(Circulation. 1998;98:1949-1984.)
© 1998 American Heart Association, Inc.
ACC/AHA Practice Guidelines |
Guidelines for the Management of Patients With Valvular Heart Disease
Executive SummaryA Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Patients With Valvular Heart Disease)
Key Words: AHA Medical/Scientific Statements • valves • regurgitation • stenosis • mitral valve
I. Introduction
This executive summary and recommendations appears in the November 3, 1998, issue of Circulation. The guidelines in their entirety, including the ACC/AHA Class I, II, and III recommendations, are published in the November 1, 1998, issue of the Journal of the American College of Cardiology. Reprints of both the full text and the executive summary and recommendations are available from both organizations.
During the past 2 decades, major advances have occurred in diagnostic techniques, the understanding of natural history, and interventional cardiological and surgical procedures for patients with valvular heart disease. The information base from which to make clinical management decisions has greatly expanded in recent years, yet in many situations, management issues remain controversial or uncertain. Unlike many other forms of cardiovascular disease, there is a scarcity of large-scale multicenter trials addressing the diagnosis and treatment of valvular disease from which to derive definitive conclusions, and the literature represents primarily the experiences reported by single institutions in relatively small numbers of patients.
The Committee on Management of Patients With Valvular Disease was given the task of reviewing and compiling this information base and making recommendations for diagnostic testing, treatment, and physical activity. These guidelines follow the format established in previous American College of Cardiology/American Heart Association (ACC/AHA) guidelines for classifying indications for diagnostic and therapeutic procedures:
Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective
Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment
IIa. Weight of evidence/opinion is in favor of usefulness/efficacy
IIb. Usefulness/efficacy is less well established by evidence/opinion.
Class III: Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful and in some cases may be harmful.
This task force report overlaps with several previously published ACC/AHA guidelines for cardiac imaging and diagnostic testing, including the Guidelines for Clinical Use of Cardiac Radionuclide Imaging,1 the Guidelines for the Clinical Application of Echocardiography,2 the Guidelines for Exercise Testing,3 and the Guidelines for Coronary Angiography.4 Although these guidelines are not intended to include detailed information covered in previous guidelines on the use of imaging and diagnostic testing, a discussion of the indications for these tests in the evaluation and treatment of patients with valvular heart disease is an essential component of this summary.
The committee emphasizes the fact that many factors ultimately determine the most appropriate treatment of individual patients with valvular heart disease in individual communities. These factors include the availability of diagnostic equipment and expert diagnosticians, the expertise of interventional cardiologists and surgeons, and notably the wishes of well-informed patients. Therefore, deviation from these guidelines may be appropriate in some circumstances. These guidelines are written with the assumption that a diagnostic test can be performed and interpreted with skill levels consistent with previously reported ACC training and competency statements and ACC/AHA guidelines, that interventional cardiological and surgical procedures can be performed by highly trained practitioners within acceptable safety standards, and that the resources necessary to perform these diagnostic procedures and provide this care are readily available. This is not true in all geographic areas, which further underscores the committee's position that these recommendations are guidelines and not rigid requirements.
II. General Principles
A. Evaluation of the Patient With a Cardiac Murmur
A heart murmur may have no pathological significance or may
be an important clue to the presence of valvular, congenital,
or other structural abnormalities of the heart. Most systolic
heart murmurs do not signify cardiac disease, and many are related to
physiological increases in blood flow velocity. In
other instances, a heart murmur may be an important clue to the
diagnosis of undetected cardiac disease that may be important even when
asymptomatic or that may define the reason for cardiac
symptoms. In these situations, various noninvasive or invasive cardiac
tests may be necessary to establish a firm diagnosis and form the basis
for rational treatment of an underlying disorder. Two-dimensional (2-D)
and Doppler echocardiography is particularly
useful in this regard. Diastolic murmurs virtually always
represent pathological conditions and require further cardiac
evaluation, as do most continuous murmurs. Continuous "innocent"
murmurs include venous hums and mammary soufflés.
An important consideration in a patient with a cardiac murmur is the presence or absence of symptoms. Many asymptomatic children and young adults with grade 2/6 midsystolic murmurs and no other cardiac physical findings need no further cardiac workup after the initial history and physical examination. A particularly important group is the large number of asymptomatic elderly patients, many with systemic hypertension, who have midsystolic murmurs related to sclerotic aortic valve leaflets, flow into tortuous, noncompliant great vessels, or a combination of these. Such murmurs must be distinguished from murmurs caused by mild to severe valvular aortic stenosis (AS), which is prevalent in this age group.
Although echocardiography usually provides more specific and often quantitative information about the significance of a heart murmur and may be the only test needed, the electrocardiogram (ECG) and chest x-ray are readily available and may have already been obtained. The absence of ventricular hypertrophy, atrial abnormality, arrhythmias, conduction abnormalities, prior myocardial infarction, and evidence of active ischemia on the ECG provides useful negative information at a relatively low cost. Abnormal findings on the ECG such as ventricular hypertrophy or a prior infarction should lead to a more extensive evaluation, including 2-D and Doppler echocardiography.
Echocardiography
Echocardiography is an important noninvasive
method for assessing the significance of cardiac murmurs. 2-D
echocardiography may indicate abnormal
valvular motion and morphology but usually does not indicate
the severity of valvular stenosis or
regurgitation except in mitral stenosis (MS).
Doppler echocardiography identifies increased
velocity of flow across stenotic valves from which the severity
of stenosis may be determined. The presence of an abnormal
regurgitant jet on Doppler color flow imaging indicates
valvular regurgitation and provides
semiquantitative information about its severity.
Although 2-D echocardiography and color flow Doppler imaging can provide important information on patients with cardiac murmurs, these tests are not necessary for all patients with cardiac murmurs and usually add little but expense in the evaluation of asymptomatic patients with short grade 1 to 2 midsystolic murmurs and otherwise normal physical findings. Alternatively, if the diagnosis is still questionable after transthoracic echocardiography, transesophageal echocardiography or cardiac catheterization may be appropriate. Many recent studies indicate that Doppler ultrasound devices are very sensitive and may detect valvular regurgitation through the tricuspid and pulmonic valves in a large percentage of healthy subjects and through left-sided valves (particularly the mitral) in a variable but lower percentage.
General recommendations for performing 2-D and Doppler
echocardiography in asymptomatic and
symptomatic patients with heart murmurs follow. Of course,
individual exceptions to these indications may exist.
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There are very few data addressing the cost-effectiveness of various approaches to the patient undergoing medical evaluation of a cardiac murmur. Optimal auscultation by well-trained examiners who can recognize an insignificant midsystolic murmur with confidence results in less frequent use of expensive additional testing to define murmurs that do not indicate cardiac pathology.
Many murmurs in asymptomatic adults are innocent and have no functional significance. Such murmurs have the following characteristics: (1) grade 1 to 2 intensity at the left sternal border, (2) a systolic ejection pattern, (3) normal intensity and splitting of the second heart sound, (4) no other abnormal sounds or murmurs, and (5) no evidence of ventricular hypertrophy or dilatation and the absence of increased murmur intensity with the Valsalva maneuver. Such murmurs are especially common in high-output states such as pregnancy.
In the evaluation of heart murmurs, the purposes of echocardiography are to (1) define the primary lesion in terms of etiology and severity, (2) define hemodynamics, (3) define coexisting abnormalities, (4) detect secondary lesions, (5) evaluate cardiac chamber size and function, (6) establish a reference point for future comparisons, and (7) reevaluate the patient after an intervention.
