, when echocardiography iden-
tifies DSVAS at a much earlier stage.
The present-day management policy at most centers
continues to require a significant LV-aortic gradient before
surgery is recommended. However, operative indications
have been expanded by some groups (10,18–20). Rapid
surgical intervention is advocated in infants and children
when a subaortic ridge is shown on echocardiographic study
even when there is no significant predicted gradient. This
rationale is based on the “inevitability” of rapid progression
as well as concerns about eventual aortic valve injury and
dysfunction secondary to unrelieved DSVAS, even in its
mildest form. More recently, however, it has been demon-
strated in children that the rate of progression of mild
DSVAS is variable, and many patients remain stable for
years (2,21). Prevention of aortic valve injury is also ad-
vanced as an indication for early surgery. This has been
controversial as many cardiologists have observed more
aortic insufficiency after DSVAS surgery than before. Cen-
ters that require at least a 30-mm gradient before advocating
surgical intervention consider left ventricular outflow ob-
struction to be the key factor. Among patients with trivial or
mild stenosis, progression of obstruction must be demon-
strated before surgery is recommended.
Although considerations regarding surgical management
and timing of surgical interventions are predicated on
potential long-term effects, there has been little in the
medical literature regarding the disease in adult patients
(22–25), and early reports included small numbers of
patients. In this issue of the Journal, Oliver et al. (26)
present the most extensive data to date on the long-term
aspects of DSVAS in adults and, thus, provide insights into
some of the management issues and controversies. These
investigators describe 134 adults with discrete subvalvar
aortic stenosis, including 29 patients who were operated on
in adult life, 41 operated on during childhood and 64 who
had not had surgery. In the latter group of unoperated
patients, LV outflow tract obstruction increased from
*Editorials published in the Journal of the American College of Cardiology reflect the
views of the authors and do not necessarily represent the views of JACC or the
American College of Cardiology.
From the College of Physicians and Surgeons, Columbia University, New York,
New York.
Journal of the American College of Cardiology Vol. 38, No. 3, 2001
© 2001 by the American College of Cardiology ISSN 0735-1097/01/$20.00
Published by Elsevier Science Inc. PII S0735-1097(01)01454-1
39.2 6 28 mm Hg to 46.8 6 34 mm Hg after a mean
follow-up period of 4.8 6 1.8 years in 25 patients. The
investigators noted that in patients older than 50 years of
age, severity increased significantly, but in young and
middle-aged adults, there was no significant change during
the follow-up period. It also can be noted from their data
that the older patients had more severe gradients at the
initial echocardiogram. In the overall group, 4 of 8 patients
with gradients .50 mm Hg significantly increased the
severity of obstruction, whereas only 3 of 18 patients with
initial gradients under 50 mm Hg showed significant, albeit
mild, progression of the subaortic gradients (19, 33 and 19
mm Hg, respectively). Those with gradients over
50 mm Hg would normally be expected to have surgical
relief of obstruction at the time of the initial echocardio-
gram. Echocardiographic aortic regurgitation was noted in
all patients who had had surgical intervention and in 75% of
unoperated patients. Although not severe, the degree of
regurgitation was significantly greater in the operated pa-
tients.
The conclusions from this study can be summarized as
follows:
c Mild DSVAS most often remains stable or progresses
slowly in adults.
c Aortic regurgitation is common, but is rarely hemody-
namically significant.
c Aortic regurgitation is more prominent in patients after
surgical intervention than in unoperated patients.
Although much remains to be learned about DSVAS, a
number of management principles emerge from both the
Oliver et al. (26) unique large experience in adults and the
more recent pediatric reports. The major issue in determin-
ing whether surgery should be carried out is the severity of
the LV outflow tract obstruction and the age of the patient.
The disease is often rapidly progressive in infancy and early
childhood, but it can also be stable for years; some patients
reaching adult life with only mild obstruction. Aortic
regurgitation associated with DSVAS is usually mild and is
rarely progressive either in unoperated or postsurgical pa-
tients. It appears that adult patients who have had surgical
repair of discrete LV outflow tract obstruction are more
likely to have significant aortic regurgitation than unoper-
ated patients with mild gradients.
At the present time, a reasonable approach to manage-
ment of DSVAS might include the following guidelines:
1. Any patient with DSVAS who has severe obstruction
requires surgical intervention.
2. An infant or young child with a well-defined 30-mm or
more gradient should have removal of the subvalvar
obstruction. Pediatric patients with ,30-mm gradient
and no significant LV hypertrophy must be followed
closely for progression, especially in the first several years
of life.
3. Older children with mild gradients (,30 mm) may be
followed until there is documented significant echocar-
diographic or catheterization progression of the obstruc-
tion, usually with supportive clinical and echocardio-
graphic findings. The inexactness of predictions of
gradient by color Doppler must always be considered in
the decision-making process.
4. Unoperated adult patients with stable predicted gradi-
ents ,50 mm without significant LV hypertrophy must
also be followed closely, as some of these patients will
eventually require surgery.
5. “Prevention” of aortic regurgitation is not a criteria for
surgery in a patient with DSVAS in whom obstruction is
insignificant.
Reprint requests and correspondence: Dr. Welton M. Gersony,
Children’s Hospital of New York, 3959 Broadway 2–North, New
York, New York 10032. E-mail: ds200@columbia.edu.
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845JACC Vol. 38, No. 3, 2001 Gersony
September 2001:843–5 Editorial Comment


Natural history of discrete subvalvar aortic stenosis: management implications∗∗Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology. 

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Natural history of discrete subvalvar aortic stenosis: management implications∗∗Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology.

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