BONOW
ET AL., ACC/AHA TASK FORCE REPORT
JACC Vol. 32, No. 5, November 1998:1486-1588
ACC/AHA
Guidelines for the Management of Patients With Valvular
Heart Disease
VIII.
Evaluation and Treatment of Coronary Artery Disease
in Patients With Valvular Heart Disease
Many
patients with valvular heart disease have concomitant
CAD, but there are only limited data regarding the optimal
strategies for diagnosis and treatment of CAD in such
patients. Thus, management decisions are usually developed
by blending information from the randomized studies
of treatment of CAD and the smaller published series
of patients undergoing surgical treatment of valvular
heart disease.
A.
Probability of Coronary Artery Disease in Patients With
Valvular Heart Disease
The
probability of developing CAD in the general population
(675) and the prevalence
of CAD in patients coming to medical attention (676)
can be estimated on the basis of age, sex, and clinical
risk factors. The prevalence of CAD in patients with
valvular heart disease is determined by these same variables
(677). Risk factors
for coronary atherosclerosis in patients with valvular
disease should be approached with the prevention and
risk reduction strategies that have been recommended
for the general population (678).
Ischemic
symptoms are important markers of CAD in the general
population. Thus, the prevalence of CAD in middle-aged
men with typical angina has been estimated at ~90%,
in those with atypical angina at ~50%, in those with
nonanginal chest pain at ~16%, and in asymptomatic subjects
at ~4% (676). In contrast,
ischemic symptoms in patients with valvular heart disease
may have multiple causes such as LV chamber enlargement,
increased wall stress or wall thickening with subendocardial
ischemia (376,679),
and right ventricular hypertrophy (680).
Angina is thus a less specific indicator of CAD in patients
with valvular heart disease than in the general population.
Among
patients with severe AS, angina is a common symptom
in young patients with normal coronary arteries and
congenital or rheumatic AS. On the other hand, CAD is
a common finding in older symptomatic men with AS. Among
patients with AS, the prevalence of CAD is 40% to 50%
in those with typical angina, ~25% in those with atypical
chest pain, and ~20% in those without chest pain (681-688).
Even in patients <40 years old with no chest pain
and no coronary risk factors, the prevalence of CAD
is 3% to 5% (677,688,689).
In general, because angina is a poor marker of CAD in
patients with AS, coronary arteriography is recommended
in symptomatic patients before AVR, especially in men
>35 years old, premenopausal women >35 years old
with coronary risk factors, and postmenopausal women.
CAD
is less prevalent in patients with AR than in those
with AS (681-688,690-697),
which is related in part to the younger age of patients
with AR. The prevalence of CAD in patients with MS (~20%)
is lower than in patients with aortic valve disease
(690,692,697-699),
an observation explained principally on the basis of
differences in age and gender. Nonetheless, because
of the impact of untreated CAD on perioperative and
long-term postoperative survival, preoperative identification
of CAD is of great importance in patients with AR or
MS as well as those with AS. Thus, in symptomatic patients
and/or those with LV dysfunction, preoperative coronary
angiography is recommended in men >35, premenopausal
women >35 with coronary risk factors, and postmenopausal
women.
The
relation between MR and CAD is unique in that CAD is
frequently the cause of this valve lesion. The management
of these patients is discussed in section
III.E.5. of these guidelines. Neither angina nor
heart failure symptoms are reliable markers of CAD in
these patients. In patients undergoing catheterization
to evaluate etiology and severity of MR, CAD is present
in ~33% (700,701).
In patients undergoing catheterization for acute ischemic
syndromes, ~20% have associated MR (702).
Those with chronic CAD and MR usually have lower LV
ejection fractions and more extensive CAD than those
without MR (700,703).
B.
Diagnosis of Coronary Artery Disease
The
resting ECG in patients with valvular heart disease
frequently shows ST-segment changes due to LV hypertrophy,
LV dilatation, or bundle branch block, which reduce
the accuracy of the ECG at rest and during exercise
for the diagnosis of concomitant CAD.
Similarly,
resting or exercise-induced regional wall motion abnormalities
are nonspecific markers for CAD in patients with underlying
valvular heart disease who have LV hypertrophy and/or
chamber dilatation (704-706),
as are myocardial perfusion abnormalities induced by
exercise or pharmacological stress (707-711).
Thus, there are few indications for myocardial perfusion
imaging with thallium 201 or technetium 99m perfusion
agents in patients with severe valvular disease, and
coronary arteriography remains the most appropriate
method for the definitive diagnosis of CAD (1).
Noninvasive imaging is useful when CAD is suspected
in patients with mild valve stenosis or regurgitation
and normal LV cavity size and wall thickness.
Recommendations
for Coronary Angiography in Patients With Valvular Heart
Disease
C.
