Influence of mitral valve morphology on mitral balloon commissurotomy: Immediate and six-month results from the NHLBI Balloon Valvuloplasty Registry Echocardiographic data were analyzed in 555 patients undergoing mitral balloon commissurotomy (MBC). Patients were enrolled in the National Heart, Lung, and Blood Institute Balloon Valvuloplasty Registry from 24 centers. There were 456 women and 99 men with a mean age of 54 years. Before MBC the two-dimensional echocardiographic variables of mitral valve thickness, mobility, calcification, and subvalvular disease were evaluated and assigned scores of 1 to 4. The mitral valve morphology score was related to mitral valve area (WA) measured after MBC by cardiac catheterization. The leaflet mobility score was related to the immediate post-MBC WA: 2.2 f 0.6 cm* for grade 1, 1.9 + 0.7 cm* for grade 2, 1.7 f 0.7 cm* for grade 3, and 1.9 + 0.9 cm* for grade 4 (p < 0.001). Results of the MVA after MBC showed a similiar relationship for each echocardiographic variable. The total morphology score (sum of the four variables) showed a weak relationship to MVA immediately after MBC (f = -0.24), which was persistent at 6 months after MBC (r = -0.25). Multiple regression analysis showed that the MVA after MBC is predicted by pre-MBC MVA (p < O.OOl), left atrial size (p = O.Ol), balloon diameter (p = 0.02), cardiac output (p = 0.004), and leaflet mobility (p = 0.01). The R* of the model was 0.31 (p < 0.001). Total morphology score, leaflet thickness, calcification, and subvalvular disease were not important univariate or multivariate predictors of the results of MBC. These data suggest that although mitral valve morphology, particularly leaflet mobility, relates to MVA after MBC, other variables such as the severity and duration of disease are also important and are influenced by the larger balloon sizes used in the procedure. Mitral valve morphology should not be used alone in the selection of patients for MBC. (AM HEART J 1992;124:657.)

Cheryl L. Reid, MD, Catherine M. Otto, MD, Kathryn B. Davis, PhD, Arthur Labovitz, MD, Katherine B. Kisslo, RDMS, Charles R. McKay, NHLBI-BVR Investigators* Orange, Calif.

The standard treatment for patients with symptomatic mitral stenosis has been surgical intervention with either a closed or open mitral commissurotomy. Since it was first described by Inoue et a1.l in 1984, balloon commissurotomy has played an increasing role in the treatment of such patients. Early results of balloon commissurotomy have shown increases in the mitral valve area (MVA) and relief of symptoms

From

UC1

Supported and Blood Received Reprint Center, *Registry 4/1/3928Q

Medical

Center.

by the Balloon Valvuloplasty Institute contract NOl-HV-78100. for publication

Jan.

29, 1992;

Registry, accepted

requests: Cheryl L. Reid, MD, Division 101 The City Dr., Orange, CA 92668. participants

are listed

in the Appendix.

National March

of Cardiology,

Heart,

Lung,

10, 1992. UC1 Medical

MD, and the

in patients with severe mitral stenosis.2-6 Previous experience with surgical commissurotomy has shown that the results of the procedure are influenced by the morphology of the mitral valve.7-g Preliminary reports from experienced centers have suggested that this is also true for mitral balloon commissurotomy (MBC). lo, l1 Echocardiography has been the primary method used in analysis of mitral valve morphology before either surgical commissurotomy or MBC.12-14 In response to the initial favorable results of MBC, the National Heart, Lung, and Blood Institute initiated a registry of patients undergoing the procedure in the United States and Canada. The purpose of this report is to describe the relationship of clinical, procedural, and two-dimensional echocardiographic analysis of mitral valve morphology to the immediate hemodynamic and 6-month echocardiographic results of these patients undergoing MBC. 657

658

Reid et al.

American

Table I. Mitral valve morphology echocardiography

by two-dimensional

Morphology

Score

Mobility Highly mobile valve with leaflet tips only restricted Leaflet mid and base portions have normal mobility Valve continues to move forward in diastole, mainly from the base No or minimal forward movement of the leaflets in diastole Leaflet thickening Leaflets near normal in thickness (4 to 5 mm) Mid leaflets normal, marked thickening of margins (5 to 8 mm) Thickening extending through the entire leaflet (5 to 8 mm) Marked thickening of all 1eaAet tissue (>8