B. Endocarditis and Rheumatic Fever Prophylaxis
1. Endocarditis Prophylaxis
Endocarditis is a serious illness associated with significant
mortality. Its prevention by appropriate administration of antibiotics
before procedures expected to produce bacteremia merits serious
consideration. Several issues must be considered in generating
recommendations for endocarditis prophylaxis. It has been suggested
that the risk of endocarditis in patients with preexisting cardiac
disorders be classified as relatively high risk, moderate risk, and low
or negligible risk, as determined by the cardiac disorder. Guidelines
for the prevention of endocarditis have been issued by the American
Heart Association,5 and the current committee
endorses those guidelines, with the following comments:
This committee recommends prophylaxis in hypertrophic
cardiomyopathy only when there is latent or resting
obstruction.
Patients with mitral valve prolapse (MVP) without
regurgitation require additional clinical judgment.
Indications for antibiotic prophylaxis in MVP are discussed in section
III.D. Patients who do not have mitral regurgitation (MR) but do have
echocardiographic evidence of thickening and/or
redundancy of the valve leaflets and especially men 
45 years may be
at increased risk for bacterial endocarditis.5
Additionally, approximately one third of patients with MVP without MR
at rest may have exercise-induced MR. Some patients may exhibit MR at
rest on 1 occasion and none on others. There are no data available to
address this latter issue, and at present, the decision must be
left to clinical judgment, taking into account the nature of the
invasive procedure, the previous history of endocarditis, and the
presence or absence of valve thickening and/or redundancy.
In patients with echocardiographic evidence
of physiological MR in the absence of a murmur and
with structurally normal valves, prophylaxis is not recommended. The
committee also does not recommend prophylaxis for
physiological tricuspid and pulmonary
regurgitation detected by Doppler in the absence of
a murmur, as such findings occur in a large number of normal
individuals and the risk of endocarditis is extremely low.
Recommendations regarding Doppler
echocardiography for purposes of antibiotic
prophylaxis in patients who have received anorectic drugs are given in
section III.H. of these guidelines.
Various dental and/or surgical procedures are associated with varying degrees and frequencies of bacteremia. Recommendations for endocarditis prophylaxis, as determined by the dental and/or surgical procedure, are provided in full in the AHA recommendations for prevention of bacterial endocarditis5 and the full text of these guidelines.
2. Rheumatic Fever Prophylaxis
Rheumatic fever is an important cause of valvular heart
disease worldwide. In the United States (and Western Europe), cases of
acute rheumatic fever have been uncommon since the 1970s. However,
starting in 1987, an increase in cases has been observed.
Patients who have had an episode of rheumatic fever are at high risk of developing recurrent episodes of acute rheumatic fever. Patients who develop carditis are especially prone to similar episodes with subsequent attacks. Thus, secondary prevention of subsequent rheumatic fever recurrences is of great importance. Continuous antimicrobial prophylaxis has been shown to be effective. Anyone who has had rheumatic fever with or without carditis (including MS) should have prophylaxis for recurrent rheumatic fever. Lifelong prophylaxis is recommended for patients who have had carditis and residual valve disease and are likely to come in contact with populations with a high prevalence of streptococcal infections, such as teachers and day-care workers. Guidelines for primary and secondary prevention have been published by the AHA6 and are reproduced in the full text of these guidelines.
III. Specific Valve Lesions
A. Aortic Stenosis
Grading the Degree of Stenosis
The aortic valve area must be reduced to one fourth its
normal size before significant changes in the circulation occur.
Because the normal adult valve orifice is 
3.0 to 4.0
cm2, an area 0.75 to 1.0
cm2 is usually not considered severe AS. In large
patients, a valve area of 1.0 cm2 may be severely
stenotic, whereas a valve area of 0.7 cm2
may be adequate for a smaller patient.
The committee used a variety of hemodynamic and natural
history data to grade the degree of AS as mild (area >1.5
cm2), moderate (area >1.0 to 1.5
cm2), or severe (area
1.0cm2). When stenosis is
severe and cardiac output is normal, the mean transvalvular
pressure gradient is generally >50 mm Hg. Some patients with
severe AS remain asymptomatic, whereas others with only
moderate stenosis develop symptoms. Therapeutic decisions,
particularly those related to corrective surgery, are based largely on
the presence or absence of symptoms. Thus, the absolute valve area (or
transvalvular pressure gradient) is not usually the primary
determinant of the need for aortic valve replacement (AVR).
An ejection systolic murmur may be heard in the presence of a normal valve, one that is thickened and minimally calcified, and one that is stenotic. The 3 conditions must be distinguished.
Natural History
The natural history of AS in the adult consists of a
prolonged latent period in which morbidity and mortality are very low.
The rate of progression of the stenotic lesion has been
estimated in a variety of hemodynamic studies performed
largely in patients with moderate AS. Cardiac
catheterization and Doppler
echocardiographic studies indicate that some patients
exhibit a decrease in valve area of 0.1 to 0.3
cm2 per year; the average rate of change is
0.12 cm2 per year. The systolic
pressure gradient across the valve may increase by as much as 10 to
15 mm Hg per year. However, more than half of the reported
patients showed little or no progression over a 3- to 9-year period.
Although it appears that progression of AS can be more rapid in
patients with degenerative calcific disease than in those with
congenital or rheumatic disease, it is not possible to predict the rate
of progression in an individual patient.
Eventually, symptoms of angina, syncope, or heart failure develop after a long latent period, and the outlook changes dramatically. After onset of symptoms, average survival is <2 to 3 years. Thus, the development of symptoms identifies a critical point in the natural history of AS.
Many asymptomatic patients with severe AS develop symptoms
within a few years and require surgery. The incidence of angina,
dyspnea, or syncope in asymptomatic patients with
Doppler outflow velocities 4 m/s has been reported to be as high
as 38% after 2 years and 79% after 3 years. Therefore, patients with
severe AS require careful monitoring for development of symptoms and
progressive disease.
Sudden death is known to occur in patients with severe AS but has rarely been documented to occur without prior symptoms. Recent prospective echocardiographic studies provide important data on the rarity of sudden death in asymptomatic patients. Although sudden death does occasionally occur in the absence of preceding symptoms in patients with AS, it must be an uncommon event—probably <1% per year.
Management of the Asymptomatic Patient
Patients with the physical findings of AS should undergo selected
laboratory examinations, including an ECG, a chest x-ray, and an
echocardiogram. The 2-D echocardiogram is valuable for confirming the
presence of aortic valve disease and determining left ventricular (LV)
size and function, degree of hypertrophy, and presence of
other associated valve disease. In most patients, the severity of the
stenotic lesion can be defined with Doppler
echocardiographic measurements of a mean
transvalvular pressure gradient and a derived valve area as
discussed in the ACC/AHA Guidelines for the Clinical Application of
Echocardiography.2
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In some patients, it may be necessary to proceed with cardiac catheterization and coronary angiography at the time of initial evaluation. This is appropriate, for example, if there is a discrepancy between the clinical and echocardiographic examinations or if the patient is symptomatic and AVR is planned.
