Percutaneous mitral balloon valvuloplasty - state of the art
Authors: Palacios Igor F. 
Published: October 2020

Since its introduction in 1982, percutaneous mitral balloon valvuloplasty (PMV) has been used successfully as an alternative to open or closed surgical mitral commissurotomy in the treatment of patients with symptomatic rheumatic mitral stenosis. PMV is safe and effective and provides sustained clinical and hemodynamic improvement in patients with mitral stenosis. The immediate and long-term results appear to be similar to those of surgical mitral commissurotomy. Proper patient selection is an essential step for being able to predict the immediate results of PMV. Candidates for PMV require precise assessment of the mitral valve morphology. The Wilkin’s echocardiographic score (Echo-Sc) is currently the most widely used method for predicting PMV outcome. Leaflet mobility, leaflet thickening, valvular calcification, and sub valvular disease are each scored from 1 to 4. An inverse relationship exists between the Echo-Sc and PMV success. Both immediate and intermediate follow-up studies have shown that patients with Echo-Sc ≤ 8 have superior results, significantly greater survival, and event free survival compared to patients with Echo-Sc > 8. We identified other clinical and morphologic predictors of PMV success that include age, pre-PMV mitral valve area, history of previous surgical commissurotomy, and mitral regurgitation (MR), and post-PMV variables (e.g., post-PMV MR ≥ 3 + and pulmonary artery pressure), that may be used in conjunction with the Echo-Sc to optimally identify candidates for PMV. This concept demonstrates a multifactorial nature of the prediction of immediate and long-term results. Other echocardiographic scores have been developed for the screening of potential candidates for PMV. They include a unique score that take into account the length of the chordae. A novel quantitative score that included the ratio of the commissural areas over the maximal excursion of the leaflets from the annulus in diastole. The components of this score include mitral valve area ≤ 1 cm2, maximum leaflet displacement ≤ 12 mm, commissural area ratio ≥ 1.25, and sub valvular involvement. Finally, a score that is able to identify patients who are more likely to develop significant mitral regurgitation post-PMV. This score takes into account the distribution (even or uneven) of leaflet thickening and calcification, the degree and symmetry of commissural disease, and the severity of subvalvular disease. The transvenous transseptal approach is the most widely used PMV technique. The two major techniques of PMV are the double-balloon technique and the Inoue technique which are equally effective techniques of PMV. Encouraging results of PMV have been reported in special mitral stenosis population cohorts including pregnant women, patients with previous surgical commissurotomy, patients with atrial fibrillation, patients with pulmonary hypertension, elderly patients, patients with calcific mitral stenosis, and patients with associated aortic regurgitation. To summarize, PMV is the preferred form of therapy for relief of mitral stenosis for a selected group of patients with symptomatic mitral stenosis and suitable valve anatomy for valvuloplasty. Patients with Echo-Sc ≤ 8 have the best results, particularly if they are young, are in normal sinus rhythm, have no pulmonary hypertension, and have no evidence of calcification of the mitral valve under fluoroscopy. The immediate and long-term results of PMV in this group of patients are similar to those reported after surgical mitral commissurotomy. Patients with Echo-Sc > 8 have only a 50% chance to obtain a successful hemodynamic result with PMV, and the long-term follow-up results are worse than those from patients with Echo-Sc ≤ 8. In patients with Echo-Sc ≥ 12, it is unlikely that PMV could produce good immediate or long-term results and they preferably should undergo mitral valve replacement. However, PMV could be considered in these patients if they are high-risk or unqualified surgical candidates.