1 2 3 4

1 2 3

1 2 3 4

that included

6-month

3 4

-

METHODS The entry of patients into the registry beganon November 1,1987 and wascompleted on October 31,1989. Twenty-four centers prospectively entered all patients aged 18 yearsor moreundergoingMBC at their institution. A MBC procedurewasconsideredto be initiated when the skin was entered for an intended balloon commissurotomy in patients with a previous diagnostic cardiac catheterization demonstrating significant stenosis.If the MBC was performed in the sameprocedure as the diagnostic catheterization, the MBC was consideredto be initiated when the balloon catheters entered the patient. All patients gave informed consent to a protocol approved by an institutional review board at eachparticipating center. The registry was designedasa multicenter cooperative study and not a controlled trial; therefore no attempt was made to influence patient selectionor subsequentclinical managementat the participating centers. For each patient, baselinedata forms were submitted to

history,

(2) functional

follow-up

visits, and (7) complications

during

the

procedure. The echocardiographic findings were interpreted by the individually participating centers. Each study site had a designated principal echocardiographer listed in the Appendix. Prospective data for the registry were forwarded to the coordinating center at the University of Washington in Seattle. Echocardiography. Echocardiographic studies were performed within 30 days before the procedure. Immediately after MBC, echocardiographic studies were per24 to 72 hours after the procedure

and repeated

6

months after the procedure. The left atria1 dimensionwas recorded from the parasternal approach by means of M-mode echocardiography. If the M-mode echocardiogram was unavailable, the left atria1 dimension was measured from two-dimensional echocardiographic images in the parasternal long-axis view posterior to the aortic root

at the level of the aortic valve. The MVA by two-dimensional echocardiography was obtained in the parasternal short-axis view. The mitral valve orifice wasplanimetered after careful scanning

1 2

(1) clinical

status, (3) results of previous diagnostic cardiac catheterization and angiography wit,hin 3 months, (4) hemody namic data immediately before and after the procedure, (5) procedural data including the equipment used, number and sizeof balloons,and duration and number of inflations, (6) Doppler echocardiographic data at baseline and

formed 4

to 10 mm)

Subvalvular thickening Minimal thickening just below the mitral leaflets Thickening of chordal structures extending up to one third of the chordal length Thickening extending to the distal third of the chordal length Extensive thickening and shortening of all chordal structures extending down to the papillary muscles Calcification A single area of increased echo brightness Scattered areas of brightness confined to leaflet margins Brightness extending into the midportion of the leaflets Extensive brightness throughout much of the leaflet tissue

the registry

Seplember 1992 Hearl Journal

from the left ventricular

apex slowly

up to the mitral valve to determine the minimal orifice area.‘s,l6 Gain settingswere at a minimal level, and the inner edgesof the echoesdefining the mitral orifice were traced. Mitral valve morphology. The causeof the mitral stenosiswasconsideredrheumatic if the leaflets showedtypical commissural fusion with doming in diastole. In these patients, mitral valve morphology was assessed and evalu-

ated for (1) leaflet mobility, (2) leaflet thickness, (3) degree of subvalvular thickening, and (4) calcification. The criteria for grading eachof thesevariablesare listed in Table I.” A scoreof 1 to 4 wasassignedto each variable. The scores from each variable were summed score was calculated.

and a total morphology

Hemodynamic and angiographic evaluation. Intracardiac pressures

were recorded

with the transducers

zeroed

in the midthoracic position. Pressuresand hemodynamic data were recorded

before the procedure

with the patient

stable and before contrast injection. After MBC all pressure recordings were repeated when the patient had returned to a stable position. The calculations of mitral valve gradient and area were based on simultaneous left atria1 or pulmonary arterial wedge and left ventricular pressure tracings. The recorded tracings were obtained in close proximity in time to the determination of cardiac output.

Cardiac output wasdetermined by direct Fick or greendye injections or by thermodilution in patients without a significant intracardiac shunt. A significant shunt was defined as one with 0.5 L/min or more left-to-right flow. The MVA from the data was calculated by means of the Gorlin formula. Mitral regurgitation was assessed by left ventricular

Volume

124

Number

3

Mitral morphology and balloon ualvuloplasty

0

Test

for

linear

trend

659

w.001

0

8 0 0

1 n=174

2 n=Z76

Valvular

Moblllty

7 l-l=93 (Grade)

A

n=12

Fig. 1. Correlation of mitral valve mobility grade by echocardiography with mitral valve area (MVA) measured by cardiac catheterization after mitral balloon commissurotomy (MBC). Box plot for each grade represents median and twenty-fifth and seventy-fifth percentiles. “Whiskers” are drawn to point within 1.5 times interquartile range.