Exercise testing in adults with AS has been discouraged largely because of concerns about safety. Furthermore, when used to assess the presence or absence of coronary artery disease (CAD), the test has limited diagnostic accuracy. Certainly, exercise testing should not be performed in symptomatic patients. However, in asymptomatic patients, exercise testing is safe and may provide information not uncovered during the initial clinical evaluation. Exercise testing in asymptomatic patients should be performed only under the supervision of an experienced physician, with close monitoring of blood pressure and the ECG. Such testing can identify patients who have a limited exercise capacity or even exercise-induced symptoms despite a negative medical history. An abnormal hemodynamic response (eg, hypotension) in a patient with severe AS is sufficient reason to consider AVR.
The frequency of follow-up visits to the physician depends on the severity of valvular stenosis and in part on the presence of comorbid conditions. Recognizing that an optimal schedule for repeated medical examinations has not been defined, many physicians perform an annual history and physical examination on patients with mild AS. Those with moderate and severe AS should be examined more frequently. Patients should be advised to promptly report the development of any exertional chest discomfort, dyspnea, lightheadedness, or syncope.
Echocardiographic studies can be an important part of an integrated approach to the asymptomatic patient. Current understanding of the natural history of AS and indications for surgical intervention do not support the use of annual echocardiographic studies to assess changes in valve area. However, serial echocardiograms are helpful for assessing changes in LV hypertrophy and function. Therefore, in patients with severe AS, a yearly echocardiogram may be appropriate. In patients with moderate AS, serial studies every 2 years or so are satisfactory, and in patients with mild AS, serial studies can be performed every 5 years. Echocardiography should be performed more frequently if there is a change in clinical findings.
Recommendations for activity are based on the clinical examination, with special emphasis on the hemodynamic severity of the stenotic lesion. Recommendations regarding participation in competitive athletics have been published by the Task Force on Acquired Valvular Heart Disease of the 26th Bethesda Conference.7 Patients with severe AS should be advised to limit activity to relatively low levels.
Indications for Cardiac Catheterization
In patients with AS, the indications for cardiac
catheterization and angiography are to assess the
coronary circulation and confirm or clarify the clinical
diagnosis. In preparation for AVR, coronary angiography is
indicated in patients suspected of having CAD, as discussed in section
VIII. If the clinical and echocardiographic data are
typical of severe isolated AS, coronary angiography may be all
that is needed before AVR. Complete left- and right-heart
catheterization may be necessary to assess the
hemodynamic severity of AS if there is a discrepancy
between clinical and echocardiographic data or evidence
of associated valvular or congenital disease or
pulmonary hypertension.
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The pressure gradient across a stenotic valve is related to the valve orifice area and transvalvular flow. Thus, in the presence of depressed cardiac output, relatively low pressure gradients are frequently obtained in patients with severe AS. On the other hand, during exercise or other high-flow states, systolic gradients can be measured in minimally stenotic valves. For these reasons, complete assessment of AS requires (1) measurement of transvalvular flow, (2) determination of the transvalvular pressure gradient, and (3) calculation of the effective valve area. Careful attention to detail with accurate measurements of pressure and flow is important, especially in patients with low cardiac output or a low transvalvular pressure gradient.
Patients with severe AS and low cardiac output often present with only modest transvalvular pressure gradients (ie, <30 mm Hg). Such patients can be difficult to distinguish from those with low cardiac output and only mild to moderate AS. In both situations, the low-flow state and low pressure gradient contribute to a calculated effective valve area that can meet criteria for severe AS. The standard valve area formula is less accurate and is known to underestimate the valve area in low-flow states; under such conditions, it should be interpreted with caution. Although valve resistance is less sensitive to flow than valve area, resistance calculations have not been proved to be substantially better than valve area calculations.
In patients with low gradient stenosis and what appears to be moderate to severe AS, it may be useful to determine the transvalvular pressure gradient and calculate valve area and resistance during a baseline state and again during exercise or pharmacological (ie, dobutamine infusion) stress. Patients who do not have true, anatomically severe stenosis exhibit an increase in the valve area during an increase in cardiac output. In patients with severe AS, these changes may result in a calculated valve area that is higher than the baseline calculation but that remains in the severe range, whereas in patients without severe AS, the calculated valve area will fall outside the severe range with administration of dobutamine and indicate that severe AS is not present.
Indications for Aortic Valve Replacement
In the vast majority of adults, AVR is the only effective
treatment for severe AS. However, younger patients may be candidates
for valvotomy (see section VI.A.).
1. Symptomatic Patients.
Patients with angina, dyspnea, or syncope exhibit
symptomatic improvement and an increase in survival after
AVR. Outcome is similar in patients with normal LV function and those
with moderate depression of contractile function. The depressed
ejection fraction in many patients in this latter group is caused by
excessive afterload (afterload mismatch), and LV function improves
after AVR in such patients. If LV dysfunction is not caused by
afterload mismatch, then improvement in LV function and resolution of
symptoms may not be complete after valve replacement. Survival is still
improved in this setting with the possible exception of patients with
severe LV dysfunction caused by CAD. Therefore, in the absence of
serious comorbid conditions, AVR is indicated in virtually all
symptomatic patients with severe AS. However, patients with
severe LV dysfunction, particularly those with so-called low gradient
AS, represent a difficult management decision (see above). AVR
should not be performed in such patients when they do not have
anatomically severe stenosis. In patients with severe AS, even
those with a low transvalvular pressure gradient, AVR results
in hemodynamic improvement and better functional
status.
2. Asymptomatic Patients.
Management decisions in asymptomatic patients are more
controversial. The combined risk of surgery and late complications of a
prosthesis generally exceed the possibility of preventing
sudden death and prolonging survival in all asymptomatic
patients, as discussed previously. Despite these considerations, some
difference of opinion persists regarding indications for AVR in
asymptomatic patients. It is reasonable to attempt to
identify patients who may be at especially high risk of sudden death
without surgery, although data supporting this approach are limited.
Patients in this subgroup include those with an abnormal response to
exercise (eg, hypotension), LV systolic dysfunction or
marked/excessive LV hypertrophy, or evidence of severe AS.
However, it should be recognized that such "high-risk" patients are
rarely asymptomatic.
3. Patients Undergoing Coronary Artery Bypass Surgery.
Patients with severe AS, with or without symptoms, who
are undergoing coronary artery bypass surgery should undergo
AVR at the time of revascularization. Similarly,
patients with severe AS undergoing surgery on other valves (such as
mitral valve repair) or the aortic root should also undergo AVR as part
of the surgical procedure. Patients with moderate AS (for example,
gradient 30 mm Hg) may warrant AVR at the time of
coronary artery bypass surgery or surgery on the mitral valve
or aortic root. However, controversy persists regarding indications for
concomitant AVR at the time of coronary artery bypass surgery
in patients with milder forms of AS as discussed in section
VIII.D.
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Aortic Balloon Valvotomy
Percutaneous balloon aortic valvotomy has an
important role in treatment of adolescents and young adults with AS
(see section VI.A.) but a very limited role in older adults. Immediate
hemodynamic results include a moderate reduction in the
transvalvular pressure gradient, but the postvalvotomy
valve area is rarely >1.0 cm2. However, serious
complications occur with a frequency of >10%, and restenosis
and clinical deterioration occur within 6 to 12 months in most
patients. Therefore, in adults with AS, balloon valvotomy is not a
substitute for AVR.
Balloon valvotomy can play a temporary role in the management of some
symptomatic patients who are not initially candidates for
AVR. For example, patients with severe AS and refractory
pulmonary edema or cardiogenic shock may benefit from aortic
valvuloplasty as a "bridge" to surgery; an improved
hemodynamic state may reduce the risks of AVR.
