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b. Indications for Mitral Valve Operation
Class I
1. MV surgery is recommended for the symptomatic
patient with acute severe MR.* (Level of Evidence: B)
2. MV surgery is beneficial for patients with chronic
severe MR* and NYHA functional class II, III, or IV
symptoms in the absence of severe LV dysfunction
(severe LV dysfunction is defined as ejection fraction
less than 0.30) and/or end-systolic dimension greater
than 55 mm. (Level of Evidence: B)
3. MV surgery is beneficial for asymptomatic patients
with chronic severe MR* and mild to moderate LV
dysfunction, ejection fraction 0.30 to 0.60, and/or
end-systolic dimension greater than or equal to 40
mm. (Level of Evidence: B)
4. MV repair is recommended over MV replacement
in the majority of patients with severe chronic MR*
who require surgery, and patients should be referred
to surgical centers experienced in MV repair.
(Level of Evidence: C)
Class IIa
1. MV repair is reasonable in experienced surgical centers
for asymptomatic patients with chronic severe
MR* with preserved LV function (ejection fraction
greater than 0.60 and end-systolic dimension less
than 40 mm) in whom the likelihood of successful
repair without residual MR is greater than 90%.
(Level of Evidence: B)
2. MV surgery is reasonable for asymptomatic patients
with chronic severe MR,* preserved LV
function, and new onset of atrial fibrillation. (Level
of Evidence: C)
3. MV surgery is reasonable for asymptomatic patients
with chronic severe MR,* preserved LV
function, and pulmonary hypertension (pulmonary
artery systolic pressure greater than 50 mm Hg at
rest or greater than 60 mm Hg with exercise).
(Level of Evidence: C)
4. MV surgery is reasonable for patients with chronic
severe MR* due to a primary abnormality of the
mitral apparatus and NYHA functional class III–IV
symptoms and severe LV dysfunction (ejection fraction
less than 0.30 and/or end-systolic dimension
greater than 55 mm) in whom MV repair is highly
likely. (Level of Evidence: C)
Class IIb
MV repair may be considered for patients with
chronic severe secondary MR* due to severe LV
dysfunction (ejection fraction less than 0.30) who
have persistent NYHA functional class III–IV symptoms
despite optimal therapy for heart failure, including
biventricular pacing. (Level of Evidence: C)
Class III
1. MV surgery is not indicated for asymptomatic patients
with MR and preserved LV function (ejection
fraction greater than 0.60 and end-systolic dimension
less than 40 mm) in whom significant doubt about
the feasibility of repair exists. (Level of Evidence: C)
2. Isolated MV surgery is not indicated for patients with
mild or moderate MR. (Level of Evidence: C)
*See Table 1 (7).
The prediction of successful MV repair is important in
timing surgery. This prediction is based on the skill and
experience of the surgeon in performing repair, on the
cause of the MR, and on MV morphology. The skill and
experience of the surgeon are probably the most important
determinants of the eventual success of MV repair.
The number of patients undergoing MV repair for MR
has increased steadily over the past decade in the United
States and Canada in relation to the number undergoing
MV replacement. However, among isolated MV procedures
reported in the STS National Cardiac Database from 1999
to 2000 (359), the frequency of repair was only 35.7% (3027
of a total of 8486 procedures), which suggests that MV
repair is underutilized. Current data indicate that the
frequency of MV repair is increasing yearly (93). The STS
national database also indicates an operative mortality rate of
less than 2% in patients undergoing isolated MV repair in
2004, which compares favorably to the more than 6% operative
mortality rate for patients undergoing isolated MV replacement
(93). In light of the beneficial effect of MV repair on
survival and LV function, cardiologists are strongly encouraged
to refer patients who are candidates for MV repair to surgical
centers experienced in performing MV repair.
Symptomatic Patients With Normal Left Ventricular Function
Patients with symptoms of congestive heart failure despite
normal LV systolic function (ejection fraction greater than
0.60 and end-systolic dimension less than 40 mm) require
surgery. Surgery should be performed in patients with even
mild symptoms and severe MR (Fig. 7), especially if it
appears that MV repair rather than replacement can be
performed.
