Rheumatic and Degenerative Native Mitral Stenosis: Two Distinct Diseases with Different Diagnostic and Therapeutic Implications

Mitral stenosis is a progressive valvular disease characterized by obstruction of left ventricular inflow and impaired diastolic filling. Rheumatic mitral stenosis (RMS) and degenerative mitral stenosis (DMS) are distinct entities with different etiologist, pathophysiology, and clinical courses. RMS results from autoimmune-mediated valvulitis following group A streptococcal infection, leading to leaflet thickening, commissural fusion, chordal shortening, and a funnel-shaped valve orifice. In contrast, DMS is caused by mitral annular calcification, producing circumferential annular and basal leaflet narrowing, usually with preserved leaflet tips, and frequently coexisting with other degenerative valvular diseases. These anatomical differences translate into distinct hemodynamic mechanisms: RMS primarily increases resistance at the leaflet tips, whereas DMS raises left atrial pressures through annular rigidity and reduced atrioventricular compliance. Echocardiography remains the cornerstone of diagnosis, while three-dimensional imaging and cardiac computed tomography play a key role in procedural planning. RMS often responds favourably to percutaneous balloon mitral valvuloplasty, whereas DMS more commonly requires surgical or transcatheter mitral valve replacement, particularly in high-risk patients. Accurate differentiation between RMS and DMS is essential for appropriate patient selection, risk stratification, and optimal outcomes. This review highlights the main differences between RMS and DMS, with particular emphasis on the role of pre-procedural multimodality imaging in guiding treatment strategies.