%8
1ACC so1 .19. No ,5
Apd11YROss-73
Two-Dimensional and Doppler Echocardiographic Determinants of the
Natural History of Mitral Valve Narrowing ; in Patients With
Rheumatic Mitral Stenosis : Implications for Follow-Up
STEFHEN P. F . GORDON, MB,BS, PAMELA S . DOUGLAS, MD, FACC,
PATRICIA C . COME, MD, FACC, WARREN J . MANNING, MD, FACC
Hosrun,
Massachusetts
Fifty patients with rheumatic mitral stenosis were studied with
serial twmdimeisitital and Doppler echocardiography to deter .
mice the normal history of changes in mural valve area and its
retalton to iransndtra gradients and mil-al valve morphology .
Over the 39-month observatlan period (range 7 m 74 months) the
decline in valve area was 0.09 x 0.21 cmdfyear. In addition, there
were aignilcaat inereasss in total echoeardiagraphie scare (p =
0 .0001), severity of mitral anulas calcification (p
to
0,05) and
severity of ultra) regurgitation (p = 0 .11007). Patients with an
eeborardiographic score wit had a more progressive course .
In addition, patients with a more progressive course (decline in
valve area ?0 .1 cmrhear) had a significantly greater initial mean
gradient (p = 0 .01), peak gradient (p =.007)
0
and total emoar.
diagraphic score 4p = O .000d). Initial valve area did not correlate
The ratural history of rheumatic mitral stenosis has been the
subject of several extensive studies (I-3). These studies
have documented a generally slow, but often variable clinical course, with some patients showing little or no clinical
progression nor lung periods and others manifesting a more
rapid course . In contrast to these clinical studies, little
information is known regarding the temporal changes in
mitral valve gradient or valve area . Such information would
he important because symptomatic deterioration may not
reflect progression in valvuiar stenosis but may be the result
of a coincident event such as the development of atnlal
fibrillation, myocardial failure, pulmonary hypertension or
increasing valvular regurgitation, In addition, the hemodynamic, morphologic and mechanical factors that influence or
predict the rate of stenosis progression have not been
From the Charles A . Dana Research Institute and she Harvard-Thomdlke
laboratory
of she
Beth Israel Hospital, Department of Medicine, Cardiovas .
cular Division, Hem srael Hospital and Harvard Medical School, Boston .
Massadmsetes. Dr. Gordon is supported by a W. A . end M . G . Saw Medical
Research Fellowship from the University of Western Australia . Penh, West.
trot
Aosiralia. Australian Dr. Manning is supported in pan by Physician .
Solent Award P.GCntvs from the National Institute of Aging, Belheea,
Maramd .
Manuscript received July 22 . 1991 : revised manuscripl received October
4,1991, -pre osleber 18. 1991.
Address for rrednh
; : Warren l . Manning. MD. Cardiovascular Division .
Bent Note Hasplml, 330 Braakkne Avenue, Boston . Massaclmseus 02215.
C19112by tie Anseican College of Cardiology
with the rate of stenmis progression. Of 22 patients with an
echocardiographic score <0 and a peak mitral gradient
c10 mm Hg, only I patient (5%) had a more progressive course,
compared with 50% of those with a toted eclrocardiographic score
A and a gradient alO mm Hg.
The rate of mitral valve narrowing in individual patients with
rheumatic mural stenosis is variable. Patients whose valve disease
progresses rapidly are those with a greater mitral valve eehnrardiographie scorn and hither poak and moan lraasniltralgradlautn .
These findings emphasize the importance at nanlnvaslve evalun.
tion of valvular morphology and hemadynamics and have hop1F
cation for the frequency of follow-up mad prognosis in patients
with mural stenosis .
(J Am Cuff Cannot 2992;19:968-73)
identified. Such information is of clinical importance for
determining both the optimal frequency of follow-up in such
patients and the urgency of surgery or percutaneous balloon
valvuloplasty.