Indications for palliative valvotomy in patients with serious comorbid
conditions are less well established, but most patients can expect
temporary relief of symptoms despite a very limited life expectancy.
Asymptomatic patients with severe AS who require urgent
noncardiac surgery may be candidates for valvotomy, but most such
patients can be successfully treated with more conservative
measures.
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Special Considerations in the Elderly
Because there is no effective medical therapy and balloon
valvotomy is not an acceptable alternative to surgery, AVR must be
considered in all elderly patients who have symptoms caused by AS. AVR
is technically possible at any age, but the decision to proceed with
such surgery depends on many factors, including the patient's wishes
and expectations.
In addition to the confounding effects of CAD and the potential for stroke, other considerations are specific to older patients. For example, a narrow LV outflow tract and small aortic annulus sometimes present in elderly women may require enlargement of the annulus. Heavy calcification of the valve, annulus, and aortic root may require debridement. Occasionally, a composite valve-aortic graft is needed. Excessive or inappropriate hypertrophy associated with valvular stenosis can be a marker for perioperative morbidity and mortality. Preoperative recognition of elderly patients with marked LV hypertrophy followed by appropriate perioperative management may substantially reduce this morbidity and mortality.
B. Aortic Regurgitation
1. Acute Aortic Regurgitation
In acute severe aortic regurgitation (AR), the
sudden large regurgitant volume is imposed on a left ventricle of
normal size that has not had time to accommodate to the volume
overload. LV end-diastolic and left atrial pressures may
increase rapidly and dramatically. The Frank-Starling mechanism is
used, but the inability of the ventricle to develop compensatory
chamber dilatation acutely results in a decrease in forward stroke
volume. Although tachycardia develops as a compensatory
mechanism to maintain cardiac output, this is often insufficient.
Hence, patients frequently present with pulmonary edema
and/or cardiogenic shock.
Diagnosis
Many of the characteristic physical findings of chronic AR are
modified or absent when valvular regurgitation
is acute, which may lead to underestimation of its severity.
Echocardiography is indispensable in confirming the
presence and severity of valvular
regurgitation, determining its etiology, estimating the
degree of pulmonary hypertension (if tricuspid
regurgitation [TR] is present), and determining
whether there is rapid equilibration of aortic and LV
diastolic pressure. Evidence for rapid pressure
equilibration includes short AR diastolic half-time (<300
ms), short mitral deceleration time (<150 ms), or premature closure of
the mitral valve.
Acute AR caused by aortic root dissection is a surgical emergency that requires prompt identification and management. Transesophageal echocardiography is indicated when aortic dissection is suspected. If the diagnosis remains uncertain, cardiac catheterization and aortography should be performed. Coronary angiography is an important component of the evaluation of aortic dissection and acute AR and should be performed, provided that it does not delay urgent surgery.
Treatment
Death from pulmonary edema, ventricular
arrhythmias, electromechanical dissociation, or circulatory
collapse is common in acute severe AR, even with intensive medical
management. Early surgical intervention is recommended. Nitroprusside
and possibly inotropic agents such as dopamine or
dobutamine to augment forward flow and reduce LV
end-diastolic pressure may be helpful to treat the patient
temporarily before surgery. Intra-aortic balloon counterpulsation is
contraindicated. Although ß-blockers are often used in treating
aortic dissection, they should be used cautiously, if at all, in the
setting of acute AR because they will block compensatory
tachycardia.
2. Chronic Aortic Regurgitation
Chronic AR represents a condition of combined volume
overload and pressure overload. As the disease progresses, recruitment
of preload reserve and compensatory hypertrophy permit the
ventricle to maintain normal ejection performance despite the
elevated afterload. The majority of patients remain
asymptomatic throughout this compensated phase, which may
last for decades. Vasodilator therapy has the potential to reduce the
hemodynamic burden in such patients.
For the purposes of subsequent discussion, patients with normal LV systolic function are defined as those with normal LV ejection fraction at rest. It is recognized that overall LV function is usually not "normal" in chronic severe AR and that the hemodynamic abnormalities noted above may be considerable. It is also recognized that the transition to LV systolic dysfunction represents a continuum and that no single hemodynamic measurement represents the absolute boundary between normal LV systolic function and LV systolic dysfunction.
The balance between afterload excess, preload reserve, and hypertrophy cannot be maintained indefinitely in many patients, and afterload mismatch and/or depressed contractility ultimately result in a reduction in ejection fraction, first into the low normal range and then below normal. At this point in the natural history, patients often develop dyspnea, which is related to declining systolic function or elevated filling pressures. However, this transition may be much more insidious, and it is possible for patients to remain asymptomatic until severe LV dysfunction has developed.
LV systolic dysfunction (defined as an ejection fraction below normal at rest) is initially a reversible phenomenon predominantly related to afterload excess, and full recovery of LV size and function is possible with AVR. With time, during which the ventricle develops progressive chamber enlargement and a more spherical geometry, depressed myocardial contractility predominates over excessive loading as the cause of progressive systolic dysfunction. This can progress to the extent that the full benefit of surgical correction of the regurgitant lesion in terms of recovery of LV function and improved survival can no longer be achieved.
A large number of studies have identified LV systolic function and end-systolic size as the most important determinants of survival and postoperative LV function in patients undergoing AVR for chronic AR.
Several factors are associated with worse functional and survival results after AVR for chronic AR in patients with preoperative LV systolic dysfunction. These include severity of symptoms, the severity of LV systolic dysfunction, and the duration of preoperative systolic dysfunction. Taken together, these observations support the recommendation that patients with evidence of LV systolic dysfunction, even if asymptomatic or minimally symptomatic, should undergo AVR before more severe symptoms or more severe ventricular dysfunction develop.
Natural History
1. Asymptomatic Patients With Normal Left
Ventricular Function.
The current recommendations are derived from 7 published series
involving a total of 490 patients with a mean follow-up period of 6.4
years. The rate of progression to symptoms and/or LV systolic
dysfunction averaged 4.3% per year. Sudden death occurred in 6 of the
490 patients, an average mortality rate of <0.2% per year. Six of the
7 studies reported the rate of development of
asymptomatic LV dysfunction; 36 of a total of 463 patients
developed depressed systolic function at rest without symptoms
during a mean 5.9-year follow-up period, a rate of 1.3% per year.
2. Asymptomatic Patients With Depressed
Systolic Function.
The limited data in asymptomatic patients with
depressed LV ejection fraction indicate that the majority develop
symptoms warranting surgery within 2 to 3 years. The average rate of
symptom onset in such patients is >25% per year.
3. Symptomatic Patients.
There are no recent large-scale studies of the natural history of
symptomatic patients with chronic AR, because the onset of
angina or significant dyspnea is usually an indication for valve
replacement. Data from the presurgical era indicate that
symptomatic patients have a poor outcome with medical
therapy, which is analogous to that of patients with
symptomatic AS, with mortality rates of >10% per year in
patients with angina pectoris and >20% per year in those with heart
failure.
Diagnosis and Initial Evaluation of the
Asymptomatic Patient
The diagnosis of chronic severe AR can usually be made on
the basis of physical examination. The chest x-ray and ECG are helpful
in evaluating overall heart size and rhythm, evidence of LV
hypertrophy, and evidence of conduction disorders.