Asymptomatic and Symptomatic Patients with Left Ventricular
Dysfunction
The timing of surgery for asymptomatic patients is controversial,
but most would now agree that MV surgery is
indicated with the appearance of echocardiographic indicators
of LV dysfunction. These include LV ejection fraction
less than or equal to 0.60 and/or LV end-systolic dimension
greater than or equal to 40 mm (Fig. 7). MV surgery should
also be recommended for symptomatic patients with evidence
of LV systolic dysfunction (ejection fraction less than
or equal to 0.60 and/or end-systolic dimension greater than
or equal to 40 mm).
Determining the surgical candidacy of the symptomatic
patient with MR and far-advanced LV dysfunction is a
common clinical dilemma. The question that often arises is
whether the patient with MR with advanced LV dysfunction
is no longer a candidate for surgery. Although it is
difficult, one must distinguish primary cardiomyopathy with
secondary “functional” MR from primary MR with secondary
myocardial dysfunction. In the latter case, surgery
should still be contemplated if MV repair appears likely
(Fig. 7). In patients with severe LV dysfunction and
significant functional MR, the modification of MV geometry
by an “undersized” annular ring may be beneficial
(360–365), although the impact on outcomes compared
with aggressive medical therapy, including beta blockers and
cardiac resynchronization therapy (338–341), has not been
studied in a prospective randomized trial.
Asymptomatic Patients With Normal Left Ventricular Function
As noted previously, repair of a severely regurgitant valve
may be contemplated in an asymptomatic patient with
severe MR and normal LV function to preserve LV size and
function and prevent the sequelae of chronic severe MR
(324). Although there are no randomized data with which
to recommend this approach to all patients, the committee
recognizes that some experienced centers are moving in this
direction for patients for whom the likelihood of successful
repair is high. Natural history studies indicate uniformly
that asymptomatic patients with severe MR and normal LV
function have a high likelihood of developing symptoms
and/or LV dysfunction that warrants surgery over the course
of 6 to 10 years (313,317,324,325). Two recent studies have
also addressed the risk of sudden death in asymptomatic
patients with severe MR and normal LV function (324,325).
In a long-term retrospective study in which severity ofMRwas
quantified by Doppler echocardiography (324), 198 patients
with an effective orifice area greater than 40 mm2 had a 4%
per year risk of cardiac death during a mean follow-up
period of 2.7 years. However, in the second study of 132
patients followed up prospectively for 5 years, during which
the indications for surgery were symptoms, development of
LV dysfunction (ejection fraction less than 0.60), LV
dilatation (LV end-systolic dimension greater than 45 mm),
atrial fibrillation, or pulmonary hypertension, there was only
1 cardiac death in an asymptomatic patient, but this patient
had refused surgery which was indicated by development of
LV dilatation (325).
MV repair is often recommended in hemodynamically
stable patients with newly acquired severe MR, such as
might occur with ruptured chordae. Surgery is also recommended
in asymptomatic patients with chronic MR with
recent onset of atrial fibrillation in whom there is a high
likelihood of successful valve repair (see below).
Surgery for asymptomatic patients with severe MR and
normal LV function should only be considered if there is a
greater than 90% likelihood of successful valve repair in a
center experienced in this procedure. As noted above, cardiologists
are strongly encouraged to refer patients who are
candidates for MV repair to surgical centers experienced in
performing MV repair.
Atrial Fibrillation
The development of atrial fibrillation is independently
associated with a high risk of cardiac death or heart failure
(366), and preoperative atrial fibrillation is an independent
predictor of reduced long-term survival after MV surgery for
chronic MR (333,366–368). Hence, many clinicians consider
the recent onset of atrial fibrillation to be an indication
in and of itself for surgery, if there is a high likelihood of
valve repair (Fig. 7) (356,369). In patients presenting for
MV operation with chronic atrial fibrillation, a concomitant
Maze procedure may prevent future thromboembolic events
by restoring normal sinus rhythm (370–376). The decision
to proceed with a Maze procedure should be based on the
age and health of the patient, as well as the surgical
expertise, because this procedure may add to the morbidity
of the operation.