The ability to image the valve and subvalvular apparatus
with two-dimensional echocardiography allows for the noninvasive evaluation of mechanical or structural factors, or
both, that might influence the rate of orifice narrowing. This
ability, along with Doppler echocardiography, which permits
repeated noninvasive estimation of hemodynamic factors
including mitral valve area (4) and transmittal pressure
gradient (5), has made possible a more extensive evaluation
of the natural history of mitral stenosis .
The purposes of this study were to determine the nateral
history of changes in mitral valve area and transmittal
gradient in patients with rheumatic mitral sfenessis and to
evaluate structural, mechanical and hemodynamic factors
that might be related to the rate of stenosis progression,
Methods
Study patients. Adult echocardiographic records (u =
6,650), representing all studies performed at our institution
between July 1, 1983 and December 31, 1985, were reviewed. From these, 140 consecutive patients with a rtseu.
matically deformed mural valve and measutrat trarmaritoal
0r715.1097nsess.m
JACC VaL 19, No. 5
Aprl 991-963-73
0AROON as AL.
ECNrrCARDr0RARNV ANa VALVE AREA IN MITRAL STENOSIS
gradient were selected for further study . Of these, 90 patients were excluded because they had no subsequent study
performed before August 31, 1990 or no study performed at
least 6 months after the entry study (n = g0) • had an
intervention (surgical or percutaneous balloon va)vulopiasty) ether previously (n = 1) or before subsequent
echocardiographic study (n = 7) or had technically inade .
quate studies (n = 2), yielding a study group of 50 patients
including 10 torn and 40 women. Their mean age was 56
years (range 23 to 87) . The average interval between entry
and most recent follow-up echocardiographic study was 39
months (range 7 to 74).
Echoeardiographic studies, Two-dimensional imaging
and guided transmittal pulsed Doppler echocardiographic
studies were performed with use of on HP 77030A or
71020AC (Hewlett-Packard) combined imaging/Doppler
echocardiograph equipped with 2 .5-MHz phased array transducers or an ATL MK 690 (Advanced Technology Laboratories) combined imaging/Doppler echocardiograph
equipped with a 3-MHz mechanical transducer . Images were
stored on standard VHS videotape.
Two-dimensional tchocardiographic analysis . Mitral
valve morphology was evaluated with a semiquentitative
scoring method described by Wilkins et al, (6) . This method
assigns a severity grade of 0 to 4 for each of the following
characteristics of the mitral valve! mobility, subvalvular
thickening . leaflet thickening and calcification . A score of 0
represents normality and higher values represent increasing
degrees of severity. A total echocardiographic score (0 to 16)
is derived by summing :ire individual scores . Mitral anulus
calcification was graded as 6 (none), I (mild) . 2 (mo( erate) or
3 (severe). Left atria) dimension was measured in the
parasterrul long-axis view by standard techniques (7). The
echocardiographic studies of all patients were reviewed in
random order by an observer who had no knowledge of
patient data.
Doppler analysis. Doppler recordings of transmittal inflow velocities were recorded from the apical four-chamber
view as previously described (0), Recording= were printed at
a paper speed of 100 mmls and analyzed with an off-line
computer analysis system (Cardiology Workstation, GTl
Freeland Medical Division). Doppler spectra were traced on
a digitizing graphics tablet and analyzed to determine peak
and mean transmittal pressure gradients . Mitral Valve area
was determined by the pressure-half time method (4,9) . A
minimum of five consecutive beats was analyzed in each
patient and the results were averaged . Extent of mitral
regurgitation was assessed by pulsed Doppler recordings and
graded o (none) to 4 (several (10) . Ali Doppler analyses were
performed by a single observer who had no knowledge of
patient outcome and echoeardiographic data.
To assess intro-and iarerohserver vmi0biliry in the Dopplet spectra, 20 patients were randomly selected for repeal
analysis . Interobserver variability was estimated by comparing the values for mean gradient, peak gr_dient and mitral
valve area obtained by two independent observers (S .P .F .G.
%9
Characteristics of 50 Study patients at Entry and at
Follow-Up
Table 1 .