Echocardiography is indicated to confirm the
diagnosis of AR if there is an equivocal diagnosis based on physical
examination; assess the cause of AR as well as valve morphology;
provide a semiquantitative estimate of severity of
regurgitation; assess LV dimension, mass, and
systolic function; and assess aortic root size. In
asymptomatic patients with preserved systolic
function, these initial measurements represent the baseline
information with which future serial measurements can be
compared.
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If the patient is asymptomatic and leads an active lifestyle and the echocardiogram is of good quality, no other testing is necessary. If the patient has severe AR and is sedentary or has equivocal symptoms, exercise testing is helpful to assess functional capacity, symptomatic responses, and hemodynamic effects of exercise. If the echocardiogram is of insufficient quality to assess LV function, radionuclide angiography should be used in asymptomatic patients to measure LV ejection fraction at rest and estimate LV volumes. When patients are symptomatic on initial evaluation, it is reasonable to proceed directly with cardiac catheterization and angiography if the echocardiogram is of insufficient quality to assess LV function or severity of AR.
The exercise ejection fraction and change in ejection fraction
from rest to exercise are often abnormal, even in
asymptomatic patients. However, these have not been proved
to have independent diagnostic or prognostic value when LV
function at rest and severity of LV volume overload by
echocardiography are already known.
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Asymptomatic patients with normal LV systolic function may participate in all forms of normal daily physical activity, including mild-intensity forms of exercise and in some cases competitive athletics. Isometric exercise should be avoided. Recommendations for participation in competitive athletics were published by the Task Force on Acquired Valvular Heart Disease of the 26th Bethesda Conference.7
Medical Therapy
Therapy with vasodilating agents is designed to improve forward
stroke volume and reduce regurgitant volume. These effects should
translate into reductions in LV end-diastolic volume, wall
stress, and afterload, resulting in preservation of LV systolic
function and reduction in LV mass. These effects have been observed in
small numbers of patients who received oral therapy with
hydralazine and nifedipine for 1 to 2 years. Less
consistent results have been reported with
angiotensin converting enzyme (ACE) inhibitors,
depending on the degree of reduction in arterial pressure
and end-diastolic volume.
Only 1 study, in which long-acting nifedipine was compared with digoxin therapy in 143 patients followed up for 6 years, has evaluated whether vasodilating therapy alters the long-term natural history of chronic asymptomatic AR in a favorable manner. Over 6 years, long-acting nifedipine reduced the need for valve replacement from 34% to 15%. Moreover, when patients who received nifedipine did undergo AVR because of symptoms or impaired systolic function, all survived surgery, and LV size and function improved considerably in all patients.
The goal of vasodilator therapy is to reduce systolic blood pressure. Drug dosage should be increased until there is a measurable decrease in systolic blood pressure or the patient develops side effects. It is rarely possible to decrease systolic blood pressure to normal because of the increased LV stroke volume, and drug dosage should not be increased excessively in an attempt to achieve this goal. Vasodilator therapy is of unknown benefit and is not indicated in patients with normal blood pressure and/or normal cavity size.
Vasodilator therapy is not recommended for
asymptomatic patients with mild AR and normal LV function
in the absence of systemic hypertension, as these patients have an
excellent outcome with no therapy. Vasodilator therapy is not an
alternative to surgery for asymptomatic or
symptomatic patients with severe AR and LV systolic
dysfunction. Whether symptomatic patients who have
preserved systolic function can be safely treated with
aggressive medical management and whether aggressive medical management
is as good or better than AVR have not been determined. It is
recommended that symptomatic patients undergo surgery
rather than long-term medical therapy.
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Serial Testing
In general, the stability and chronicity of the regurgitant lesion
and the LV response to the volume load must be established when the
patient first presents to the physician, especially if AR is
moderate to severe. If the chronic nature of the lesion is uncertain
and the patient does not present initially with 1 or more
indications for surgery, the physical examination and echocardiogram
should be repeated 2 to 3 months after the initial evaluation to ensure
that a subacute process with rapid progression is not under way.
Once the chronicity and stability of the process have been established,
the frequency of clinical reevaluation and repeat noninvasive testing
depends on severity of valvular regurgitation,
degree of LV dilatation, level of systolic function, and
whether previous serial studies have revealed progressive changes in LV
size or function. In most patients, serial testing during the long-term
follow-up period should include a detailed history, physical
examination, and echocardiography. Serial chest
x-rays and ECGs are of less value but are helpful in selected
patients.
Asymptomatic patients with mild AR, little or no LV dilatation, and normal LV systolic function can be seen on a yearly basis with instructions to alert the physician if symptoms develop in the interim. Yearly echocardiography is not necessary unless there is clinical evidence that regurgitation has worsened. Routine echocardiography can be performed every 2 to 3 years in such patients.
Asymptomatic patients with normal systolic function but severe AR and significant LV dilatation (end-diastolic dimension >60 mm) require more frequent and careful reevaluation, with a history and physical examination every 6 months and echocardiography every 6 to 12 months, depending on severity of dilatation and stability of measurements. If the patient's condition is stable, echocardiographic measurements are not required more frequently than every 12 months. It is reasonable to obtain serial echocardiograms as often as every 4 to 6 months in patients with more advanced LV dilatation (end-diastolic dimension >70 mm or end-systolic dimension >50 mm) for whom the risk of developing symptoms or LV dysfunction ranges from 10% to 20% per year. Serial chest x-rays and ECGs are of less value but are helpful in selected patients.
Chronic AR may develop from disease processes involving the proximal ascending aorta. In patients with aortic root dilatation, serial echocardiograms are indicated to evaluate aortic root size as well as LV size and function.
Repeat echocardiograms are also recommended when the patient has onset of symptoms, there is an equivocal history of changing symptoms or exercise tolerance, or there are clinical findings suggesting worsening regurgitation or progressive LV dilatation. Patients with echocardiographic evidence of progressive ventricular dilatation or declining systolic function have a greater likelihood of developing symptoms or LV dysfunction and should have more frequent follow-up examinations (every 6 months) than those with stable LV function.
In some centers with expertise in nuclear cardiology, serial radionuclide ventriculography to assess LV volume and function at rest may be an accurate and cost-effective alternative to serial echocardiography. However, there is no justification for routine serial testing with both echocardiography and radionuclide ventriculography. Serial radionuclide ventriculograms are also recommended in patients with suboptimal echocardiograms and when there is a discrepancy between clinical assessment and echocardiographic data. In centers with specific expertise in cardiac MRI, serial MRI may be performed in place of radionuclide angiography for the indications listed above.
Indications for Cardiac Catheterization
Cardiac catheterization is not required in
patients with chronic AR unless there are questions about the severity
of AR, hemodynamic abnormalities, or LV
systolic dysfunction despite physical examination and
noninvasive testing or unless AVR is contemplated and there is a need
to assess coronary anatomy (see section VIII).
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Hemodynamic and angiographic assessment of severity of AR and LV function may be necessary in some patients being considered for surgery when there are conflicting data between clinical assessment and noninvasive tests. Hemodynamic measurements during exercise are occasionally helpful in determining the effect of AR on LV function or in making decisions about medical or surgical therapy. In selected patients with severe AR, borderline or normal LV systolic function, and LV chamber enlargement that is approaching the threshold for operation (defined below), measurement of cardiac output and LV filling pressures at rest and during exercise with a right-heart catheter may be valuable for identifying patients with severe hemodynamic abnormalities in whom surgery is warranted.
