Severity of Subvalvular Impairment in the Results of Mitral Valvuloplasty with Inoue Catheter

Fundamentos: A valvoplastia mitral por cateter-balão foi introduzida em 1984 por Inoue e colaboradores, e atualmente é considerada o método de eleição no tratamento da estenose mitral. Objetivo: Comparar resultados de valvoplastia mitral em pacientes com estenose mitral com comprometimento subvalvar ≥3 e <3. Métodos: Estudo retrospectivo com 104 pacientes submetidos à valvoplastia mitral com balão de Inoue. Os pacientes foram estratificados em dois grupos: com comprometimento subvalvar (ASV) ≥3 e ASV <3. Realizada a comparação dos resultados imediatos, aos 12 meses e aos 24 ou mais meses entre os grupos com os dados obtidos por estudo ecocardiográfico e hemodinâmico. Resultados: Os resultados imediatos mostraram sucesso nos dois grupos, com significância estatística pré/pósprocedimento, quanto aos parâmetros ecocardiográficos e hemodinâmicos, e ausência de diferenças significativas entre os grupos. Os resultados ecocardiográficos aos 12 meses evidenciaram que o gradiente médio e a área valvar foram semelhantes e sem significância estatística entre os grupos, o mesmo acorrendo na comparação dos resultados ecocardiográficos aos 24 ou mais meses. Conclusão: Os resultados obtidos com a valvoplastia mitral com o balão de Inoue não diferiram tanto nos pacientes com comprometimento do aparelho subvalvar ≥3 quanto <3.


Introduction
Mitral balloon valvuloplasty was introduced in 1984 by Inoue et al. 1 In 1986, McKay et al. 2 put it into practice in the United States.In Brazil, it was first reported in 1987. 3t is currently considered the method of choice in the treatment of mitral stenosis. 4,5e selection of candidates for mitral valvuloplasty requires accurate assessment of the mitral valve morphology. 6The echocardiographic score proposed by Wilkins et al. 7 is currently the most widely used instrument for the assessment of morphological characteristics of the mitral valve and, along with other mitral valve structures, it can provide data on the evolution.Young patients, valve anatomy with Wilkins echocardiographic scores ≤8 points, sinus rhythm, no history of mitral regurgitation prior to the procedure or history of surgical commissurotomy are cases with better outcomes.
It is worth noting that the echocardiographic score, being a predictor of late outcome, is not a contraindication to percutaneous valvotomy, even when it is high (>8 points), especially in the subgroup of patients at high surgical risk and in pregnant women with mitral stenosis in functional class III or IV of the New York Heart Association (NYHA), on optimized medication.The immediate results were compared after dilation in both groups using echocardiographic data (mean gradient and valve area) and hemodynamic data (mean gradient and systolic blood pressure in the pulmonary artery).The results obtained by echocardiography as to the mean gradient and mitral valve area were analyzed to draw a comparison between groups at 12 months and 24 or more months post-procedure.
The finding of mitral valve area after the procedure was considered a success, as calculated by echocardiography ≥1.5 cm² or 50% gain compared to the area measured before the procedure.
Failure was defined as discontinuation of the procedure caused by technical problems or due to the development of severe mitral regurgitation (3+ or 4+) after balloon inflation or death. 11 Severe mitral regurgitation was determined by the method of Sellers et al. 10 by regurgitating contrast area within the left atrium in left ventricular systole, using 3+ and 4+ for severe degree.Using the method of echocardiography (Echo), severe mitral regurgitation was defined by the extension of regurgitant jet into the left atrium by Doppler. 12stenosis was considered when it occurred during the mitral valve area follow-up calculated by echocardiography of <1.5 cm² or loss of at least 50% of the initial gain on the first post-procedure echocardiography.
Student's t-test was used for statistical analysis, considering significance when p<0.05.

Immediate results
The procedure was successful in 103 patients (99.03%     3).

Discussion
Percutaneous mitral valvuloplasty using the Inoue technique is currently the most commonly used form of treatment of mitral stenosis in Brazil.4][15] In this study, it is observed that the patients characteristics are similar to those published by other national groups: prevalence of women (79.8%) and mean age of 33.7 years, [13][14][15] being different from those of developed countries, where patients are older and there are more men. 16,17This difference can be attributed to the rheumatic etiology of mitral stenosis in the Brazilian population and the prevalent degenerative etiology in the second group.
In the study sample, the success rate was similar to that reported by other authors: Nascimento et al.The appearance of mild mitral regurgitation after mitral valvuloplasty using balloon catheter can occur in 33% to 50% of patients. 21However, the presence of higher degrees of mitral regurgitation can be observed in the range of 4.0 to 9.0%. 6,22In the immediate results, mild mitral regurgitation is found in 18.4% of patients and moderate in 3.8% of patients, occurring similarly in both groups.In the follow-up of 24 months or more there has been a greater tendency to progression and onset of mitral regurgitation in the SVI ≥3 group.Chen et al. 19 observed 5.2% restenosis rate, Cardoso et al. 20 presented a rate of 2.3%, which is consistent with the rate found in this study (4.3%), the two cases in the SVI ≥3 group.In cases of restenosis, percutaneous mitral valvotomy can be performed as a first choice. 23There are reports of patients undergoing up to four procedures with good results. 24The two patients in this study underwent new percutaneous mitral valvuloplasty with success criteria.
The echocardiographic score proposed by Wilkins et al. 7 is a strong determinant in the indication of percutaneous mitral valvuloplasty and is well established that patients with scores ≤8 have better immediate and long-term results and lower complication rates.However, there are few studies that specifically evaluate the subvalvular structure in determining the results after mitral valvuloplasty.
Lemos et al. 25 had not found differences in the success rates considering the echocardiographic score or even when more specific characteristics are considered (e.g., abnormalities in the subvalvular structure).Abascal et al. 26 revealed that of the four components of the echocardiographic score, valvular thickening had the highest correlation with the abnormality in the valve area, followed by subvalvular disease while mobility and calcification had the lowest correlation.
Padial et al. 27 in the description of a new echocardiographic score to predict the development of severe mitral regurgitation after mitral valvuloplasty using the Inoue technique showed that the score of the subvalvular structure component of 2.6±0.5 x 1.9±0.5 was statistically significant in determining severe mitral regurgitation.
In this study, no differences were found in the immediate and medium-term results comparing the two groups of patients: with SVI ≥3 and SVI <3.

Conclusion
Percutaneous mitral valvuloplasty with Inoue balloon catheter in patients with subvalvular impairment ≥3 allows good immediate and medium-term results.It is not different from the results obtained in patients with subvalvular impairment <3.

Potential Conflicts of Interest
This study has no relevant conflicts of interest.

Sources of Funding
This study had no external funding sources.

Academic Association
This study is not associated with any graduate programs.

Table 1 Echocardiographic and hemodynamic results of the groups studied
SVI = subvalvular impairment; Echo -echocardiography

Table 2 Echocardiographic results at 12 months of the groups studied
revealed: mean gradient of 5.9±3.1 mmHg in the SVI ≥3 group and 5.3±1.6 mmHg in the SVI <3 group with no statistical significance between the groups.Valve area of 2.2±0.5 cm² in the SVI ≥3 group and 2.2±0.2cm² in the SVI <3 group with non-significant p (Table