Emry
Neat rate tbeatt'minl
Mean ramminat gradient
67 -- 13
(mm ng)
Peat 95 toAmol grd&em I mm Ngl
Mitral vane once Cur'i
Total Ed0 seers (0-161
Mina]-ake .vehitip(0--' ;
Subvotvulanhidae4e t0-4t
Mitml valve thickening (0-41
Mital valve cakiteation (0-41
Maul anulus ealcdkalion (0-31
4.9
Fallow-Up
(39-)
66 2 14
p Value
NS
14
s .d S 3 .2
103 ! 6 .2
1 .7 S 0.7
5 .4 ! 2 .0
11 .5 ± 5 .8
NS
1 .S x 0.7
9.4 x 2.1
OAOIS
O.OWI
NS
1 .6 1 0%
2.1
±0.9
0-0ml
0.9- 1 .0
3.0 ± In
0.0101
2.2 = 0.9
1.2 _ 1 .1
1
18. o 0.8
2 .5
L0
afoot
0 .5 a 0.9
0.6 x 0.9
LOS
Miael .cVmmion (0-el
1 .4 -1 .3
2 0 =- 1 .5
a0am
Len
5 .0
a 09
5.2 x 1 .1
0.03
51051 d -11i. (cal
W- are mean
OA901
values ± SD . Echo= asaawngnphu .
and .Q
.C Intraobserver variability far the same variables
P
.
was detcruened by comparison of estimations performed by
the same observer an initial evaluation mall >2 months later .
lalerventio es. Computerized hospital records were reviewed to determine those patients who had died or had
undergone mliral valve surgery or percutaneous balloon
mural valvuloplasty between the time of the ir initial study
and the end of August 1990 . Patients who had no documented Initial valve procedures were contacted by telephone to determine if they had undergo" such a procedure
at another institution. If an intervention was performed, the
echocardiographic study immediately before the intervention was used as the follow-up study for analysis . No patient
was lost to follow-up
.
Statistical, methods All results are expressed as mean
values a SD. Comparison of entry data with those at
follow-up was by paired Student t test (two-tailed) . Individual patients were stratified into two groups defined by the
rate of valve area decrease, In the progression group, this
increase was ?0.1 cm°lyear and in the nonprogression group
it was <0 .1 cm=lyear. The unpaired Student t test (twotailed) was used to compare the progression and the nonprogression groups. Multiple group comparisons were by oneway analysis of variance and post hoe testing by the
Newman-Keels method . Least squares linear regression
analysis was used to determine the relation between rate of
progression and the total eclocardiographic score (and its
components) . Significance was defined as a p value s 0 .05.
Results
Group characteristics at entry and fallow-up (Table I).
Over the 39 mouths of follow-up, there was a significant
decrOast is inital valve area (p = 0 .0015), and there were
s:gnineant increases in turai cchnrardiagraphic morphology
score (p = 0 .0001), each of the components 0 the echocardiographic score (all p = 0.9007), severity of miual snubs
calcification Ip= 0 .05), severity ofmitral regurgitation /p~
970
GOtRON ET AL,
ECHOCARUIOGRA!'HY AND VALVE AREA IN MITRAL STENUSIS
7.ACC Vol . 19 . No . 5
April 1992:908-77
1.0-
I
0 .g'
~
u^
0b'
GA-
M
0201
00
U
-02
o
DA
0-3
(n-It)
47
In-31)
0
0-12
10
Total Echo Score
Figure 1 . Comparison of total echocardiographic (Echo) score and
rate of initial valve narrowing in 50 patients . 'p < 0,05 versus
echocardiogmphic scores 0 to 3 and 4 to 7 ; n r mtmber of patients
in each group.
0.0007) and left a'rial dimension (p = 0.03). There were no
significant differences in mean Iransmitrat gradient, peak
transmittal gradient or heart rate at rest,
Change in mitral valve area. The mean rate of decline in
mitral valve area was 0.09 ± 0.21 cm'lyear (p = 0 .0015).
