From Massachusetts General Hospital, Harvard Medical School, Boston,
Mass.
Correspondence to Igor F. Palacios, MD, Cardiac Catheterization Laboratory and Interventional Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114. E-Mail palacios{at}olorin.mgh.harvard.edu
Percutaneous mitral balloon valvotomy
(PMV) has been accepted as an alternative to surgical mitral
commissurotomy in the treatment of patients with
symptomatic rheumatic mitral stenosis. Previous
studies have demonstrated that PMV produces good immediate and
long-term follow-up results in a selected group of patients with mitral
stenosis.1 2 3 4
Hemodynamic and clinical improvement is achieved in the
majority of patients with rheumatic mitral stenosis. PMV
resulted in a significant decrease in mitral gradient and an increase
in mitral valve area with minimal morbidity and mortality. The majority
of patients have a marked clinical improvement, and the
hemodynamic and clinical improvement produced by PMV
persist at long-term follow-up.2 3 4 On the other hand,
surgical mitral commissurotomy has been used successfully for many
years to treat patients with mitral stenosis. The results of
closed or open surgical mitral commissurotomy have demonstrated
favorable immediate and long-term hemodynamic and
symptomatic improvement in selected patients with rheumatic
mitral stenosis.
Interpretation of long-term clinical follow-up of patients
undergoing percutaneous mitral balloon valvuloplasty as
well as their comparison with surgical commissurotomy series are
confounded by heterogeneity in the patient population.
Only few randomized studies have compared the results of PMV with those
of surgical commissurotomy. In this issue of the journal, Farhat et
al5 reported the results of a randomized trial designed to
compare the immediate and long-term results of double-balloon PMV
versus those of open and closed surgical mitral commissurotomy in a
cohort of patients with severe rheumatic mitral stenosis. These
patients were, from the clinical and morphological point of view,
optimal candidates for both PMV and surgical commissurotomy (closed or
open) procedures as demonstrated by a mean age of <30 years, absence
of mitral valve calcification on fluoroscopy and two-dimensional
echocardiography, and an
echocardiographic score
Patient selection is fundamental in predicting immediate outcome and
follow-up results of PMV and surgical commissurotomy procedures. In
addition to clinical examination, echocardiographic
evaluation of the mitral valve and fluoroscopic screening for
valvular calcification are the most important steps in patient
selection for successful outcome. The evaluation of candidates for PMV
requires a precise evaluation of both valve morphology and function for
preprocedure decision making and follow-up of the patients.
Two-dimensional echocardiography is currently the
most widely used noninvasive technique for the evaluation of the
morphological characteristics of the mitral valve, subvalvular
apparatus, and the valve annular size. An important
predictor of the immediate and long-term results of PMV is a
morphological echocardiographic score developed at the
Massachusetts General Hospital.6 In this score, leaflet
rigidity, leaflet thickening, valvular calcification, and
subvalvular disease are each scored from 1+ to 4+, yielding a
maximum total echocardiographic score of 16. A higher
score would represent a heavily calcified, thickened, and
immobile valve with extensive thickening and calcification of the
subvalvular apparatus. Among the four components of
the echocardiographic score, valve leaflet thickening
and subvalvular disease correlate the best with the increase in
mitral valve area produced by PMV. An inverse relation between the
increase in mitral valve area produced by PMV and the
echocardiographic score has been
demonstrated.3 4 5 6 A similar relation exists between the
echocardiographic score and the percentage of patients
obtaining a good result from PMV defined as a post-PMV mitral valve
area of
PMV complications are low and occur more frequently in patients
with echocardiographic scores >8. Mortality and
morbidity with PMV is low and similar to surgical commissurotomy. In
the series from the Massachusetts General Hospital of 734 patients
undergoing PMV, there was a 0.6% mortality and a 1.3% incidence of
thromboembolic episodes and stroke. Pericardial tamponade occurred in
0.8% of cases in this series. Tamponade occurs more frequently from
transseptal catheterization and rarely from
ventricular perforation. Severe mitral
regurgitation (4+) occurred in 3% of the patients,
with some of them requiring in-hospital mitral valve replacement. An
increase in mitral regurgitation
The reliability of the echocardiographic score for
predicting results of PMV is not optimal because results of the PMV are
also related to other factors such as the presence of fluoroscopic
mitral valve calcification, the age and sex of the patient, the
presence of atrial fibrillation, pre-PMV mitral
regurgitation and pulmonary hypertension, a
history of previous surgical commissurotomy, the technique of PMV
(double balloon versus Inoue), the severity of mitral stenosis
before PMV, and the ratio of EBDA/BSA.3
The presence of fluoroscopic visible calcification on the mitral valve
is another important factor that influences the success of
PMV.8 Patients with heavily calcified mitral valves have a
poorer immediate outcome, as reflected in a smaller post-PMV mitral
valve area. The long-term survival and event-free survival are
significantly lower for patients with calcified mitral valves than for
those with uncalcified valves. Furthermore, the survival and event-free
survival curves become worse as the severity of valvular
calcification becomes more severe. These findings are in agreement with
several follow-up studies of surgical commissurotomy, which
demonstrated that patients with calcified mitral valves had a
significantly poorer survival compared with those patients with
uncalcified valves.