Indications for Aortic Valve Replacement
In patients with pure chronic AR, AVR should be considered only if
AR is severe. Patients with only mild AR are not candidates for valve
replacement, and if they have symptoms or LV dysfunction, other causes
should be considered, such as CAD, hypertension, or
cardiomyopathic processes. The following discussion
applies only to those patients with pure severe AR.
1. Symptomatic Patients With Normal Left
Ventricular Systolic Function.
AVR is indicated in patients with normal systolic function
(defined as ejection fraction 0.50 at rest) who have New York Heart
Association (NYHA) functional Class III or IV symptoms or Canadian
Heart Association functional Class II to IV angina pectoris. In many
patients with NYHA functional Class II dyspnea, the cause of symptoms
is often unclear, and it may be difficult to differentiate the effects
of deconditioning or aging from true cardiac symptoms. In such
patients, exercise testing may be valuable. If the cause of these mild
symptoms is uncertain and if they are not severe enough to interfere
with the patient's lifestyle, a period of observation may be
reasonable. However, new onset of mild dyspnea has different
implications in severe AR, especially in patients with increasing LV
chamber size or evidence of declining LV systolic function into
the low normal range. Mild symptoms are an indication for AVR in such
patients.
2. Symptomatic Patients With Left
Ventricular Dysfunction.
Patients with NYHA functional Class II, III, or IV symptoms and
mild to moderate LV systolic dysfunction (ejection fraction
0.25 to 0.49) should undergo AVR. Patients with functional Class IV
symptoms have worse postoperative survival rates and lower likelihood
of recovery of systolic function than patients with less severe
symptoms, but AVR will improve ventricular loading
conditions and expedite subsequent management of LV dysfunction.
Symptomatic patients with advanced LV dysfunction (ejection fraction <0.25 and/or end-systolic dimension >60 mm) present difficult management issues, as many have developed irreversible myocardial changes. AVR should be more strongly considered in patients with NYHA functional Class II and III symptoms, especially if (1) symptoms and evidence of LV dysfunction are of recent onset and (2) intensive short-term therapy with vasodilators, diuretics, and/or intravenous positive inotropic agents results in substantial improvement in hemodynamics or systolic function. However, even in patients with NYHA functional Class IV symptoms and ejection fraction <0.25, the high risks associated with AVR and subsequent medical management of LV dysfunction are usually a better alternative than the higher risks of long-term medical management alone.
3. Asymptomatic Patients.
AVR in asymptomatic patients remains a controversial
topic, but it is generally agreed that valve replacement is indicated
in patients with LV systolic dysfunction. As noted previously,
for the purposes of these guidelines, LV systolic dysfunction
is defined as an ejection fraction below normal at rest, ie, 0.50. It
is recognized that this lower limit is technique dependent and may vary
among institutions.
Valve replacement is also recommended in patients with severe LV dilatation (end-diastolic dimension >75 mm or end-systolic dimension >55 mm), even if ejection fraction is normal. Such patients appear to represent a high-risk group with an increased incidence of sudden death, and thus far the results of valve replacement have been excellent. In contrast, postoperative mortality is considerable once patients with severe LV dilatation develop symptoms and/or LV systolic dysfunction.
Women tend to develop symptoms and/or LV dysfunction with less LV
dilatation than men; this appears to be related to body size, as these
differences are not apparent when LV dimensions are corrected for body
surface area. Hence, LV dimensions alone may be misleading in small
patients of either gender, and the threshold values of
end-diastolic and end-systolic dimension
recommended for AVR in asymptomatic patients (75 mm
and 55 mm, respectively) may need to be reduced for such patients.
There are no data from which to derive guidelines for LV dimensions
corrected for body size, and clinical judgment is required.
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Concomitant Aortic Root Disease
In addition to causing acute AR, diseases of the proximal aorta
may also contribute to chronic AR. If AR is mild and/or the left
ventricle is only mildly dilated, management should focus on treating
the underlying aortic root disease, which is beyond the scope of these
guidelines. However, in many patients, AR may be severe, in which case
decisions about medical therapy and timing of surgery must take into
account both conditions. In general, AVR and aortic root reconstruction
are indicated in patients with disease of the proximal aorta and AR of
any severity when the degree of aortic root dilatation is 50 mm
by echocardiography.
Evaluation of Patients After Aortic Valve Replacement
After AVR, careful follow-up is necessary during the early and
long-term postoperative course to evaluate prosthetic valve
function and assess LV function, as discussed in detail in section
VII.C. An echocardiogram should be performed soon after surgery to
assess the results of surgery on LV size and function and to serve as a
baseline for comparison of subsequent echocardiograms. In the first few
weeks after surgery, there is little change in LV systolic
function, and ejection fraction may deteriorate, compared with
preoperative values, because of the reduced preload. A better predictor
of subsequent LV systolic function is the reduction in LV
end-diastolic dimension, which declines significantly
within the first week or two of operation. This is an excellent marker
of the functional success of AVR, as the magnitude of early reduction
in end-diastolic dimension after operation correlates with
the magnitude of late increase in ejection fraction.
Patients with persistent LV dilatation on the initial postoperative echocardiogram should receive the same treatment, including ACE inhibitors, as any other patient with symptomatic or asymptomatic LV dysfunction.
C. Mitral Stenosis
The normal mitral valve area is 4.0 to 5.0 cm2. Narrowing of the valve area to <2.5 cm2 must occur before development of symptoms.
A mitral valve area >1.5 cm2 usually does not produce symptoms at rest. However, if there is an increase in transmitral flow or a decrease in the diastolic filling period, there will be a rise in left atrial pressure and development of symptoms. Thus, the first symptoms of dyspnea in patients with mild MS are usually precipitated by exercise, emotional stress, infection, pregnancy, or atrial fibrillation with a rapid ventricular response.
Natural History
MS is a continuous, progressive, lifelong disease, usually
consisting of a slow, stable course in the early years and progressive
acceleration later in life. In developed countries, there is a long
latent period of 20 to 40 years from the occurrence of rheumatic fever
to onset of symptoms. Once symptoms develop, there is another period of
almost a decade before symptoms become disabling. Overall, the 10-year
survival of untreated patients with MS is 50% to 60%, depending on
symptoms at presentation. In the asymptomatic
or minimally symptomatic patient, survival is >80% at 10
years, with 60% of patients having no progression of symptoms.
However, once significant limiting symptoms occur, there is a dismal
10-year survival rate of 0% to 15%, and when there is severe
pulmonary hypertension, mean survival drops to <3 years.
Mortality of untreated patients with MS is caused by progressive heart
failure in 60% to 70%, systemic embolism in 20% to 30%,
pulmonary embolism in 10%, and infection in 1% to 5%.
Evaluation and Management of the Asymptomatic Patient
The diagnosis of MS should be based on the history, physical
examination, chest x-ray, and ECG. The diagnostic tool of
choice in the evaluation of a patient with MS is 2-D and Doppler
echocardiography. The morphological appearance of
the mitral valve apparatus should be assessed by 2-D
echocardiography, including leaflet mobility,
leaflet thickness, leaflet calcification, subvalvular fusion,
and appearance of the commissures. These features may be important when
considering the timing and type of intervention to be performed.
Chamber size and function as well as other structural valvular,
myocardial, or pericardial abnormalities should also be assessed.