Analysis of variables that might be associated with the rate
of stenosis demonstrated a significant difference in the rate
of progression between patients with a total entry echocardiographic score <8 (0,0 *_ 0 .1 em 2 lyear) and patients with a
score >_8 (0 .3 ± 0 .3 c0 year) (p < 0 .05) (Fig . I). There was
no significant difference in the rate of valve area decrease
between men and women, patients with sinus rhythm (n =
32) and atria[ fibrillation (n = 18), patients with increased
(>4 cm) and normal left atria) dimension or among patients
with mild (valve area >2 cm'), moderate (valve area .4
1 to
2 cm') or moderately severe (valve area . <1 .4 cm') mitral
stettosis at study entry .
The interobserver variabilities were minimal with a correlation coefficient of r = 0 .96 and SEE = .19 mm Hg for
comparison of peak gradient (range of peak gradients : 4 to
29 mm Hg); r = 0.96 and SEE = 0.7 mm Hg for mean
gradient (range of mean gradients 1 .8 to 9 mm Hg), and r =
0.93 and SEE = 0 .2 cm' for mitral valve area (range of valve
areas 0.6 to 3.1 cm2), Intraobserver variabilities were also
small with a correlation coefficient of r = 0-98 and SEE _
.4 mm Hg for peak gradient (range 4 to 28 .7 mm Hg), r =
1
0.95 and SEE = 0 .7 mm Hg for mean gradient (range 1 .5 to
15 .2 mm Hg) and r = 296 and SEE = 0 .2 cm'- for valve area
(range 0 .8 to 3 .1 cm').
Progressive and nvaprogressse groups . Examination of
the individual data (Fig . 2) demonstrated two subgroups of
patients, are with relatively rapid progression of declire in
valve area and a second with little or no change in valve area
over the follow-up period . To better define the characteris-
20
30
40
6o
Ranked Patient Order
(n.al
Figure 2. Individual (patient rank order) rates of moral valve
narrowing for all 3D study patients . Patients were stratified in the
ptnoression (triangles, n ' 16)or the nonprogression (circles, a =34)
group
the basis of valve narrowing a0 .1 cm'lyear or
<0 .1 em'tycar, respectively.
ties associated with more rapid progression, study patients
were stratified into two groups defined by the rate of valve
area decrease for each patient being greater (progression) or
less (nonprogression) than 01 cm 2lyear, The progression
group comprised 16 patients (32% of the study group), and
the nonprogressive group included 34 patients . The mean
rate of valve area decrease in the progression group was 0 .3
0.2 cm 2lyear ; in the nonprogression group, valve area did
not change (0 ± 0.l cm2)year) .
The chamcterisries at study entry were compared between the progressive and nonprogressive groups (table 2).
The progression group had a greater mean transmittal gra-
Wit, 2. Entry Characteristics of Caoups With Progression
and Nonprogression
Proerssion Nonprogression
(n = 16)
(n = 34)
p Value
Hale ofvalvenanowtm(cm"N)
Oar lyn
%Women
Hein rate (ficaw'mim
Wall salve area (am e)
Mean Itatumival gndknt
term till
Peak transtdiral
lair Hg)
geadient
0.7±0.2
58 ! 18
010.1
94
72 ± 10
1 .7 1-0.6
6.7 ! 4 .0
17
79
65 *- 14
.8
16T0
4.1 ± 2 .7
NS
NS
Y5
NS
0.01
Et
13.7 a 7 .7
R.7 ± 4 .7
0,007
Total Echo scare (9-I61
Milm I valve mabillw (0-4)
Suh'oivdecehkkening(0-4)
Mibm1 valve thickening (0-4)
Mural valve cakificetian (6-4)
MItmI anuius ealeincalion (0-3)
Mam1 regurgitation (0-4)
7 .8 2 2 .9
1 .9 m 0.8
1 .2 a: 1 .1
2 .6 0 0A
20 a 1 .2
04 a 0.9
5.0 ± 2 .3
0 .4998
0 .02
N5
003
Left trAil dimension Jr .)
4,7
Values are mean values a
SD .
1,4 ^- :
D.8
1.4 n 0.7
0.8 s 1 .0
2.0 ! 0 .8
0.8 *- 0.9
.1 ! 0.9
0
1.4 0 1 .3
5.1 a 0.9
Abbreviations as in Table
I.