Age is another important factor determining the immediate and
long-term outcomes of PMV.9 We have previously reported a
46% success rate in patients
The presence of atrial fibrillation is adversely related to the outcome
of PMV. Patients in atrial fibrillation have clinical and morphological
characteristics associated with inferior results after PMV
such as older age, higher incidence of
echocardiographic scores >8, and history of previous
surgical commissurotomy. In patients with atrial fibrillation, PMV
resulted in inferior immediate and long-term outcomes, as
reflected in a smaller post-PMV mitral valve area and a lower
event-free survival at long-term follow-up. In this group of patients
with atrial fibrillation, post-PMV mitral regurgitation
grade
PMV also has been shown to be a safe procedure in patients with
previous surgical mitral commissurotomy.10 Although a good
immediate outcome is frequently achieved in these patients, event-free
survival is greater among those patients without previous
commissurotomy. However, when patients are carefully selected through
the use of an echocardiographic score
There is no unique technique of percutaneous mitral
balloon valvuloplasty. Most of the techniques of PMV require
transseptal left heart catheterization and use of the
antegrade approach. Antegrade PMV is more frequently accomplished with
either the double-balloon or the Inoue techniques. There is controversy
as to whether the double-balloon technique versus the Inoue technique
of PMV provides superior immediate and long-term results. Compared with
the Inoue technique, the double-balloon technique results in larger
mitral valve area and lesser degree of severe mitral
regurgitation after PMV, particularly in patients with
echocardiographic scores
Comparison between PMV and surgical commissurotomy techniques is
difficult in view of differences in patient clinical and mitral valve
morphology characteristics among different series. Most surgical series
have involved a younger population with optimal mitral valve morphology
(pliable with no calcification and no evidence of subvalvular
disease). Differences in age and valve morphology may account for the
lower survival and event-free survival of PMV series from United States
and Europe. For example, in the series from the Massachusetts General
Hospital, 497 patients with echocardiographic scores
A larger number of patients with higher
echocardiographic scores and mitral valve calcification
may account for the 5-year 76% survival and a 51% combined event-free
survival reported by Cohen et al11 in a group of 146
patients undergoing PMV. Furthermore, 39% of the patients in this
later series were considered to be at high surgical risk because of the
presence of important coexisting conditions or advanced age.
On the contrary, survival and event-free survival after PMV in optimal
patients for this technique appear to be similar to those reported
after surgical mitral commissurotomy. In the series from the
Massachusetts General Hospital, 202 optimal candidates defined as
patients <65 years old, in normal sinus rhythm, with
echocardiographic scores
In patients with optimal mitral valve morphology, surgical mitral
commissurotomy has favorable long-term hemodynamic and
symptomatic improvement. Similarly to PMV, patients with
advanced age, calcified mitral valves, and those with atrial
fibrillation had poorer survival and event-free survival after surgical
commissurotomy. Several studies have compared the immediate and early
follow-up results of PMV versus closed surgical commissurotomy in
optimal patients for these techniques. The results of these studies
have been controversial, showing either superior outcome from
PMV12 13 or no significant differences between both
techniques.14 15 16 Patel et al12 randomized 45
patients with mitral stenosis and optimal mitral valve
morphology to closed surgical commissurotomy and to PMV. He
demonstrated a larger increase in mitral valve area with PMV (2.1±0.7
versus 1.3±0.3 cm2). Shrivastava et al13
compared the results of single-balloon PMV, double-balloon PMV, and
closed surgical commissurotomy in three groups of 20 patients each. The
mitral valve area after intervention was larger for the double-balloon
technique of PMV. Postintervention valve areas were 1.9±0.8, 1.5±0.4,
and 1.5±0.5 cm2 for the double-balloon, the
single-balloon, and the closed surgical commissurotomy techniques,
respectively. On the other hand, Arora et al14 randomized
200 patients with a mean age of 19±7 years and mitral stenosis
with optimal mitral valve morphology to PMV and to closed mitral
commissurotomy. Both procedures resulted in similar postintervention
mitral valve areas (2.39±0.9 versus 2.2±0.9 cm2 for the
PMV and the mitral commissurotomy groups, respectively) and no
significant differences in event-free survival at a mean follow-up
period of 22±6 months. Restenosis documented by
echocardiography was low in both groups, 5% in the
PMV group and 4% in the closed commissurotomy group. Turi et
al15 randomized 40 patients with severe mitral
stenosis to PMV and to closed surgical commissurotomy. The
postintervention mitral valve areas at 1 week (1.6±0.6 versus 1.6±0.7
cm2) and 8 months (1.6±0.6 versus 1.8±0.6
cm2) after the procedures were similar in both groups.
Reyes et al16 randomized 60 patients with severe mitral
stenosis and favorable valvular anatomy to PMV
and to surgical commissurotomy. They reported no significant
differences in immediate outcome, complications, and 3.5-year follow-up
between both groups of patients. Improvement was maintained in both
groups, but mitral valve areas at follow-up were larger in the PMV
group (2.4±0.6 versus 1.8±0.4 cm2).