The hemodynamic severity of the obstruction
should be assessed with Doppler
echocardiography. The mean transmitral gradient can
be accurately and reproducibly measured from the continuous wave
Doppler signal across the mitral valve with the modified Bernoulli
equation, and the mitral valve area can be noninvasively measured by
either the diastolic half-time method or the continuity
equation. The half-time method may be inaccurate in patients with
abnormalities of left atrial or LV compliance, those with associated
AR, and those with previous mitral valvotomy. Doppler
echocardiography should also be used when possible
to estimate pulmonary artery systolic pressure from the
TR velocity signal and assess severity of concomitant MR or AR. Formal
hemodynamic exercise testing can be done noninvasively
by either a supine bicycle or upright treadmill with Doppler
recordings of transmitral and tricuspid velocities. This allows
measurement of both the transmitral gradient and pulmonary
artery systolic pressure at rest and with exercise.
Dobutamine stress testing with Doppler
recordings may also be performed.
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In the asymptomatic patient who has documented mild MS (valve area >1.5 cm2 and mean gradient <5 mm Hg), no further evaluation is needed on the initial workup. These patients usually remain stable for many years. If MS is more significant, further evaluation should be considered if the mitral valve morphology appears to be suitable for mitral valvotomy with pliable, noncalcified valves with little or no subvalvular fusion and no calcification in the commissures. Patients with moderate pulmonary hypertension at rest (pulmonary artery systolic pressure >50 mm Hg) and pliable mitral valve leaflets may be considered for percutaneous mitral valvotomy even if they deny symptoms. In patients who lead a sedentary lifestyle, a hemodynamic exercise test with Doppler echocardiography is useful. Objective limitation of exercise tolerance with a rise in transmitral gradient >15 mm Hg and pulmonary artery systolic pressure >60 mm Hg may be an indication to consider percutaneous valvotomy if mitral valve morphology is suitable.
All patients should be informed that any change in symptoms warrants reevaluation. In the asymptomatic patient, yearly reevaluation is recommended; at this time, a history, physical examination, chest x-ray, and ECG should be obtained. A yearly echocardiogram is not recommended unless there is a change in clinical status. Ambulatory ECG monitoring to detect paroxysmal atrial fibrillation is indicated in patients with palpitations.
Medical Therapy
1. General Principles.
Because MS is primarily caused by rheumatic fever, prophylaxis against
rheumatic fever is recommended. Appropriate endocarditis prophylaxis is
also recommended. Patients who have more than a mild degree of MS
should be counseled to avoid unusual physical stresses. Agents with
negative chronotropic properties, such as ß-blockers or calcium
channel blockers, may be of benefit in patients with sinus rhythm who
have exertional symptoms if the symptoms occur with high heart rates.
Salt restriction and intermittent administration of a diuretic
are useful if there is evidence of pulmonary vascular
congestion. Digitalis does not benefit patients with MS in sinus rhythm
unless there is left and/or right ventricular
dysfunction.
2. Atrial Fibrillation.
Atrial fibrillation develops in 30% to 40% of patients with
symptomatic MS. Significant hemodynamic
consequences may result from acute development of atrial fibrillation,
with loss of atrial contribution to LV filling, and from the rapid
ventricular rate. Atrial fibrillation occurs more commonly
in older patients and is associated with a poorer prognosis, with a
10-year survival rate of 25% compared with 46% in patients who remain
in sinus rhythm. The risk of arterial embolization,
especially stroke, is significantly increased in patients with atrial
fibrillation. Treatment of an acute episode of rapid atrial
fibrillation consists of anticoagulation with heparin and control of
the heart rate response. Intravenous digoxin, calcium
channel blockers, or ß-blockers should be used to control
ventricular response. If there is
hemodynamic instability, electrical cardioversion
should be undertaken urgently, with intravenous heparin
before, during, and after the procedure. Patients who have been in
atrial fibrillation >24 to 48 hours without anticoagulation are
at an increased risk for embolic events after cardioversion, but
patients may also have an embolic event with <24 hours of atrial
fibrillation. The decision to proceed with elective cardioversion
depends on multiple factors, including duration of atrial fibrillation,
hemodynamic response to onset of atrial fibrillation,
documented history of prior episodes of atrial fibrillation, and
history of prior embolic events. If the decision has been made to
proceed with elective cardioversion in a patient who has had documented
atrial fibrillation for >24 to 48 hours and who has not been on
long-term anticoagulation, 1 of 2 approaches is recommended, based on
data from patients with nonrheumatic atrial fibrillation. The first is
anticoagulation with warfarin for 3 weeks, followed by elective
cardioversion. The second is anticoagulation with heparin and
transesophageal echocardiography to
look for left atrial thrombus. In the absence of left atrial thrombus,
cardioversion is performed with intravenous heparin before,
during, and after the procedure. It is important to continue
anticoagulation after cardioversion to prevent thrombus formation
caused by atrial mechanical inactivity and to then maintain the patient
on long-term warfarin unless there is a strong contraindication to
anticoagulation. Controversy surrounds whether
percutaneous mitral valvotomy should be performed in
patients with new-onset atrial fibrillation and moderate to severe MS
who are otherwise asymptomatic.
3. Prevention of Systemic Embolization.
Systemic embolization may occur in 10% to 20% of patients with MS.
The risk of embolization is related to age, the presence of atrial
fibrillation, and history of previous embolic events. One third of
embolic events occur 1 month after onset of atrial fibrillation, and
two thirds occur within 1 year. The frequency of embolic events does
not seem to be related to severity of MS, cardiac output, size of left
atrium, or presence of symptoms. An embolic event may thus be the
initial manifestation of MS. In patients who have experienced an
embolic event, the frequency of recurrence is as high as 15 to
40 events per 100 patient months. There are no data to support the
concept that oral anticoagulation is beneficial in patients with MS who
have not had atrial fibrillation or an embolic event. It is
controversial whether patients who have not had atrial fibrillation or
an embolic event and who might be at higher risk for future embolic
events (ie, severe stenosis or enlarged left atrium) should be
considered for long-term warfarin therapy.
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Physical Activity and Exercise
The 26th Bethesda Conference on Recommendations for Determining Eligibility for Competition in Athletes With Cardiovascular Abnormalities has published guidelines for patients with MS who wish to engage in competitive athletics.7
Evaluation of the Symptomatic Patient
Patients who develop symptoms should undergo evaluation with a
history, physical examination, ECG, chest x-ray, and
echocardiography to evaluate mitral valve
morphology, mitral valve hemodynamics, and
pulmonary artery pressure. Patients with NYHA functional Class
II symptoms and moderate or severe stenosis (mitral valve area
1.5 cm2 or mean gradient 5 mm Hg) may
be considered for mitral balloon valvotomy if they have suitable mitral
valve morphology. Patients with NYHA functional Class III or IV
symptoms and evidence of severe MS have a poor prognosis if left
untreated, and intervention with either balloon valvotomy or surgery
should be considered.
A subset of patients have significant limiting symptoms yet resting
hemodynamics that do not indicate moderate to severe
MS. If there is a discrepancy between symptoms and
hemodynamic data, formal exercise testing or
dobutamine stress testing may be useful to differentiate
symptoms caused by MS from other causes. Exercise tolerance, heart rate
and blood pressure response, transmitral gradient, and
pulmonary artery pressure can be obtained at rest and during
exercise. This can usually be accomplished by either supine bicycle or
upright exercise with Doppler recording of TR and
transmitral velocities. Right- and left-heart
catheterization with exercise may also be helpful.