0.0004
NS
NS
NS
MACC Vol . 19 . No. 5
AP11 1992:968-13
GORDON ET AL.
LCHUrARDIaORAPHY AND VALVE AREA IN MITRAL STI :RVS15
12
la
e-
q
m
D
O
0
0 0
2
n
o
mo
D Da
a
20
to
Peak Gradiew. (mm He)
30
Flip me 3, lndioidual entry study echeearutagraphic (Echo) score
and peak tree,milml 8radieat rot all 50 study patients . Only I (5%)
of 22 patients with an eehncardiogaphic score c8 and a peak
transmittal gradient .10
v mm Hg was in the progression group
(Wangls) wmpared with 6 180%1 of the IO patients wilh an
echocardiographic scare >8 and a peak gradient >t9 mm He.
Circles = patients in the nonprogression group .
dient (p = 0.01) . peak transmittal valve gradient (p = 0 .007).
and total eehocardiographic score (p - 0.0008). The groups
did not differ in age, gender, heart rate at rest. I hyihm, initial
mitral valve area, severity of mitral anuius calcification,
severity of mitral regurgitation or left atrial size . Mean
follow-up time was longer in the nonprogression than in the
progression group (44 vs . 31 months, p = 0.03) .
Each of the significant variables was examined to determine if a threshold existed that might be clinically useful in
identifying patients at increased risk for having a progressive
course. Of 36 patients with an echocardiographic morphology score <8, only 5 (14%) were in the progression group
compared with 11(79%) of 14 patients with a score all (Fig .
3) . Of 28 patients with a peak gradient <10 mm Hg, only 4
(14%) had a progressive course. Only t (5%) of 22 patients
with a total eehocardiographic score <8 and a peak gradient
<10 mm Hg, only I had a progressive course (Fig . 3).
Discussion
. The classic natural history studies of
Previous shift
Rowe et al . (0, Oleson (2) and Grant (3) have shown that
while the overall rate of clinical progression in patients with
rheumatic mitral stenosis is slow, the rate of progression
varies widely among patients. In the study of Rowe et al . (1)
of 250 patients with mitral stenosis, at 10-year follow-up 40%
had not changed symptom status, 40% had died and 20% had
shown progression, Of the patients who were initially
asymptomatic, 59% remained without symptoms at 10 years
compared with only 24% at 20 years . Similarly, Cram (3), in
a study of 238 British servicemen with mitral stenosis, noted
that at 10-year follow-up . 33% had died. 33% had no change
971
in symptoms and 33% had shown progression . Unfortu. these carly studies lacked the hemodynamie data that
nately
would ncrmit determination of whether rapid symptomatic
deterioration reflects a faster rate of valvular stenosis or is
the result of another cumptication such as atrial fibrillation,
myocardial failure, pu'monary hypertension or valvular incompetence.
Orbits et al . (11) studied serial hemodynamic data from 42
patients with mitral stenusis who had two or more cardiac
catheterizatiens over a period of up to 10 years. Sixty-seven
percent of the patients showed evidence of progression, with
a mean rate of valve area loss in this group of 032 cmzlyear
over a mean follow-up period of 2 .6 years, whereas 33%
showed no change in valve area over a mean follow-up
period of 3 .7 years. Patients who showed progression of
valve area decline were more likely to show symptomatic
deterioration during the follow-up period . This study was
limited by the face that an observationallretrospectivc study
of patients having a second catheterization will be biased
toward patients with more progressive disease . Thus, the
true prevalence of patients with progressive disease may
have been overestimated in this study.
Leurcrtegger et al . (12) studied 13 patients with mitral
stenosis in New York Heart Association llmetional class I or
I1 with M-mode echocardiograms separated by a mean of 37
months. Examining EF slope and mitral valve closure index,
they identified a subgroup comprising 23% of the study
group who manifested greater progression . The substantial
limitations of the EF slope and other M-mode measurements
in quantifying severity of mitral stenosis have since been
defined 111), although their use in monitoring changes in a
single patient may still be valid (14).