Although these initial randomized trials results of PMV versus surgical
commissurotomy are encouraging and favor PMV for the treatment of
patients with rheumatic mitral stenosis with suitable mitral
valve anatomy, there is a need for long-term follow-up studies
to define more precisely the role of PMV in these patients. The report
of Farhat et al5 provides this long-term follow-up in a
cohort of optimal candidates for PMV and clearly establishes the role
of PMV in the treatment of these patients. The immediate and long-term
results of PMV in these patients are similar to those obtained with
open surgical commissurotomy and significantly superior to those
obtained with closed surgical commissurotomy. The postintervention
mitral valve areas achieved with PMV were similar to the one obtained
after open surgical commissurotomy (2.5±0.5 versus 2.2±0.4
cm2) but larger than those obtained after closed
commissurotomy. These initial changes resulted in an excellent
long-term follow-up in the group of patients treated with PMV, which
was comparable with the open commissurotomy group and superior to the
closed commissurotomy group. Because open commissurotomy is associated
with thoracotomy, need for cardiopulmonary bypass, higher cost,
longer length of hospital stay, and a longer period of convalescence,
PMV should be the procedure of choice for the treatment of these
patients.
The inferior results of closed mitral commissurotomy
presented by Farhat et al5 are in disagreement
with previous studies showing no significant differences in immediate
and follow-up results between PMV and closed surgical mitral
commissurotomy.14 15 16 However, as pointed out by Farhat,
the increase in mitral valve area after closed commissurotomy is not
uniform and often unsatisfactory. Regardless of this controversy, the
report of Farhat et al provides further support to the concept that PMV
should be the procedure of choice for the treatment of patients with
rheumatic mitral stenosis who are from the clinical and
morphological point of view optimal candidates for PMV.
Footnotes
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
References
© 1998 American Heart Association, Inc.
Editorials
Farewell to Surgical Mitral Commissurotomy for Many Patients
Key Words: : Editorials • mitral valve • surgery • balloon
8 in all patients. Their
results demonstrate that the immediate and long-term results of PMV are
comparable to those of open mitral commissurotomy and superior to those
of closed commissurotomy. The hemodynamic improvement,
in-hospital complications, long-term restenosis rate, and need
for reintervention were superior for the patients treated with either
PMV or open commissurotomy than for those treated with closed
commissurotomy. 
1.5 cm2, without 2 grade increase in the
severity of mitral regurgitation and without
left-to-right shunt of 1.5:1 across the interatrial septum.
Patients with lower echocardiographic scores have a
higher likelihood of having a good outcome from PMV with minimal
complications and a hemodynamic and clinical
improvement that persist at long-term follow-up.3
Long-term follow-up studies have shown that patients with
echocardiographic scores 8 have a significantly
greater survival and freedom from combined events (death, mitral valve
replacement, redo PMV, and New York Heart Association class III or IV)
than those patients with echocardiographic scores
>8.3 2 grades occurred in
12.5% of patients. It is well tolerated in most patients, and more
than half of them have less mitral regurgitation at
follow-up cardiac catheterization. Effective balloon
dilating area normalized by body surface area (EBDA/BSA) is the only
predictor of increased mitral regurgitation with PMV.
More recently, an echocardiographic score that predicts
post-PMV mitral regurgitation has been
proposed.7 This score evaluates uneven distribution of
thickness in the anterior and the posterior leaflets, degree of
commissural disease, and subvalvular disease, with each
component graded 0 to 4. The total mitrial regurgitation echo score is
significantly higher in patients who develop severe mitral
regurgitation. PMV is associated with a 15% incidence
of left-to-right shunt immediately after the procedure. The
pulmonary-to-systemic flow ratio is <1.5:1 in the majority
of the patients. The incidence of left-to-right shunt through the
atrial communication is greater in patients with
echocardiographic scores >8. 65 years. In this population,
independent predictors of success included a lower
echocardiographic score, lower pre-PMV NYHA functional
class, and a larger pre-PMV mitral valve area. A low
echocardiographic score was the independent predictor
of survival, and the lack of mitral valve calcification was the
strongest predictor of event-free survival. 3, echocardiographic score >8, and pre-PMV
NYHA class IV are independent predictors of combined events at
follow-up. 8, the
immediate outcome and long-term follow-up results are excellent and
similar to those seen in patients without a history of previous
surgical commissurotomy. 8. However, despite the
difference in immediate outcome between both techniques, there are no
significant differences in survival, event-free survival, and
restenosis at long-term clinical follow-up. 8 and a mean age of 51±14 years have an 85% survival and a 45%
event-free survival at 8-year follow-up. In contrast, 237 patients with
echocardiographic scores >8 and a mean age of 63±14
years have a 55% 8-year survival, and only 20% of them were free of
combined events at 8-year follow-up. 8, without mitral valve
calcification, and with pre-PMV mitral regurgitation
1 grade had an excellent immediate and long-term outcome as reflected
in a 97% survival and 76% event-free survival at a median follow-up
of 61 months.
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