Patients who are symptomatic with a significant elevation
of pulmonary artery pressure (>60 mm Hg), mean
transmitral gradient (>15 mm Hg), or pulmonary artery
wedge pressure (25 mm Hg) on exertion have
hemodynamically significant MS and should be considered
for further intervention. Alternatively, patients who do not manifest
elevation in pulmonary artery, pulmonary artery wedge,
or transmitral pressures coincident with development of exertional
symptoms most likely would not benefit from intervention on the mitral
valve.
Indications for Cardiac Catheterization
In most instances, Doppler measurements of transmitral
gradient, valve area, and pulmonary pressure correlate well
with each other. Catheterization is indicated to assess
hemodynamics when there is a discrepancy between
Doppler-derived hemodynamics and the clinical
status of a symptomatic patient. Absolute left- and
right-sided pressure measurements should be obtained by
catheterization when there is elevation of
pulmonary artery pressure out of proportion to mean gradient
and valve area. Catheterization including left
ventriculography (to evaluate severity of MR) is indicated when there
is a discrepancy between Doppler-derived mean gradient and valve
area. Coronary angiography may be required in selected patients
who may need to undergo intervention (see section VIII).
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Indications for Surgical or Percutaneous Valvotomy
With the development of cardiopulmonary bypass in the 1960s, open mitral commissurotomy and replacement of the mitral valve became the surgical procedures of choice for treatment of MS. Percutaneous mitral balloon valvotomy emerged in the mid 1980s. This procedure has become an accepted alternative to surgical approaches in selected patients. The procedure itself is technically challenging and involves a steep learning curve. There is a higher success rate and lower complication rate in experienced high-volume centers. Thus, results of the procedure are highly dependent on the experience of the operators, which must be taken into consideration when making recommendations for proceeding with this technique.
The immediate results of percutaneous mitral
valvotomy are similar to those of mitral commissurotomy. The mean valve
area usually doubles (from 1.0 cm2 to 2.0
cm2), with a 50% to 60% reduction in
transmitral gradient. Overall, 80% to 95% of patients may have a
successful procedure, which is defined as a mitral valve area >1.5
cm2 and a decrease in left atrial pressure to
18 mm Hg in the absence of complications. The most common acute
complications reported in large series include severe MR, which occurs
in 2% to 10%, and a residual atrial septal defect. A large atrial
septal defect (>1.5:1 left-to-right shunt) occurs in up to 12% of
patients with the double balloon technique and in <5% with the Inoue
balloon technique. Smaller atrial septal defects may be detected by
transesophageal echocardiography in
larger numbers of patients. Less frequent complications include
perforation of the left ventricle (0.5% to 4.0%), embolic events
(0.5% to 3%), and myocardial infarction (0.3% to 0.5%). The
mortality for patients who undergo balloon valvotomy in larger series
has ranged from 1% to 2%; however, with increasing experience in the
procedure, percutaneous mitral valvotomy can be done in
selected patients with a mortality of <1%.
Follow-up information after percutaneous balloon valvotomy is limited. Event-free survival (freedom from death, repeat valvotomy, or mitral valve replacement) overall is 50% to 65% over 3 to 7 years, with an event-free survival of 80% to 90% in patients with favorable mitral valve morphology. More than 90% of patients free of events remain in NYHA functional Class I or II after percutaneous mitral valvotomy. Randomized trials have compared percutaneous balloon valvotomy with both closed and open surgical commissurotomy. There was no significant difference in acute hemodynamic results or complication rate between percutaneous mitral valvotomy and surgery, and early follow-up data indicate no difference in hemodynamics, clinical improvement, or exercise time. However, longer-term follow-up studies at 3 to 7 years indicate more favorable hemodynamic and symptomatic results with percutaneous balloon valvotomy than with closed commissurotomy and results equivalent to those of open commissurotomy.
The immediate results, acute complications, and follow-up results of percutaneous balloon valvotomy depend on multiple factors. It is of utmost importance that this procedure be performed in centers with skilled, experienced operators. Other factors include age, NYHA functional class, severity of stenosis, LV end-diastolic pressure, cardiac output, and pulmonary artery wedge pressure. The underlying mitral valve morphology is the most important factor in determining outcome, and patients with valvular calcification, thickened fibrotic leaflets with decreased mobility, and subvalvular fusion have a higher incidence of acute complications and a higher rate of recurrent stenosis on follow-up. In patients with noncalcified pliable valves and no calcium in the commissures, the procedure can be performed with a high success rate (>90%), low complication rate (<2% to 3%), and sustained improvement in 80% to 90% over a 3- to 7-year follow-up period.
Relative contraindications to percutaneous balloon valvotomy include the presence of a left atrial thrombus and significant (3+ to 4+) MR. Transesophageal echocardiography is frequently performed before the procedure to determine the presence of left atrial thrombus, specifically examining the left atrial appendage. If a thrombus is found, 3 months of anticoagulation with warfarin may result in resolution of the thrombus.
In centers with skilled, experienced operators,
percutaneous balloon valvotomy should be considered the
initial procedure of choice for symptomatic patients with
moderate to severe MS who have a favorable valve morphology in the
absence of significant MR or a left atrial thrombus. In
asymptomatic patients with a favorable valve morphology,
percutaneous mitral valvotomy may be considered if
there is evidence of a hemodynamic effect on left
atrial pressure (new-onset atrial fibrillation) or pulmonary
circulation (pulmonary artery pressure >50 mm Hg at rest
or >60 mm Hg with exercise). The strength of evidence for this
recommendation is low because there are no data comparing the results
of percutaneous balloon valvotomy and medical therapy
in such patients. It is controversial whether severely
symptomatic patients with less favorable valve morphology
should undergo this catheter-based procedure. Although there is a
higher acute complication rate and lower event-free survival
(approximately 50% at 5 years in these patients, compared with 80% to
90% in patients with favorable valve morphology), this must be weighed
against the risks and potential complications of surgical mitral valve
replacement.
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Indications for Mitral Valve Replacement
Mitral valve replacement (MVR) is an accepted surgical procedure for patients with severe MS who are not candidates for surgical commissurotomy or percutaneous mitral valvotomy. The risk of MVR is dependent on multiple factors, including functional status, age, LV function, cardiac output, concomitant medical problems, and concomitant CAD. In the young, healthy person, MVR can be performed with a risk of <5%. However, in the older patient with concomitant medical problems or pulmonary hypertension at systemic levels, the risk of MVR may be 10% to 20%.
If there is significant calcification, fibrosis, and subvalvular fusion of the mitral valve apparatus, commissurotomy or percutaneous balloon valvotomy is less likely to be successful, and MVR will be necessary. Given the risk of MVR and the potential long-term complications of a prosthetic valve, there are stricter indications for mitral valve operation in these patients with calcified fibrotic valves. For the patient with NYHA functional Class III symptoms due to severe MS or combined MS/MR, MVR results in excellent symptomatic improvement. Postponement of surgery until the patient reaches the functional Class IV symptomatic state should be avoided because operative mortality is high and long-term outcome suboptimal. However, if the patient presents in NYHA functional Class IV heart failure, surgery should not be denied because the outlook without surgical intervention is grave. It is controversial whether asymptomatic or mildly symptomatic patients with severe MS (valve area <1 cm2) and seve