Treatment of Coronary Artery Disease at the Time of
Aortic Valve Replacement
As
noted previously, >33% of patients with AS
undergoing AVR have concomitant CAD. More than 50% of
patients >70 years old have CAD. Several studies
have reported the outcomes of patients undergoing combined
coronary artery bypass surgery and AVR. Although combined
myocardial revascularization and AVR increases cross
clamp time (712) and
has the potential to increase perioperative myocardial
infarction and early postoperative mortality in comparison
with patients without CAD undergoing isolated AVR (713-716),
in several series combined coronary artery bypass surgery
has had little or no adverse effect on operative mortality
(717-724).
Moreover, combined coronary bypass grafting and AVR
reduces the rates of perioperative myocardial infarction,
operative mortality, and late mortality and morbidity
compared with patients with significant CAD who did
not undergo revascularization at the time of AVR (723-726).
In addition to severity of CAD, the multivariate factors
for late postoperative mortality include severity of
AS, severity of LV dysfunction, age >70 (especially
in women), and presence of NYHA functional Class IV
symptoms (724,727,728).
Incomplete revascularization is associated with greater
postoperative systolic dysfunction (729,730)
and reduced survival rates (731)
after surgery compared with patients who receive complete
revascularization. For over a decade, improved myocardial
preservation techniques have been associated with reduced
overall operative mortality (732),
and it has become standard practice to bypass all significant
coronary artery stenoses when possible in patients undergoing
AVR. The committee recommends this approach.
D.
Aortic Valve Replacement in Patients Undergoing Coronary
Artery Bypass Surgery
Patients
undergoing coronary artery bypass surgery who have severe
AS should undergo AVR at the time of revascularization.
Decision making is less clear in patients who have CAD
requiring coronary bypass surgery who have mild to moderate
AS. Controversy persists regarding the indications for
"prophylactic" AVR at the time of coronary
bypass surgery in such patients. This decision should
be made only after the severity of AS is determined
carefully by Doppler echocardiography and cardiac catheterization.
Confirmation
by cardiac catheterization is especially important in
patients with reduced stroke volumes, mixed valve lesions,
or intermediate mean aortic valve gradients (between
30 and 50 mm Hg) by Doppler echocardiography, as many
such patients may actually have severe AS (as discussed
in detail in section III.A.
of these guidelines). The more complex and controversial
issue is the decision to replace the aortic valve for
only mild AS at the time of coronary bypass surgery
because the degree of AS may become more severe within
a few years, necessitating a second, more difficult
AVR operation in a patient with patent bypass grafts.
It
is difficult to predict whether a given patient with
CAD and mild AS is likely to develop significant AS
in the years after revascularization surgery. As noted
previously (section III.A.3. of these guidelines), the
natural history of mild AS is variable, with some patients
manifesting a relatively rapid progression of AS with
a decrease in valve area of up to 0.3 cm2
per year and an increase in pressure gradient of up
to 15 to 19 mm Hg per year; however, the majority may
show little or no change (72-84).
The average rate of reduction in valve area is ~0.12
cm2 per year (84),
but the rate of change in an individual patient is difficult
to predict.
Retrospective
studies of patients who have come to AVR after previous
coronary bypass surgery have been reported in whom the
mean time to reoperation was 5 to 8 years (733-737).
The aortic valve gradient at the primary operation was
small, <20 mm Hg, but the mean gradient increased
significantly to >50 mm Hg at the time of the second
operation. It is important to note that these represent
selected patients in whom AS progressed to the point
that AVR was warranted. The number of patients in these
surgical series who had similar gradients at the time
of the primary operation but who did not have significant
progression of AS is unknown.
Although
definitive data are not yet available, patients with
intermediate aortic valve gradients (30 to 50 mm Hg
mean gradient at catheterization or 3 to 4 m/s transvalvular
velocity by Doppler echocardiography) who are undergoing
coronary artery bypass surgery may warrant AVR at the
time of revascularization, but this is controversial
because there are limited data to indicate the wisdom
of this general policy. In most patients with normal
stroke volumes and small mean gradients (<30 mm Hg
and/or <3 m/s), there is greater controversy regarding
AVR at the time of coronary artery bypass surgery, and
the strength of this recommendation is reduced.
Recommendations
for Aortic Valve Replacement in Patients Undergoing
Coronary Artery Bypass Surgery
E.
Management of Concomitant Mitral Valve Disease and Coronary
Artery Disease
Most
patients with both mitral valvular disease and CAD have
ischemic MR, as discussed in section
III.E.5. of these guidelines. In patients with 1
to 2+ MR, ischemic symptoms usually dictate the need
for revascularization, and the mitral valve is rarely
repaired or replaced unless intraoperative echocardiography
indicates more severe MR. In patients with more severe
MR, the mitral valve is addressed surgically, and all
obstructed coronary arteries are revascularized.
In
patients with mitral valve disease due to diseases other
than ischemia, significantly obstructed coronary arteries
identified at preoperative cardiac catheterization are
generally revascularized at the time of mitral valve
surgery. There are no data to indicate the wisdom of
this general policy, but because revascularization usually
adds little morbidity or mortality to operation, the
additional revascularization surgery is usually recommended.
©
1998 American College of Cardiology and American Heart
Association, Inc. Published by Elsevier
Science Inc.
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