Present Tidings By utilizing noninvasive cardiac imaging and Doppler estimates of mitral valve area and iransmitml gradients, our study avoids many of the limitations of
these previous studies and adds important additional data
regarding mitral valve morphology and valvular regurgitation. The ability to describe mitral valve morphology with
two-dimcnsioaal echocardiography has allowed for a mere
thorough investigation of the possible determinants of more
rapidly progressive stenosis. We confirm the previously
described variability in the rate of stenosis progression.
More than 67% ofthe patients in our series showed minima)
or no change in valve area over several years, whereas
almost 33% showed a more malignant course . The rate of
change in mitral valve area observed in Our progression
group is very similar to that observed in the comparable
group of Dubin et al . (11), who utilized catheterizationderived valve areas.
An important finding in our study was that the initial
mitral valve area at study entry did not help identify patients
who exhibited more rapid progression in valve area decline .
Our analysis, however, does identify several other important
echocardiographic characteristics at the entry study that are
associated with an increased rate of mitral valve stenosis .
Patients with higher peak and mean transmital gradients and
972
GORDON FT A1 . .
ECNOCARDIOORAPtIY AND VALVE AREA IN MITAAL STr:NU5IS
those with higher echocardiographic scores for mitral valve
mobility, thickening, calcification and total morphology
were more likely to exhibit a more progressive course than
were patients with low gradients and low echocardiographic
scores . A total echocardiographic score <8 mm Hg or a peak
Iransmitral gradient <i0 mm Hg, ur boo,, represent levels
that identify patients with a very low incidence of progressive stenosis . Conversely, patients with a score a8 are much
more likely to exhibit progression and they represent a group
in whom closer follow-up should be considered,
Pathogenesis of progression. Although there is still debate
about whether the progressive changes observed in mitral
stenosis might result from a continuous lowgrade subclinical
rheumatic process, most authorities now view the progressive anatomic changes in the mitral valve to be the response
of valvular tissue to the stress of chronic turbulent flow
through a deformed valve (15) . Variations in the degree of
initial valvular deformity may be a result of differences in the
severity of the initial infection, streptococcal virulence or
the number of attacks of rheumatic fever. The greater the
morphologic deformity, the greater the turbulence, leading
to greater tirrue stresses, which result in further thickening,
calcification and cotnmissural fusion . This is also consistent
with the concept of hemodynnmie forces acting to influence
the rate of stenosis, with greater gradients causing greater
tissue stresses and thus a greater proliferative and calcific
reaction. Such a hypothesis is in keeping with our data
demonstrating that valves exhibiting greater morphologic
deformity, and thus a higher echocardiographic score, shea greater tendency to more rapid stenosis .
Comparison with postvalvotwtiy studies. If mitral valve
morphology and gradient influence the rate at which stenosis
progresses in the absence of an intervention, then the same
factors may influence the incidence and timing of restenosis
after surgical valvotomy or percutaneous balloon valvuloplmty. The reported incidence of restenosis after open or
closed surgical valvotomy has varied considerably among
diderent studies, with estimates varying between 2% and
60% (16) . Several of these studies have documented increased valvular calcification as a risk factor for late deterioration (17,18). Initial success of the valvatomy and the
subsequent course do not correlate closely, suggesting that
factors other than the absolute valve area determine the rate
at which symptoms return (17). In an extensive review and
follow-up of 339 patients after open or closed commissurotomy, Hickey et al . (18) documented a need for mitral valve
replacement at 10 years in 22% of patients and a need for
valve replacement at 20 years in 53% . Risk factors for
subsequent valve replacement were the severity of stenosis
before commissurotomy, the degree of mitral leaflet coleiflcation and immobility and the degree of mitral regurgitation
after commissurotomyFew studies, however, have been able to determine
whether true restenosis or an inadequate primary result has
been the cause of late symptomatic deterioration as surgical
results arc rarely assessed hemodyuamically . However.
JACC Vol . 19, en, 5
April 1992 :955-73
fliggs et al . (19), by comparing a routine early postoperative
cardiac catheterization with subsequent data, documented
true restenosis in 5 of 45 patients who returned with recurrent symptoms over a meali follow-up period of 6.5 years . In
another study, Heger et a! . (201 followed up 18 patients who
had en early postoperative catheterization after successful
commissurotomy with either echocardiography or repeat
cardiac catheterization at a mean of 12 .2 years. Significant
restenosis was found in five patients (28%). As in our study,
neither age nor gender nor initial valve area was predictive of
later restenosis.