angiography before and after MBC as mild, moderate, or severe.‘s Statistical analysis. All values are expressed as mean + SD. The echocardiographic grades for leafiet mobility, thickness, subvalvular disease, and calcification by two-dimensional echocardiography were related to the MVA obtained by cardiac catheterization immediately after MBC. The results are based on data from patients in whom both cardiac catheterization MVA after MBC and mitral valve morphology were determined. Linear regression was used to determine the significance of the relationship of continuous variables such as age and ordered categorical variables such as leaflet mobility to MVA after MBC. t Tests were used to assess the relationship between dichotomous variables such as sex and MVA. Multiple regression and stepwise multiple regression were used to determine the variables that were most related to MVA. The variables considered in these analyses were age, sex, pre-MBC MVA by cardiac catheterization, cardiac rhythm, balloon diameter, left atria1 size, pre-MBC pulmonary artery pressure, pre-MBC mitral regurgitation, pre-MBC cardiac output, and the echocardiographic morphologic variables of leaflet mobility, leaflet thickness, subvalvular thickening, calcification, and total morphology score. Jittered scatter diagrams are used to illustrate the relationship between total morphology score and MVA.l’ The jittering method adds spheric random noise to each data point, so that the plotted points are randomly scattered in a small area around the true data point to make the individual points visible. The relationships of the individual morphology characteristics to MVA are illustrated by box

plots. lg The middle line in the box represents the median; the top and bottom of the box show the twenty-fifth and seventy-fifth percentiles. The “whiskers” are drawn to the points nearest to but within 1.5 times the interquartile range. RESULTS Patient characteristics. A total of 555 patients with rheumatic mitral stenosis had baseline echocardiographic data submitted. There were 456 women (82 “0 ) and 99 men (18% ) with a mean age of 53.7 ? 14.4 years. Sinus rhythm was present in 315 (58%) patients and atria1 fibrillation in 229 (425;:). Double-balloon MBC was performed in 475 (86%) patients. Mitral valve morphology Valvular mobility. The relationship between valvular mobility and cardiac catheterization MVA immediately after MBC is shown in Fig. 1. The mean MVA for patients with grade 1 (n = 174) was 2.2 * 0.8 cm2;grade2(n = 276),1.9 & 0.7cm2;grade3(n = 93), 1.7 + 0.7 cm’; grade 4 (rz = 12), 1.9 ? 0.9 cm2. The correlation between valvular mobility and MVA was r = -0.22 (p < 0.001). Leaflet thickness. The relationship between leaflet thickness and cardiac catheterization MVA immediately after MBC is shown in Fig. 2. The mean MVA for patients with grade 1 (IZ = 96) was 2.2 & 0.7 cm2; grade 2 (n = 329), 2.0 f 0.8 cm2; grade 3 (n = 114),

660

Reid et al.

American

September 1992 Heart Journal

8

6

Test

0

/

for

lmear

trend

pc.001

0

8

0

0

O1 n=96

2

n=329 Leaflet

“56

"214 (Grade)

Thickness

Fig. 2. Correlation of mitral valve thickness gradeswith mitral valve area (MVA) measuredafter mitral balloon commissurotomy(MBC). Relationship of each gradeto MVA is shownasbox plot. Seetext for explanation of box plot.

Test

for

linear

Trend

~001

8 0

8

1

2

n=163

n=253 Subvalvular

3 n=121 Thickenmg (Grade)

4 n=lB

Fig. 3. Correlation of subvalvular thickening with cardiac catheterization mitral valve area (MVA) after mitral balloon commissurotomy (MBC) shown by box plot explained in text.

1.7 + 0.7 cm2; and grade 4 (n = 16), 1.6 -t 0.7 cm2. The correlation between leaflet thickness and MVA was r = -0.20 (p < 0.001). Subvalvular thickening. The correlation between subvalvular thickening and cardiac catheterization MVA immediately after MBC is shown in Fig. 3. The

mean MVA for patients with grade 1 (n = 163) was 2.1 + 0.8 cm2; grade 2 (n = 253), 2.0 + 0.8 cm2; grade 3 (n = 121), 1.8 +- 0.6 cm2; and grade 4 (n = 18), 1.7 ? 0.7 cm2. The correlation between subvalvular thickening and MVA was r = -0.17 (p < 0.001). Calcification. The correlation between calcifica-

Volume Number

124 3

Mitral

Test

1

for

morphology

linear

trend

and balloon valvuloplasty

661

p

Influence of mitral valve morphology on mitral balloon commissurotomy: immediate and six-month results from the NHLBI Balloon Valvuloplasty Registry.

Echocardiographic data were analyzed in 555 patients undergoing mitral balloon commissurotomy (MBC). Patients were enrolled in the National Heart, Lun...
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