[ Scientific Activity - Actividad Científica ] [ Brief Communications - Temas Libres ]Percutaneous Mitral Valvuloplasty: Predictors of Suboptimal Result and Mitral Regurgitation and Comparison between Double Balloon and Inoue Techniques
Wisner Jorge; Mendiz Oscar; Telayna Juan; Menendez Marcelo; Valdivieso León; Londero Hugo.
Departamento de Hemodinamia e Intervenciones
Instituto de Cardiología y Cirugía Cardiovascular.
Buenos Aires. Argentina
Material and Methods
Since its introduction by Inoue (1) et al and Lock (2) et al the
Percutaneous Mitral Valvuloplasty (PMV) has evolved into an effective method for the
treatment of patients with symptomatic mitral stenosis.
The mechanism to relieve mitral stenosis is by splitting fused commissures, which is similar to surgical commissurotomy .This has been demonstrated by pathologic specimens or intraoperative balloon dilatation(3).
A PMV is considered successful when a valve area greater than 1.5 cm 2 is achieved without major complications (Death, Emergency Surgery, Severe Mitral Regurgitation, Embolism).
The results of PMV are not uniform, a successful procedure is achieved in 80% of patients. In the remaining the valve area is minor than 1.5cm2 (Suboptimal Result) or a severe mitral regurgitation develops due to rupture of the leaflets or the subvalvular apparatus (4).
The two-dimensional and Doppler echocardiographic examination is the most important test to identify which patients should have the procedure. Wilkins (5) developed an echocardiographic score that grades the valve rigidity, valve thickening ,valve calcification and subvalvular fibrosis, with a good correlation with immediate and long term results of PMV.
Among the techniques of PMV, there are two with more extensive experience: The double balloon technique (DBT) and Inoue Technique (IT).Comparative analysis between both techniques showed similar clinical results. However the DBT is more complex to perform but allows a greater increment in the valve area.(6 7)
a) To compare baseline clinical, echocardiographic and hemodynamics characteristics of patients treated with PMV to determine predictors of Suboptimal Result (SOR) (valve area < 1.5cm2 without major complications) and Mitral Regurgitation (MR) (Severe Mitral Regurgitation or increase greater than one grade with respect to the basal situation) b) To compare clinical and hemodynamics results between the DBT and IT.
Material and Methods:
All patients had symptomatic severe mitral stenosis and were previously evaluated by
Transthoracic echocardiography (TTE)to determine the degree of valve disease, mitral
regurgitation grade and calculate the Wilkins score. On the same day of the procedure a
Transesophageal echocardiogram was performed to evaluate the presence of thrombus at
atrial appendage and the PMV was monitored by TTE.
All cases were performed by anterograde technique, IT was used in 105 patients and DBT in 29 .Selection of the technique was based on operator preference and there were no predetermined criteria.
Population:Between 1992 and 1998 134 patients were treated. The mean age was 44.8 ±13, 85.1% were female, 24.6% had atrial fibrillation and 54.1% were in functional class III - IV.
In 113 patients (84.3%) clinical success was achieved, 12 (8.9%) had SOR and 14 (10.4%) increased the MR in more than one grade (8-5.9% were severe and 6 4.4% were moderate). The incidence of major complication was 6.7% (Table I).
Suboptimal Result and Mitral Regurgitation: The analysis of the baseline characteristics of patients with SOR showed that they were more advanced in age, and had more incidence of atrial fibrillation and previous surgical commissurotomy, the Wilkins score was higher, moreover the valve area, the gradient and the stroke volume were significantly lower than patients with successful PMV (Table II Table III).
The patients which developed MR had lower incidence of cases in functional class III IV and a lower basal echocardiographic valve area. Without other characteristics that could show any difference with the successful PMV group. Multivariate Analysis with Linear Regression showed that advanced age (p < 0.0005) and Wilkins score (p < 0.02) were independent predictors of SOR. There were no predictors for MR.
Double Balloon Technique versus Inoue Technique: The analysis of the baseline clinical characteristics of both groups showed only a single significant difference, the Wilkins score was higher in the DBT group (Tables IV V).The hemodynamics results were better with DBT, obtaining a major valve area and lower final gradient.(Table VI).The clinical results were also better with DBT but the differences did not reach statistical significance probably because of the small number of patients in this group (Table VII)
Multivariate Analysis with Linear Regression showed that the basal gradient (p < 0.0005) and DBT (p< 0.03) were independent predictors of major final valve area.
Our experience coincides with the literature, as more than 80% of clinical success was
obtained. The patients which had SOR were clearly identified by its clinical and
echocardiographic characteristics. The association of small valve areas, with low
gradient, depressed stroke volume and high Wilkins score implies a more severe mitral
stenosis with a longer evolution, therefore it is not surprising that these valves were
more affected by the Rheumatic process and had worse anatomy for the PMV.
Mitral Regurgitation is one of the most severe complications of PMV and it could not be predicted with the analyzed factors. Padial (8 9 )developed a new mitral regurgitation score, it grades the commissural calcification, the leaflets thickening and calcification (and if it is even or uneven) each leaflet separately and subvalvular fibrosis as in the Wilkins score. That score demonstrated an excellent predictive value in two retrospective studies such as for DBT as for IT. Taking into account that the PMV mechanism is the commissural splitting and on the other hand that the most frequent cause of severe MR is the rupture of the leaflets, it is clear that the calcification in both commissures is of great importance in the PMV results. As the commissures could not be splitted during dilatation, the valve breaks in its most weak segments causing the leaflet or Chords rupture. This hypothesis is very attractive but it will be necessary to evaluate prospectively this new score in a greater number of patients.
The DBT allowed us to obtain better hemodynamics results in patients with worse Wilkins score, this is coincident with Fernandez-Ortiz (6)experience, he observed similar immediate results but with a significant greater incidence of bicommissural splitting with this technique, probably because a better orientation of the two balloons with respect to the fused commissures during dilatation.
Ruiz (7)compared a non randomized population, but with similar baseline characteristics, with DBT he obtained a greater increment in valve area, and also a significant major incidence of clinical success.
The patients which had SOR were clearly identified by its clinical and
echocardiographic characteristics of a more severe mitral stenosis with a longer
evolution. Wilkins score was predictive of this kind of result. There were no identifiable
predictors for MR. It will be necessary to evaluate Padial score prospectively in a
greater number of patients.
Better hemodynamics results were obtained with DBT, in patients with worse Wilkins score .Clinical results were better too, but the difference did not reach statistical significance probably because of the small number of patients in this group
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