Advancing Assessment of Degenerative Mitral Stenosis: The Role of Three-Dimensional Echocardiography.

Degenerative mitral stenosis (MS) related to mitral annular calcification (MAC) is increasingly observed in elderly patients and differs fundamentally from rheumatic MS. While rheumatic MS is characterized by commissural fusion and a funnel-shaped orifice at the leaflet tips, MAC produces a rigid, tubular geometry with maximal narrowing at the annular level. Conventional two-dimensional echocardiography often provides unreliable assessment of degenerative MS: anatomical evaluation is challenging because the valve has a non-planar, tubular geometry and calcification can create acoustic shadowing, and hemodynamic measurements, such as transmitral gradients, may also be misleading, as coexisting atrial or diastolic dysfunction can elevate gradients and overestimate the severity of stenosis. Three-dimensional echocardiography enables multiplanar reconstruction tailored to the underlying etiology, allowing precise planimetric measurement of the true anatomical mitral valve area. In rheumatic MS, measurements are aligned at the leaflet tips, whereas in degenerative MS, the narrowest orifice at the annular level is accurately captured. Recognizing these morphological differences ensures that three-dimensional planimetry provides an anatomically faithful and clinically meaningful assessment of MS across different etiologies.