'Frozen' posterior mitral leaflet in rheumatic mitral stenosis: Incidence and impact on outcome of balloon mitral commissurotomy

Background and aim of the study: The incidence and clinical significance of immobile and 'frozen' posterior mitral leaflet (FPML) were evaluated in the pathophysiology and immediate outcome of patients with severe pliable mitral stenosis (MS) undergoing percutaneous balloon mitral commissurotomy (PBMC). Methods: During the past four years, 30 'ideal' patients (mean age 46 ± 8 years) with Wilkins' score <8, bilateral commissural fusion and absence of commissural calcification underwent peri-procedural echocardiographic analysis. Anterior mitral leaflet (AMD mobility index (MI), chordae tendineae (CT) length, and mitral valve area (MVA) were evaluated. Results: Pre-procedure FPML was noted in 28 patients (93%). All patients achieved MVA ≤1.5 cm². Post-procedure MVA in patients with bilateral commissural splitting was 1.9 ± 0.2 cm² versus 1.6 ± 0.1 cm² in patients with unilateral commissural splitting (p <0.05). CT lengths directed to the AML and PML were 15 ± 2 mm and 8 ± 2 mm, respectively (p <0.05). MI of the AML before and immediately after PBMC was 0.4 and 0.6, respectively (p <0.05). None of the patients with FPML showed improved mobility following successful PBMC. Conclusion: FPML may be found in most patients with pliable MS. It is mainly a result of short, rigid and fused CT directed to the PML. A 'single-wing door' or a unicuspid valve may be used as a model for rheumatic pliable MS. It is suggested that pre-procedure leaflet morphology and functional assessment should focus on the AML.