Sex differences in left atrial volumes, mechanics and stiffness in primary mitral regurgitation- a combined 2D and 3D echocardiographic study.

BACKGROUND: Mitral regurgitation (MR) causes left atrial (LA) enlargement and impaired reservoir function. We assessed whether changes in LA size, strain and stiffness in significant (moderate or greater) primary MR are sex-specific.

METHODS AND RESULTS: In the 3D Echocardiography and Cardiovascular Prognosis in Mitral Regurgitation study (3D-PRIME), 111 patients with primary MR were prospectively investigated with 2D and 3D echocardiography. MR was severe if the 3D regurgitant fraction was ≥50%. LA size was assessed by maximum, minimum and pre-A 3D volume (LAV), mechanics by peak reservoir (LASr) and contractile strain, and stiffness by the ratio: mitral peak E-wave divided by the annular e' velocity (E/e´)/LASr.Women were older, had higher heart rate, and lower body mass index and MR regurgitant volumes (p < 0.05). 3D LAV indexed for body surface area and LA contractile strain did not differ by sex, while LASr was lower (22.2% vs. 25.0%) and LA stiffness higher in women (0.56 vs. 0.44) (p < 0.05). In linear regression analysis, female sex was associated with higher LA stiffness independent of age, minimum LAV, left ventricular global longitudinal strain, diabetes and coronary artery disease (R2 0.56, all p < 0.05). In logistic regression analysis, women had a 4.0-fold (95% CI 1.2-13.1, p = 0.02) higher adjusted risk of increased LA stiffness than men.

CONCLUSION: Women with significant primary MR have more impaired LA reservoir mechanics and increased LA stiffness compared to men despite lower MR regurgitant volumes and similar indexed LA size. The findings reveal sex-specific features of LA remodeling in MR.