ECHOCARDIOGRAPHIC RESTENOSIS AFTER SUCCESSFUL BALLOON DILATATION OF THE MITRAL-VALVE WITH THE INOUE BALLOON - EXPERIENCE OF A UNITED-KINGDOM CENTER

Objectives-(a) To assess the echocardiographic incidence of restenosis after successful balloon dilatation of the mitral valve at a mid-term follow up of one year among a population of predominantly United King dom patients. (b) To identify any factors, assessed before or during d ilatation, which may predict the development of restenosis. Design-Suc cessful dilatation of the mitral valve was defined as an increase in m itral valve area of >25% and a final valve area of at least 1-5 cm2. E chocardiographic restenosis was defined at follow up as a loss of 50% of initial gain and a valve area of less than 1.5 cm2. Mitral valve ar ea was assessed by transthoracic echocardiography before, during, 48 h ours after, and one year after successful balloon dilatation of the mi tral valve. Echo score before dilatation (an assessment of valvar and subvalvar calcification, thickening, and mobility), age, rhythm, echoc ardiographic mitral valve area before and after dilatation, left atria l pressure before and after dilatation, and end diastolic mitral valve gradient before and after dilatation were compared in those patients with and without echocardiographic restenosis at one year. Setting-A r egional cardiothoracic centre in the United Kingdom that performs 20-3 0 balloon dilatations of mitral valves each year. Patients-39 patients , with symptomatic dominant mitral stenosis, who had undergone success ful balloon dilatation of the mitral valve, and in whom echocardiograp hic assessment of mitral valve area was available at one year. 92% of patients were citizens of the United Kingdom. Interventions-Balloon di latation of the mitral valve by the Inoue technique. Main outcome meas ures-Mitral valve area and patient symptom class (New York Heart Assoc iation) one year after successful dilatation of the mitral valve. Resu lts-The incidence of echocardiographic restenosis was eight of 39 pati ents (21%). Of the eight patients with restenosis four underwent mitra l valve replacement, two had repeat dilatation of the mitral valve, an d two remained on medical treatment. With univariant analysis, factors associated with restenosis were increased age, higher echo score befo re dilatation, and a lower mitral valve area immediately after the ope ration. The only independent risk factor for restenosis, shown by mult ivariant analysis, was a high echo score before dilatation. There was no significant fall in mitral valve area at one year in those patients without restenosis. Most (28/31) of these patients had echocardiograp hic evidence of splitting of at least one commissure after dilatation compared with only two of eight patients who developed restenosis. Of 10 patients with an echo score before dilatation greater-than-or-equal -to 10 only two had an initially successful operation and no restenosi s at one year. Conclusions-The echocardiographic incidence of restenos is after dilatation of the mitral valve by the Inoue technique in pati ents of the United Kingdom is 21%. The principal factor associated wit h restenosis is a high echo score before dilatation. Increases in mitr al valve area are maintained in those patients without restenosis and it is likely that the mechanism of initial increase in valve area is d ifferent in the two groups, being commissural splitting in those patie nts who do not get restenosis and valve stretching in those that do. I n patients with an echo score greater-than-or-equal-to 10 dilatation o f the mitral valve should be considered only as a palliative procedure .