Factors influencing restenosis following pereutaneom halloan mitral vnlvuloplwty . These factors have been the subject ofmore intense scrutiny. Uncles et al . (21) reportedthe
outcome of 100 patients followed up an average of 13 mouths
after percutaneous balloon valvuloplasty . Mural valve morphology was assessed by the same echocardiographically
based scoring method utilized in our study . Patients with a
low total echocardiographic score (tell) had only a 4%
incidence of restenosis documented, whereas those with a
score >8 had a 7040 incidence . The individual components of
this score were not examined for their relation to later
restenosis. Although patients with a higher score were less
likely to have a good immediate hemadynamic result, multiple stepwise regression analysis identified the echocardiographic score as the single most importune factor predictive
of restenosis, whereas the mitral valve area immediately
after valvuloplasty was not predictive of restenosis by either
univariate or stepwise multiple regression analysis . These
results are consistent with those of the present study and
suggest that the same pathogenic mechanisms may be operating. Patients who achieve a good long-term result after
balloon mitral valvuloplasty may do so as a result of already
belonging to a slow progression subgroup determined, al
least in part, by their valve morphology . Such observations
held significant implications for the selection of patients
most likely to benefit from mitral valvuloplasry and the
timing or valvuloplasty and follow-up study .
Limitations . Several potential biases are inherent in the
present study . Retrospective studies of untreated natural
history tend to select patients with less severe disease, as the
more severely affected patients are more likely to have had
an intervention before follow-up study . Many of our patients
did have mild mitral stenosis, but the number of patients
with a small valve area at entry in both the progression and
nonprogression groups suggests a reasonably equal distribution of patients with moderately severe stenosis in both
groups. Patients with a more progressive clinical course
might be expected to have more frequent echocardiographic .
follow-up studies and thug. be overrepresented . This does not
appear to be the situation far oo' -idy because the majority
of patients were in the nonprogression group . We also
assumed a linear progression between entry and final echocardiographic studies . Tins seems reasonable given the
similar progression rates in patients with mild and more
severe mitral stenosis .
JArr Vol . 19.N ..5
Ap.. 1992 WM-71
GORINN Ei AL.
RCHVCARD7o4R,1Pev AND V.mL1'E AREA IN MITRAL STh91151S
Some patients showed an apparent increase in valve area
over the follow-up period . The magnitude of this apparent
increase, however. was small in all but one patient and
within the range of variation in the IBeasuTement technique
as determined from our inrraohserver error analysis . The
milral valve echocardiographic score 111etnod used in this
study is a subjective grading and is semiquantitative in
nature (22) . However, it has been successfully applied to
studies of outcome after percutaneous balloon vaivuloplasty. The method has also been validated against postmortem specimens of rheumatic milral valves (23) .
Clinical ii ig4icatious . In addition to furthering our understanding of the natural history of rheumatic mural slenosis,
the results of this study are of importance in the clinical
management of such patients and in understanding the
mechanism of resienosis after surgical or balloon valvuluplasly. The rate of progression of milral stenosis in individual patients is quite variable . Health care resourceswould be
best utilized by individualizing patient follow-up based on
the likelihood of progression of stenosis- Our data suggest
that patients with a low echocardiographic score and a law
transmitral gradient have a low rate of valve area narrowing
and may need less frequent echocardiugraphic follow-upMost important, this study stresses the relation between
valvular morphology as assessed by echocardiography and
the clinical course ofpatients with mitral stenosis . The value
of morphologic assessment in predicting the outcome after
surgical valvotomy or balloon valvuloplasty has already
been demonstrated. Our study extends the utility of this
index to that of the natural history of progression of valve
Cterteale .
We art Fateful fo, Ike leehniool as,puoece of Manlyn S . Rile. . RDCS and
Lisa V, Cad, RDCB.
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