Mitral annular remodeling with varying degrees and mechanisms of chronic mitral regurgitation

Degree of mitral annular remodeling is directly associated with severity of chronic mitral regurgitation (MR). Mitral annular remodeling occurs in a symmetric fashion, regardless of MR severity. In addition to MR severity, MR mechanism plays a significant role in mitral annular remodeling.

Limited data exists on mitral annular remodeling in patients with MR. Identification of annular changes may be important in aiding surgical repair.

Mitral annular dimensions (anteroposterior, intercommissural, surface area, and circumference) were measured in end systole and diastole using 3-dimensional reconstructive software in 83 patients: trace to no MR (23), mild MR (15), moderate MR (26), and severe MR (19). Annular sphericity indices were determined by dividing intercommissural by anteroposterior dimensions. Patients were further subgrouped by mechanism of MR.

With increasing MR severity, there was a corresponding increase in all annular measurements, most pronounced in the anteroposterior dimension, circumference, and area. Larger increases were seen in patients with prolapse/flail and dilated mechanisms. Furthermore, the mitral annulus became more circular (sphericity index approached 1.0) with increasing MR severity. Patients with prolapse/flail mechanisms exhibited normal left ventricular volumes despite significant annular enlargement.

Mitral annular remodeling is directly associated with MR severity and occurs in an asymmetric fashion, yet is not limited to one region of the annulus. Mechanism of MR plays a significant role in annular remodeling. Annular remodeling can occur independently of left ventricular remodeling.